RECORD OF BUILDING EVACUATION
Occupational Health and Safety is required to maintain records of all emergency evacuations from University premises and buildings, regardless of cause. This information is reported to the Occupational Health and Safety Policy Committee, and in the event of any incident, can be used to show the level of training and experience building occupants have had with respect to emergency procedures and evacuations.
To this end, it is important that this form be completed as soon as possible after every evacuation, regardless of cause, and forwarded to Occupational Health and Safety. All sections of this form must be completed.
Campus
Building Name Building No.
Compiled by: Position:
a. Evacuation Time / Date:
Day: Date: Time:
b. Cause:
Genuine Emergency: 0 Provide details in “d” below. Include how alarm was activated
False Alarm: 0 Provide details in “d” below. Include how alarm was activated
Drill 0
c. Evacuation Details:
Were any parts of the building not evacuated? Yes 0 No 0
Were any mobility-impaired people present? Yes 0 No 0
Did anyone remain in the building after the evacuation? Yes 0 No 0
Did anyone refuse to leave the building during the evacuation? Yes 0 No 0
Did the alarm system malfunction in any way? Yes 0 No 0
Were any other faults or deficiencies noted? Yes 0 No 0
(e.g. procedures inadequate, response time too long, announcements
inaudible etc)
Were there any obstructions, stored materials, equipment in exit Yes 0 No 0
corridors, exit doors or stairs?
d. Additional information, including details relating to all questions marked “yes” in “c” above, and the cause of the evacuation from “b”. Include floor numbers/room numbers where appropriate and any corrective action needed or taken.
.................................................................................................................................................................................................
.................................................................................................................................................................................................
.................................................................................................................................................................................................
.................................................................................................................................................................................................
Please send completed questionnaire to:
Register of Building Evacuations
Occupational Health and Safety
Clayton Campus
and Zone Faculty OHS&E Committee
for your department.
Thursday, 28 May 2009
10.standard procedure in an electrical driven machine
Laboratory supply of mains electricity is via individual socket outlets that may be 3-phase 415 V, 50 Hz, or single-phase 240 V, 50 Hz. Office supplies are normally 240 V, 50 Hz. Most electrical equipment operates on 240 V, 50 Hz.A wide range of electrically powered equipment is found in the laboratory including fluid and vacuum pumps, lasers, power supplies, electrophoresis and electrochemical apparatus, X-ray equipment, stirrers, hot plates, ovens both conventional and microwave and computers, printers and VDU equipment. In the office, there are, amongst other things, computer equipment, FAX machines and photocopiers. In the lecture theatres there are overhead and slide projectors. In fact, everyone in the School of Chemistry is exposed at some time to electrical equipment.
Hazards
· Electric shock is the effect produced on the body and particularly on the nervous system by an electrical current passing through it. The effect depends on the current strength which itself depends on the voltage and body resistance i.e. path length and surface resistance of skin (which is much reduced when wet). Death can be the result of the normal voltage of 240 V causing currents of greater than 30 mA to flow through the body for more than 40 ms. Minor shocks may also cause injury following involuntary muscle contraction.
· Burns caused by the passage of heavy currents through the body or by direct contact with an electrically heated surface.
· Explosion and fire caused by electrical sparks, short circuits or overload heating, old wiring in the presence of flammable material. Injury from microwave and radio-frequency sources and from induction heating equipment.
Control Measures
These precautions are not meant to be exhaustive or to cover aspects of repair or construction of electrical equipment (details of such can be found in the University Code of Practice "Electrical Safety") but to cover everyday use in the laboratory and office.
Plugs and fuses
· Plugs that are cracked or broken must not be used. The plugs must be wired properly, the conductors securely fixed and the cable firmly held by the strain relief grip.
· The rating of the fuse must be appropriate to the appliance. Most electronic equipment (computers, measuring instruments etc.) requires only a 3 A fuse which will load to 720 W. Reserve 13 A fuses (loading to 3000 W) for heavier equipment. Electronic Workshop personnel will advise in case of doubt.
Cabling
· The cable must be in good condition and free from breaks in the insulation. Cable must be sufficiently robust to withstand the wear and tear of laboratory or office use and fully waterproof where water may come within the vicinity of the apparatus.
· Cables must not be run across the floor in such a way as to cause a tripping hazard or to be susceptible to damage from passing traffic. If it is necessary to run cables across walkways, they must be covered with cable protectors.
Extensions /Adaptors
It is permissible if necessary to feed one four way extension block from a single socket provided the block feeds only low power equipment (less than 500 W or 2 A). Extension leads must not be daisy-chained. Kettles, microwaves and heaters that have higher power demands must not be used on such an extension but must be fed from an installed socket point.
240V multi-way adaptors are forbidden by the University
Mains Switch
The location of any mains switch must be clear and known so that power can be turned off rapidly in an emergency.
Use
· No apparatus with exposed mains terminals should ever be used.
· Ordinary electrical equipment must not be used in the vicinity of flammable or explosive gases. Ordinary electrical equipment is a possible source of ignition.
· Ordinary electrical equipment must not be used where it may get wet. Water may cause a dangerous short circuit.
· Equipment that has been wet must never be switched on until the equipment has been tested. Anyone to whom the equipment is taken for testing must be informed about what has happened.
Repairs
· Electrical equipment must not be "repaired" except by a competent person.
· Equipment must be disconnected from the main power before beginning.
· If there is any doubt, equipment should be taken to the Electronics Workshop for repair.
Testing
It is required by law that electrical equipment is tested from time to time. The School of Chemistry policy on this matter is described here. Most portable items of equipment i.e. those that can be unplugged from the wall, carry a School of Biological and Chemical Sciences identification label and a most recent testing date. Apparatus with a FAILED sticker must never be used. Before embarking on more sophisticated electrical work such as building custom equipment, the University Code of Practice entitled "Electrical Safety" should be consulted with particular attention paid to the regulations covering the proper insulation of conductors and
Hazards
· Electric shock is the effect produced on the body and particularly on the nervous system by an electrical current passing through it. The effect depends on the current strength which itself depends on the voltage and body resistance i.e. path length and surface resistance of skin (which is much reduced when wet). Death can be the result of the normal voltage of 240 V causing currents of greater than 30 mA to flow through the body for more than 40 ms. Minor shocks may also cause injury following involuntary muscle contraction.
· Burns caused by the passage of heavy currents through the body or by direct contact with an electrically heated surface.
· Explosion and fire caused by electrical sparks, short circuits or overload heating, old wiring in the presence of flammable material. Injury from microwave and radio-frequency sources and from induction heating equipment.
Control Measures
These precautions are not meant to be exhaustive or to cover aspects of repair or construction of electrical equipment (details of such can be found in the University Code of Practice "Electrical Safety") but to cover everyday use in the laboratory and office.
Plugs and fuses
· Plugs that are cracked or broken must not be used. The plugs must be wired properly, the conductors securely fixed and the cable firmly held by the strain relief grip.
· The rating of the fuse must be appropriate to the appliance. Most electronic equipment (computers, measuring instruments etc.) requires only a 3 A fuse which will load to 720 W. Reserve 13 A fuses (loading to 3000 W) for heavier equipment. Electronic Workshop personnel will advise in case of doubt.
Cabling
· The cable must be in good condition and free from breaks in the insulation. Cable must be sufficiently robust to withstand the wear and tear of laboratory or office use and fully waterproof where water may come within the vicinity of the apparatus.
· Cables must not be run across the floor in such a way as to cause a tripping hazard or to be susceptible to damage from passing traffic. If it is necessary to run cables across walkways, they must be covered with cable protectors.
Extensions /Adaptors
It is permissible if necessary to feed one four way extension block from a single socket provided the block feeds only low power equipment (less than 500 W or 2 A). Extension leads must not be daisy-chained. Kettles, microwaves and heaters that have higher power demands must not be used on such an extension but must be fed from an installed socket point.
240V multi-way adaptors are forbidden by the University
Mains Switch
The location of any mains switch must be clear and known so that power can be turned off rapidly in an emergency.
Use
· No apparatus with exposed mains terminals should ever be used.
· Ordinary electrical equipment must not be used in the vicinity of flammable or explosive gases. Ordinary electrical equipment is a possible source of ignition.
· Ordinary electrical equipment must not be used where it may get wet. Water may cause a dangerous short circuit.
· Equipment that has been wet must never be switched on until the equipment has been tested. Anyone to whom the equipment is taken for testing must be informed about what has happened.
Repairs
· Electrical equipment must not be "repaired" except by a competent person.
· Equipment must be disconnected from the main power before beginning.
· If there is any doubt, equipment should be taken to the Electronics Workshop for repair.
Testing
It is required by law that electrical equipment is tested from time to time. The School of Chemistry policy on this matter is described here. Most portable items of equipment i.e. those that can be unplugged from the wall, carry a School of Biological and Chemical Sciences identification label and a most recent testing date. Apparatus with a FAILED sticker must never be used. Before embarking on more sophisticated electrical work such as building custom equipment, the University Code of Practice entitled "Electrical Safety" should be consulted with particular attention paid to the regulations covering the proper insulation of conductors and
8.what is Ergonomic?
Ergonomic research is performed by those who study human capabilities in relationship to their work demands. Information derived from these studies contributes to the design and evaluation of tasks, jobs, products, environments and systems in order to make them compatible with the needs, abilities and limitations of people.
Five aspects of ergonomics
There are five aspects of ergonomics: safety, comfort, ease of use, productivity/performance, and aesthetics. Based on these aspects of ergonomics, examples are given of how products or systems could benefit from redesign based on ergonomic principles.
Safety - Medicine bottles: The print on them could be larger so that a sick person who may have bad vision (due to sinuses, etc.) can more easily see the dosages and label. Ergonomics could design the print style, color and size for optimal viewing.
Comfort - Alarm clock display: Some displays are harshly bright, drawing one’s eye to the light when surroundings are dark. Ergonomic principles could re-design this based on contrast principles.
Ease of use - Street Signs: In a strange area, many times it is difficult to spot street signs. This could be addressed with the principles of visual detection in ergonomics.
Productivity/performance - HD TV: The sound on HD TV is much lower than regular TV. So when you switch from HD to regular, the volume increases dramatically. Ergonomics recognizes that this difference in decibel level creates a difference in loudness and hurts human ears and this could be solved by evening out the decibel levels.
Aesthetics - the look and feel of the object, the user experience.
[edit] Domains
The International Ergonomics Association (IEA) divides ergonomics broadly into three domains:
Physical ergonomics: is concerned with human anatomical, anthropometric, physiological and biomechanical characteristics as they relate to physical activity. (Relevant topics include working postures, materials handling, repetitive movements, work related musculoskeletal disorders, workplace layout, safety and health.)
Cognitive ergonomics: is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system design.)
Organizational ergonomics: is concerned with the optimization of sociotechnical systems, including their organizational structures, policies, and processes.(Relevant topics include communication, crew resource management, work design, design of working times, teamwork, participatory design, community ergonomics, cooperative work, new work paradigms, virtual organizations, telework, and quality management.)
[edit] History
The foundations of the science of ergonomics appear to have been laid within the context of the culture of Ancient Greece. A good deal of evidence indicates that Hellenic civilization in the 5th century BCE used ergonomic principles in the design of their tools, jobs, and workplaces. One outstanding example of this can be found in the description Hippocrates gave of how a surgeon's workplace should be designed (see Marmaras, Poulakakis and Papakostopoulos, 1999) [4].
The term ergonomics is derived from the Greek words ergon [work] and nomos [natural laws] and first entered the modern lexicon when Wojciech Jastrzębowski used the word in his 1857 article Rys ergonomji czyli nauki o pracy, opartej na prawdach poczerpniętych z Nauki Przyrody (The Outline of Ergonomics, i.e. Science of Work, Based on the Truths Taken from the Natural Science).
Later, in the 19th century, Frederick Winslow Taylor pioneered the "Scientific Management" method, which proposed a way to find the optimum method for carrying out a given task. Taylor found that he could, for example, triple the amount of coal that workers were shoveling by incrementally reducing the size and weight of coal shovels until the fastest shoveling rate was reached. Frank and Lillian Gilbreth expanded Taylor's methods in the early 1900s to develop "Time and Motion Studies". They aimed to improve efficiency by eliminating unnecessary steps and actions. By applying this approach, the Gilbreths reduced the number of motions in bricklaying from 18 to 4.5, allowing bricklayers to increase their productivity from 120 to 350 bricks per hour.
World War II marked the development of new and complex machines and weaponry, and these made new demands on operators' cognition. The decision-making, attention, situational awareness and hand-eye coordination of the machine's operator became key in the success or failure of a task. It was observed that fully functional aircraft, flown by the best-trained pilots, still crashed. In 1943, Alphonse Chapanis, a lieutenant in the U.S. Army, showed that this so-called "pilot error" could be greatly reduced when more logical and differentiable controls replaced confusing designs in airplane cockpits.
In the decades since the war, ergonomics has continued to flourish and diversify. The Space Age created new human factors issues such as weightlessness and extreme g-forces. How far could environments in space be tolerated, and what effects would they have on the mind and body? The dawn of the Information Age has resulted in the new ergonomics field of human-computer interaction (HCI). Likewise, the growing demand for and competition among consumer goods and electronics has resulted in more companies including human factors in product design.
At home, work, or play new problems and questions must be resolved constantly. People come in all different shapes and sizes, and with different capabilities and limitations in strength, speed, judgment, and skills. All of these factors need to be considered in the design function. To solve design problems, physiology and psychology must be included with a engineering approach
Fields of ergonomics
[edit] Engineering psychology
Engineering psychology is an interdisciplinary part of Ergonomics and studies the relationships of people to machines, with the intent of improving such relationships. This may involve redesigning equipment, changing the way people use machines, or changing the location in which the work takes place. Often, the work of an engineering psychologist is described as making the relationship more "user-friendly."
Engineering Psychology is an applied field of psychology concerned with psychological factors in the design and use of equipment. Human factors is broader than engineering psychology, which is focused specifically on designing systems that accommodate the information-processing capabilities of the brain.[8]
[edit] Macroergonomics
Macroergonomics is an approach to ergonomics that emphasizes a broad system view of design, examining organizational environments, culture, history, and work goals. It deals with the physical design of tools and the environment. It is the study of the society/technology interface and their consequences for relationships, processes, and institutions. It also deals with the optimization of the designs of organizational and work systems through the consideration of personnel, technological, and environmental variables and their interactions. The goal of macroergonomics is a completely efficient work system at both the macro- and micro-ergonomic level which results in improved productivity, and employee satisfaction, health, safety, and commitment. It analyzes the whole system, finds how each element should be placed in the system, and considers all aspects for a fully efficient system. A misplaced element in the system can lead to total failure.
History
Macroergonomics, also known as organizational design and management factors, deals with the overall design of work systems. This domain did not begin to receive recognition as a sub-discipline of ergonomics until the beginning of the 1980s. The idea and current perspective of the discipline was the work of the U.S. Human Factors Society Select Committee on the Future of Human Factors, 1980-2000. This committee was formed to analyze trends in all aspects of life and to look at how they would impact ergonomics over the following 20 years. The developments they found include:
Breakthroughs in technology that would change the nature of work, such as the desktop computer,
The need for organizations to adapt to the expectations and needs of this more mature workforce,
Differences between the post-World War II generation and the older generation regarding their expectations the nature of the new workplace,
The inability of solely microergonomics to achieve reductions in lost-time accidents and injuries and increases in productivity,
Increasing workplace liability litigation based on safety design deficiencies.
These predictions have become and continue to become reality. The macroergonomic intervention in the workplace has been particularly effective in establishing a work culture that promotes and sustains performance and safety improvements.
Methods[9]
Cognitive Walk-through Method: This method is a usability inspection method in which the evaluators can apply user perspective to task scenarios to identify design problems. As applied to macroergonomics, evaluators are able to analyze the usability of work system designs to identify how well a work system is organized and how well the workflow is integrated.
Kansei Method: This is a method that transforms consumer’s responses to new products into design specifications. As applied to macroergonomics, this method can translate employee’s responses to changes to a work system into design specifications.
High Integration of Technology, Organization, and People (HITOP): This is a manual procedure done step-by-step to apply technological change to the workplace. It allows managers to be more aware of the human and organizational aspects of their technology plans, allowing them to efficiently integrate technology in these contexts.
Top Modeler: This model helps manufacturing companies identify the organizational changes needed when new technologies are being considered for their process.
Computer-integrated Manufacturing, Organization, and People System Design (CIMOP): This model allows for evaluating computer-integrated manufacturing, organization, and people system design based on knowledge of the system.
Anthropotechnology: This method considers analysis and design modification of systems for the efficient transfer of technology from one culture to another.
Systems Analysis Tool (SAT): This is a method to conduct systematic trade-off evaluations of work-system intervention alternatives.
Macroergonomic Analysis of Structure (MAS): This method analyzes the structure of work systems according to their compatibility with unique sociotechnical aspects.
Macroergonomic Analysis and Design (MEAD): This method assesses work-system processes by using a ten-step process.
[edit] Seating Ergonomics
The best way to reduce pressure in the back is to be in a standing position. However, there are times when you need to sit. When sitting, the main part of the body weight is transferred to the seat. Some weight is also transferred to the floor, back rest, and armrests. Where the weight is transferred is the key to a good seat design. When the proper areas are not supported, sitting in a seat all day can put unwanted pressure on the back causing pain.
The lumbar (bottom five vertebrate in the spine) needs to be supported to decrease disc pressure. Providing both a seat back that inclines backwards and has a lumbar support is critical to prevent excessive low back pressures. The combination which minimizes pressure on the lower back is having a backrest inclination of 120 degrees and a lumbar support of 5 cm. The 120 degrees inclination means the angle between the seat and the backrest should be 120 degrees. The lumbar support of 5 cm means the chair backrest supports the lumbar by sticking out 5 cm in the lower back area.
Another key to reducing lumbar disc pressure is the use of armrests. They help by putting the force of your body not entirely on the seat and back rest, but putting some of this pressure on the armrests. Armrest needs to be adjustable in height to assure shoulders are not overstressed.
[edit] Organizations
The International Ergonomics Association [1] (IEA) is a federation of ergonomics and human factors societies from around the world. The mission of the IEA is to elaborate and advance ergonomics science and practice, and to improve the quality of life by expanding its scope of application and contribution to society. As of September 2008, the International Ergonomics Association has 46 federated societies and 2 affiliated societies.
The International Society of Automotive Engineers (SAE) is a professional organization for mobility engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others. The Society of Automotive Engineers has established a number of standards used in the automotive industry and elsewhere. It encourages the design of vehicles in accordance with established Human Factors principles. It is one the most influential organizations with respect to Ergonomics work in Automotive Design. This society regularly holds conferences which address topics spanning all aspects of Human Factors/Ergonomics.
reference
http://en.wikipedia.org/wiki/Ergonomics
Five aspects of ergonomics
There are five aspects of ergonomics: safety, comfort, ease of use, productivity/performance, and aesthetics. Based on these aspects of ergonomics, examples are given of how products or systems could benefit from redesign based on ergonomic principles.
Safety - Medicine bottles: The print on them could be larger so that a sick person who may have bad vision (due to sinuses, etc.) can more easily see the dosages and label. Ergonomics could design the print style, color and size for optimal viewing.
Comfort - Alarm clock display: Some displays are harshly bright, drawing one’s eye to the light when surroundings are dark. Ergonomic principles could re-design this based on contrast principles.
Ease of use - Street Signs: In a strange area, many times it is difficult to spot street signs. This could be addressed with the principles of visual detection in ergonomics.
Productivity/performance - HD TV: The sound on HD TV is much lower than regular TV. So when you switch from HD to regular, the volume increases dramatically. Ergonomics recognizes that this difference in decibel level creates a difference in loudness and hurts human ears and this could be solved by evening out the decibel levels.
Aesthetics - the look and feel of the object, the user experience.
[edit] Domains
The International Ergonomics Association (IEA) divides ergonomics broadly into three domains:
Physical ergonomics: is concerned with human anatomical, anthropometric, physiological and biomechanical characteristics as they relate to physical activity. (Relevant topics include working postures, materials handling, repetitive movements, work related musculoskeletal disorders, workplace layout, safety and health.)
Cognitive ergonomics: is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system design.)
Organizational ergonomics: is concerned with the optimization of sociotechnical systems, including their organizational structures, policies, and processes.(Relevant topics include communication, crew resource management, work design, design of working times, teamwork, participatory design, community ergonomics, cooperative work, new work paradigms, virtual organizations, telework, and quality management.)
[edit] History
The foundations of the science of ergonomics appear to have been laid within the context of the culture of Ancient Greece. A good deal of evidence indicates that Hellenic civilization in the 5th century BCE used ergonomic principles in the design of their tools, jobs, and workplaces. One outstanding example of this can be found in the description Hippocrates gave of how a surgeon's workplace should be designed (see Marmaras, Poulakakis and Papakostopoulos, 1999) [4].
The term ergonomics is derived from the Greek words ergon [work] and nomos [natural laws] and first entered the modern lexicon when Wojciech Jastrzębowski used the word in his 1857 article Rys ergonomji czyli nauki o pracy, opartej na prawdach poczerpniętych z Nauki Przyrody (The Outline of Ergonomics, i.e. Science of Work, Based on the Truths Taken from the Natural Science).
Later, in the 19th century, Frederick Winslow Taylor pioneered the "Scientific Management" method, which proposed a way to find the optimum method for carrying out a given task. Taylor found that he could, for example, triple the amount of coal that workers were shoveling by incrementally reducing the size and weight of coal shovels until the fastest shoveling rate was reached. Frank and Lillian Gilbreth expanded Taylor's methods in the early 1900s to develop "Time and Motion Studies". They aimed to improve efficiency by eliminating unnecessary steps and actions. By applying this approach, the Gilbreths reduced the number of motions in bricklaying from 18 to 4.5, allowing bricklayers to increase their productivity from 120 to 350 bricks per hour.
World War II marked the development of new and complex machines and weaponry, and these made new demands on operators' cognition. The decision-making, attention, situational awareness and hand-eye coordination of the machine's operator became key in the success or failure of a task. It was observed that fully functional aircraft, flown by the best-trained pilots, still crashed. In 1943, Alphonse Chapanis, a lieutenant in the U.S. Army, showed that this so-called "pilot error" could be greatly reduced when more logical and differentiable controls replaced confusing designs in airplane cockpits.
In the decades since the war, ergonomics has continued to flourish and diversify. The Space Age created new human factors issues such as weightlessness and extreme g-forces. How far could environments in space be tolerated, and what effects would they have on the mind and body? The dawn of the Information Age has resulted in the new ergonomics field of human-computer interaction (HCI). Likewise, the growing demand for and competition among consumer goods and electronics has resulted in more companies including human factors in product design.
At home, work, or play new problems and questions must be resolved constantly. People come in all different shapes and sizes, and with different capabilities and limitations in strength, speed, judgment, and skills. All of these factors need to be considered in the design function. To solve design problems, physiology and psychology must be included with a engineering approach
Fields of ergonomics
[edit] Engineering psychology
Engineering psychology is an interdisciplinary part of Ergonomics and studies the relationships of people to machines, with the intent of improving such relationships. This may involve redesigning equipment, changing the way people use machines, or changing the location in which the work takes place. Often, the work of an engineering psychologist is described as making the relationship more "user-friendly."
Engineering Psychology is an applied field of psychology concerned with psychological factors in the design and use of equipment. Human factors is broader than engineering psychology, which is focused specifically on designing systems that accommodate the information-processing capabilities of the brain.[8]
[edit] Macroergonomics
Macroergonomics is an approach to ergonomics that emphasizes a broad system view of design, examining organizational environments, culture, history, and work goals. It deals with the physical design of tools and the environment. It is the study of the society/technology interface and their consequences for relationships, processes, and institutions. It also deals with the optimization of the designs of organizational and work systems through the consideration of personnel, technological, and environmental variables and their interactions. The goal of macroergonomics is a completely efficient work system at both the macro- and micro-ergonomic level which results in improved productivity, and employee satisfaction, health, safety, and commitment. It analyzes the whole system, finds how each element should be placed in the system, and considers all aspects for a fully efficient system. A misplaced element in the system can lead to total failure.
History
Macroergonomics, also known as organizational design and management factors, deals with the overall design of work systems. This domain did not begin to receive recognition as a sub-discipline of ergonomics until the beginning of the 1980s. The idea and current perspective of the discipline was the work of the U.S. Human Factors Society Select Committee on the Future of Human Factors, 1980-2000. This committee was formed to analyze trends in all aspects of life and to look at how they would impact ergonomics over the following 20 years. The developments they found include:
Breakthroughs in technology that would change the nature of work, such as the desktop computer,
The need for organizations to adapt to the expectations and needs of this more mature workforce,
Differences between the post-World War II generation and the older generation regarding their expectations the nature of the new workplace,
The inability of solely microergonomics to achieve reductions in lost-time accidents and injuries and increases in productivity,
Increasing workplace liability litigation based on safety design deficiencies.
These predictions have become and continue to become reality. The macroergonomic intervention in the workplace has been particularly effective in establishing a work culture that promotes and sustains performance and safety improvements.
Methods[9]
Cognitive Walk-through Method: This method is a usability inspection method in which the evaluators can apply user perspective to task scenarios to identify design problems. As applied to macroergonomics, evaluators are able to analyze the usability of work system designs to identify how well a work system is organized and how well the workflow is integrated.
Kansei Method: This is a method that transforms consumer’s responses to new products into design specifications. As applied to macroergonomics, this method can translate employee’s responses to changes to a work system into design specifications.
High Integration of Technology, Organization, and People (HITOP): This is a manual procedure done step-by-step to apply technological change to the workplace. It allows managers to be more aware of the human and organizational aspects of their technology plans, allowing them to efficiently integrate technology in these contexts.
Top Modeler: This model helps manufacturing companies identify the organizational changes needed when new technologies are being considered for their process.
Computer-integrated Manufacturing, Organization, and People System Design (CIMOP): This model allows for evaluating computer-integrated manufacturing, organization, and people system design based on knowledge of the system.
Anthropotechnology: This method considers analysis and design modification of systems for the efficient transfer of technology from one culture to another.
Systems Analysis Tool (SAT): This is a method to conduct systematic trade-off evaluations of work-system intervention alternatives.
Macroergonomic Analysis of Structure (MAS): This method analyzes the structure of work systems according to their compatibility with unique sociotechnical aspects.
Macroergonomic Analysis and Design (MEAD): This method assesses work-system processes by using a ten-step process.
[edit] Seating Ergonomics
The best way to reduce pressure in the back is to be in a standing position. However, there are times when you need to sit. When sitting, the main part of the body weight is transferred to the seat. Some weight is also transferred to the floor, back rest, and armrests. Where the weight is transferred is the key to a good seat design. When the proper areas are not supported, sitting in a seat all day can put unwanted pressure on the back causing pain.
The lumbar (bottom five vertebrate in the spine) needs to be supported to decrease disc pressure. Providing both a seat back that inclines backwards and has a lumbar support is critical to prevent excessive low back pressures. The combination which minimizes pressure on the lower back is having a backrest inclination of 120 degrees and a lumbar support of 5 cm. The 120 degrees inclination means the angle between the seat and the backrest should be 120 degrees. The lumbar support of 5 cm means the chair backrest supports the lumbar by sticking out 5 cm in the lower back area.
Another key to reducing lumbar disc pressure is the use of armrests. They help by putting the force of your body not entirely on the seat and back rest, but putting some of this pressure on the armrests. Armrest needs to be adjustable in height to assure shoulders are not overstressed.
[edit] Organizations
The International Ergonomics Association [1] (IEA) is a federation of ergonomics and human factors societies from around the world. The mission of the IEA is to elaborate and advance ergonomics science and practice, and to improve the quality of life by expanding its scope of application and contribution to society. As of September 2008, the International Ergonomics Association has 46 federated societies and 2 affiliated societies.
The International Society of Automotive Engineers (SAE) is a professional organization for mobility engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others. The Society of Automotive Engineers has established a number of standards used in the automotive industry and elsewhere. It encourages the design of vehicles in accordance with established Human Factors principles. It is one the most influential organizations with respect to Ergonomics work in Automotive Design. This society regularly holds conferences which address topics spanning all aspects of Human Factors/Ergonomics.
reference
http://en.wikipedia.org/wiki/Ergonomics
7.standard machine operating procedure
Procedures and Specific Requirements
Accident risks can be reduced with adequate machine safeguarding. Identifying obvious and hidden hazards should be the first step in planning and reviewing the need for machine tool safeguarding. The information presented in this chapter should be considered as a starting point.
Most incidents leading to injury are the result of inadvertent or unwise contact with moving machine parts. Because of the great diversity of machine designs and functions, appropriate safeguarding to protect workers from such hazards may also have numerous forms. Certain principles, however, are basic to any effective safeguarding design.
Machine Safeguarding Evaluation and Design
A uniform process should be applied and used to evaluate each of the hazards on the machine to develop the required level of safeguarding. The evaluation can be performed by a knowledgeable and experienced person internal to SLAC, or for more complicated machine designs and safeguarding issues, the evaluation can be conducted by a qualified third party.
The OSHA/ANSI hierarchy for controlling machine hazards is as follows:
Eliminate the hazard by design
Control the hazard by guarding or devices
Warnings
Personal protective equipment
Training
If the results of the hazard evaluation show the equipment to be safe (that is, poses no hazard to the employee), changes to the equipment may not be necessary. This may be true for manually-powered equipment.
See Tools, Machine Safeguarding Design Considerations, for further explanations and information.
General Safeguarding Methods and Options
See Tools, Machine Safeguarding General Methods and Options, for general ideas and approved types of guards and devices.
Equipment-specific Techniques
See Tools, Machine Safeguarding Equipment-specific Techniques, for information on the recommended techniques for the guarding of specific types of machines.
Equipment Maintenance
Machine custodians will establish and follow a program of periodic and regular inspections and maintenance of their equipment to ensure that machines, parts, and auxiliary equipment are in a safe operating condition and necessary safeguards are present. Records of these inspections should be maintained and made available for inspection upon request.
Only authorized personnel will be permitted to maintain or repair machine tools. When service occurs that requires entry of any body part into a danger zone within the equipment, or unexpected startup or energizing of the machine could cause injury, maintenance personnel will first isolate hazardous energies as required by the SLAC Lock and Tag Program for the Control of Hazardous Energy.
Other Requirements
Positive Disconnecting Means
To enable proper isolation of hazardous energies before and during equipment maintenance and repair, machines and equipment operated by electric motors or other hazardous energy will be provided with a positive disconnecting means. Examples of positive disconnecting means include quick disconnect knife switches, circuit breakers, valves, and power cords and plugs. Push buttons, selector switches, software interlocks, control circuit type devices, and computer controlled software cannot be used to isolate hazardous energy.
Stop Buttons and Power Controls
Machines should have an emergency power off (EPO) or stop button or other readily-accessible and clearly designated power switch within easy reach of the operator to cut off the power to each machine. The power controls must be located so as to make it unnecessary to reach over or near the hazard to make adjustments. For larger machines, power switches should be located in multiple locations on various sides so that power can be easily deactivated by bystanders in case of emergency.
Machine Anchoring
Machines designed for a fixed location will be securely anchored to prevent walking or moving due to vibration, rotation, or seismic activity.
Manual Reset
Proper restart systems must be installed on all powered equipment and tools so that manual reset is required to restart the tool after it has been stopped by any safety device or mechanism. For example, if an interlocked guard stops tool operation when the guard is removed, manual reset is required to restart the tool after the guard is replaced. Replacing the guard alone must not allow the tool to restart. Manual reset is typically achieved by requiring the tool operator to press a reset button in order to restart the tool.
Anti-Restart Devices
Anti-restart devices (ARDs) or other effective provisions must be present on all woodworking machines and mechanical power presses which could create hazardous conditions to employees if motors were to suddenly restart after a restoration of voltage conditions following a power failure. It is strongly recommended that any machine that could pose a hazard to employees upon restoration of power also be provided with an ARD. Although there is no explicit regulatory requirement for metal working or other machines to have ARDs, the machines should at a minimum be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL) and conform to the applicable standard in the American National Standards Institute B11 series (see Resources)
In addition, the machine should be evaluated (see above Section, “Machine Safeguarding Evaluation and Design”) to determine the risk to employees if an ARD is not present. A sudden restoration of power following an interruption should not create hazardous conditions to employees. (See Tools, Machine Safeguarding Anti-restart Devices, for more information and detailed requirements.)
Malfunctioning Machinery or Safeguards
Malfunctioning machinery or safeguards must be reported immediately to the area supervisor or machine custodian. If the malfunction presents a safety hazard, the machine must be taken out of service by disconnecting and locking out the power source(s). A warning sign indicating the problem should be placed on the machine to communicate its status to affected personnel.
Safe Operating Procedures
Machine users will follow safe operating procedures as developed and enforced by the machine custodian or supervisor in charge. An example of a written program containing acceptable safe operating procedures is available (see Tools, Machine Safeguarding Safe Operating Procedure Topics).
Accident risks can be reduced with adequate machine safeguarding. Identifying obvious and hidden hazards should be the first step in planning and reviewing the need for machine tool safeguarding. The information presented in this chapter should be considered as a starting point.
Most incidents leading to injury are the result of inadvertent or unwise contact with moving machine parts. Because of the great diversity of machine designs and functions, appropriate safeguarding to protect workers from such hazards may also have numerous forms. Certain principles, however, are basic to any effective safeguarding design.
Machine Safeguarding Evaluation and Design
A uniform process should be applied and used to evaluate each of the hazards on the machine to develop the required level of safeguarding. The evaluation can be performed by a knowledgeable and experienced person internal to SLAC, or for more complicated machine designs and safeguarding issues, the evaluation can be conducted by a qualified third party.
The OSHA/ANSI hierarchy for controlling machine hazards is as follows:
Eliminate the hazard by design
Control the hazard by guarding or devices
Warnings
Personal protective equipment
Training
If the results of the hazard evaluation show the equipment to be safe (that is, poses no hazard to the employee), changes to the equipment may not be necessary. This may be true for manually-powered equipment.
See Tools, Machine Safeguarding Design Considerations, for further explanations and information.
General Safeguarding Methods and Options
See Tools, Machine Safeguarding General Methods and Options, for general ideas and approved types of guards and devices.
Equipment-specific Techniques
See Tools, Machine Safeguarding Equipment-specific Techniques, for information on the recommended techniques for the guarding of specific types of machines.
Equipment Maintenance
Machine custodians will establish and follow a program of periodic and regular inspections and maintenance of their equipment to ensure that machines, parts, and auxiliary equipment are in a safe operating condition and necessary safeguards are present. Records of these inspections should be maintained and made available for inspection upon request.
Only authorized personnel will be permitted to maintain or repair machine tools. When service occurs that requires entry of any body part into a danger zone within the equipment, or unexpected startup or energizing of the machine could cause injury, maintenance personnel will first isolate hazardous energies as required by the SLAC Lock and Tag Program for the Control of Hazardous Energy.
Other Requirements
Positive Disconnecting Means
To enable proper isolation of hazardous energies before and during equipment maintenance and repair, machines and equipment operated by electric motors or other hazardous energy will be provided with a positive disconnecting means. Examples of positive disconnecting means include quick disconnect knife switches, circuit breakers, valves, and power cords and plugs. Push buttons, selector switches, software interlocks, control circuit type devices, and computer controlled software cannot be used to isolate hazardous energy.
Stop Buttons and Power Controls
Machines should have an emergency power off (EPO) or stop button or other readily-accessible and clearly designated power switch within easy reach of the operator to cut off the power to each machine. The power controls must be located so as to make it unnecessary to reach over or near the hazard to make adjustments. For larger machines, power switches should be located in multiple locations on various sides so that power can be easily deactivated by bystanders in case of emergency.
Machine Anchoring
Machines designed for a fixed location will be securely anchored to prevent walking or moving due to vibration, rotation, or seismic activity.
Manual Reset
Proper restart systems must be installed on all powered equipment and tools so that manual reset is required to restart the tool after it has been stopped by any safety device or mechanism. For example, if an interlocked guard stops tool operation when the guard is removed, manual reset is required to restart the tool after the guard is replaced. Replacing the guard alone must not allow the tool to restart. Manual reset is typically achieved by requiring the tool operator to press a reset button in order to restart the tool.
Anti-Restart Devices
Anti-restart devices (ARDs) or other effective provisions must be present on all woodworking machines and mechanical power presses which could create hazardous conditions to employees if motors were to suddenly restart after a restoration of voltage conditions following a power failure. It is strongly recommended that any machine that could pose a hazard to employees upon restoration of power also be provided with an ARD. Although there is no explicit regulatory requirement for metal working or other machines to have ARDs, the machines should at a minimum be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL) and conform to the applicable standard in the American National Standards Institute B11 series (see Resources)
In addition, the machine should be evaluated (see above Section, “Machine Safeguarding Evaluation and Design”) to determine the risk to employees if an ARD is not present. A sudden restoration of power following an interruption should not create hazardous conditions to employees. (See Tools, Machine Safeguarding Anti-restart Devices, for more information and detailed requirements.)
Malfunctioning Machinery or Safeguards
Malfunctioning machinery or safeguards must be reported immediately to the area supervisor or machine custodian. If the malfunction presents a safety hazard, the machine must be taken out of service by disconnecting and locking out the power source(s). A warning sign indicating the problem should be placed on the machine to communicate its status to affected personnel.
Safe Operating Procedures
Machine users will follow safe operating procedures as developed and enforced by the machine custodian or supervisor in charge. An example of a written program containing acceptable safe operating procedures is available (see Tools, Machine Safeguarding Safe Operating Procedure Topics).
6.procedure on accident investigation
What is an accident and why should it be investigated?
The term "accident" can be defined as an unplanned event that interrupts the completion of an activity, and that may (or may not) include injury or property damage.
An incident usually refers to an unexpected event that did not cause injury or damage this time but had the potential. "Near miss" or "dangerous occurrence" are also terms for an event that could have caused harm but did not.
Reasons to investigate a workplace accident include:
· most importantly, to find out the cause of accidents and to prevent similar accidents in the future
· to fulfill any legal requirements
· to determine the cost of an accident
· to determine compliance with applicable safety regulations
· to process workers' compensation claims
Incidents that involve no injury or property damage should still be investigated to determine the hazards that should be corrected. The same principles apply to a quick inquiry of a minor incident and to the more formal investigation of a serious event.
Please note: The term incident is used in some situations and jurisdictions to cover both an "accident" and "incident". It is argued that the word "accident" implies that the event was related to fate or chance. When the root cause is determined, it is usually found that many events were predictable and could have been prevented if the right actions were taken -- making the event not one of fate or chance (thus, the word incident is used). For simplicity, we will use the term accident to mean all of the above events.
The information that follows is intended to be a general guide for supervisors or joint occupational health and safety committee members. When accidents are investigated, the emphasis should be concentrated on finding the root cause of the accident rather than the investigation procedure itself so you can prevent it from happening again. The purpose is to find facts that can lead to actions, not to find fault. Always look for deeper causes. Do not simply record the steps of the event.
Who should do the accident investigating?
Ideally, an investigation would be conducted by someone experienced in accident causation, experienced in investigative techniques, fully knowledgeable of the work processes, procedures, persons, and industrial relations environment of a particular situation.
Some jurisdictions provide guidance such as requiring that it must be conducted jointly, with both management and labour represented, or that the investigators must be knowledgeable about the work processes involved.
In most cases, the supervisor should help investigate the event. Other members of the team can include:
· employees with knowledge of the work
· safety officer
· health and safety committee
· union representative, if applicable
· employees with experience in investigations
· "outside" expert
· representative from local government
Should the immediate supervisor be on the team?
The advantage is that this person is likely to know most about the work and persons involved and the current conditions. Furthermore, the supervisor can usually take immediate remedial action. The counter argument is that there may be an attempt to gloss over the supervisors shortcomings in the accident. This situation should not arise if the accident is investigated by a team of people, and if the worker representative(s) and the members review all accident investigation reports thoroughly.
Why look for the "root cause"?
An investigator who believes that accidents are caused by unsafe conditions will likely try to uncover conditions as causes. On the other hand, one who believes they are caused by unsafe acts will attempt to find the human errors that are causes. Therefore, it is necessary to examine some underlying factors in a chain of events that ends in an accident.
The important point is that even in the most seemingly straightforward accidents, seldom, if ever, is there only a single cause. For example, an "investigation" which concludes that an accident was due to worker carelessness, and goes no further, fails to seek answers to several important questions such as:
· Was the worker distracted? If yes, why was the worker distracted?
· Was a safe work procedure being followed? If not, why not?
· Were safety devices in order? If not, why not?
· Was the worker trained? If not, why not?
An inquiry that answers these and related questions will probably reveal conditions that are more open to correction than attempts to prevent "carelessness".
What are the steps involved in investigating an accident?
The accident investigation process involves the following steps:
· Report the accident occurrence to a designated person within the organization
· Provide first aid and medical care to injured person(s) and prevent further injuries or damage
· Investigate the accident
· Identify the causes
· Report the findings
· Develop a plan for corrective action
· Implement the plan
· Evaluate the effectiveness of the corrective action
· Make changes for continuous improvement
As little time as possible should be lost between the moment of an accident or near miss and the beginning of the investigation. In this way, one is most likely to be able to observe the conditions as they were at the time, prevent disturbance of evidence, and identify witnesses. The tools that members of the investigating team may need (pencil, paper, camera, film, camera flash, tape measure, etc.) should be immediately available so that no time is wasted.
What should be looked at as the cause of an accident?
Accident Causation Models
Many models of accident causation have been proposed, ranging from Heinrich's domino theory to the sophisticated Management Oversight and Risk Tree (MORT).
The simple model shown in Figure 1 attempts to illustrate that the causes of any accident can be grouped into five categories - task, material, environment, personnel, and management. When this model is used, possible causes in each category should be investigated. Each category is examined more closely below. Remember that these are sample questions only: no attempt has been made to develop a comprehensive checklist.
Figure 1: Accident Causation
Task
Here the actual work procedure being used at the time of the accident is explored. Members of the accident investigation team will look for answers to questions such as:
· Was a safe work procedure used?
· Had conditions changed to make the normal procedure unsafe?
· Were the appropriate tools and materials available?
· Were they used?
· Were safety devices working properly?
· Was lockout used when necessary?
For most of these questions, an important follow-up question is "If not, why not?"
Material
To seek out possible causes resulting from the equipment and materials used, investigators might ask:
· Was there an equipment failure?
· What caused it to fail?
· Was the machinery poorly designed?
· Were hazardous substances involved?
· Were they clearly identified?
· Was a less hazardous alternative substance possible and available?
· Was the raw material substandard in some way?
· Should personal protective equipment (PPE) have been used?
· Was the PPE used?
· Were users of PPE properly trained?
Again, each time the answer reveals an unsafe condition, the investigator must ask why this situation was allowed to exist.
Environment
The physical environment, and especially sudden changes to that environment, are factors that need to be identified. The situation at the time of the accident is what is important, not what the "usual" conditions were. For example, accident investigators may want to know:
· What were the weather conditions?
· Was poor housekeeping a problem?
· Was it too hot or too cold?
· Was noise a problem?
· Was there adequate light?
· Were toxic or hazardous gases, dusts, or fumes present?
Personnel
The physical and mental condition of those individuals directly involved in the event must be explored. The purpose for investigating the accident is not to establish blame against someone but the inquiry will not be complete unless personal characteristics are considered. Some factors will remain essentially constant while others may vary from day to day:
· Were workers experienced in the work being done?
· Had they been adequately trained?
· Can they physically do the work?
· What was the status of their health?
· Were they tired?
· Were they under stress (work or personal)?
Management
Management holds the legal responsibility for the safety of the workplace and therefore the role of supervisors and higher management and the role or presence of management systems must always be considered in an accident investigation. Failures of management systems are often found to be direct or indirect factors in accidents. Ask questions such as:
· Were safety rules communicated to and understood by all employees?
· Were written procedures and orientation available?
· Were they being enforced?
· Was there adequate supervision?
· Were workers trained to do the work?
· Had hazards been previously identified?
· Had procedures been developed to overcome them?
· Were unsafe conditions corrected?
· Was regular maintenance of equipment carried out?
· Were regular safety inspections carried out?
This model of accident investigations provides a guide for uncovering all possible causes and reduces the likelihood of looking at facts in isolation. Some investigators may prefer to place some of the sample questions in different categories; however, the categories are not important, as long as each pertinent question is asked. Obviously there is considerable overlap between categories; this reflects the situation in real life. Again it should be emphasized that the above sample questions do not make up a complete checklist, but are examples only.
How are the facts collected?
The steps in accident investigation are simple: the accident investigators gather information, analyze it, draw conclusions, and make recommendations. Although the procedures are straightforward, each step can have its pitfalls. As mentioned above, an open mind is necessary in accident investigation: preconceived notions may result in some wrong paths being followed while leaving some significant facts uncovered. All possible causes should be considered. Making notes of ideas as they occur is a good practice but conclusions should not be drawn until all the information is gathered.
Injured workers(s)
The most important immediate tasks--rescue operations, medical treatment of the injured, and prevention of further injuries--have priority and others must not interfere with these activities. When these matters are under control, the investigators can start their work.
Physical Evidence
Before attempting to gather information, examine the site for a quick overview, take steps to preserve evidence, and identify all witnesses. In some jurisdictions, an accident site must not be disturbed without prior approval from appropriate government officials such as the coroner, inspector, or police. Physical evidence is probably the most non-controversial information available. It is also subject to rapid change or obliteration; therefore, it should be the first to be recorded. Based on your knowledge of the work process, you may want to check items such as:
· positions of injured workers
· equipment being used
· materials or chemicals being used
· safety devices in use
· position of appropriate guards
· position of controls of machinery
· damage to equipment
· housekeeping of area
· weather conditions
· lighting levels
· noise levels
· time of day
You may want to take photographs before anything is moved, both of the general area and specific items. Later careful study of these may reveal conditions or observations missed previously. Sketches of the accident scene based on measurements taken may also help in subsequent analysis and will clarify any written reports. Broken equipment, debris, and samples of materials involved may be removed for further analysis by appropriate experts. Even if photographs are taken, written notes about the location of these items at the accident scene should be prepared.
Eyewitness Accounts
Although there may be occasions when you are unable to do so, every effort should be made to interview witnesses. In some situations witnesses may be your primary source of information because you may be called upon to investigate an accident without being able to examine the scene immediately after the event. Because witnesses may be under severe emotional stress or afraid to be completely open for fear of recrimination, interviewing witnesses is probably the hardest task facing an investigator.
Witnesses should be kept apart and interviewed as soon as possible after the accident. If witnesses have an opportunity to discuss the event among themselves, individual perceptions may be lost in the normal process of accepting a consensus view where doubt exists about the facts.
Witnesses should be interviewed alone, rather than in a group. You may decide to interview a witness at the scene of the accident where it is easier to establish the positions of each person involved and to obtain a description of the events. On the other hand, it may be preferable to carry out interviews in a quiet office where there will be fewer distractions. The decision may depend in part on the nature of the accident and the mental state of the witnesses.
Interviewing
Interviewing is an art that cannot be given justice in a brief document such as this, but a few do's and don'ts can be mentioned. The purpose of the interview is to establish an understanding with the witness and to obtain his or her own words describing the event:
DO...
· put the witness, who is probably upset, at ease
· emphasize the real reason for the investigation, to determine what happened and why
· let the witness talk, listen
· confirm that you have the statement correct
· try to sense any underlying feelings of the witness
· make short notes or ask someone else on the team to take them during the interview
· ask if it is okay to record the interview, if you are doing so
· close on a positive note
DO NOT...
· intimidate the witness
· interrupt
· prompt
· ask leading questions
· show your own emotions
· jump to conclusions
Ask open-ended questions that cannot be answered by simply "yes" or "no". The actual questions you ask the witness will naturally vary with each accident, but there are some general questions that should be asked each time:
· Where were you at the time of the accident?
· What were you doing at the time?
· What did you see, hear?
· What were the environmental conditions (weather, light, noise, etc.) at the time?
· What was (were) the injured worker(s) doing at the time?
· In your opinion, what caused the accident?
· How might similar accidents be prevented in the future?
If you were not at the scene at the time, asking questions is a straightforward approach to establishing what happened. Obviously, care must be taken to assess the credibility of any statements made in the interviews. Answers to a first few questions will generally show how well the witness could actually observe what happened.
Another technique sometimes used to determine the sequence of events is to re-enact or replay them as they happened. Obviously, great care must be taken so that further injury or damage does not occur. A witness (usually the injured worker) is asked to reenact in slow motion the actions that preceded the accident.
Background Information
A third, and often an overlooked source of information, can be found in documents such as technical data sheets, health and safety committee minutes, inspection reports, company policies, maintenance reports, past accident reports, formalized safe-work procedures, and training reports. Any pertinent information should be studied to see what might have happened, and what changes might be recommended to prevent recurrence of similar accidents.
What should I know when making the analysis and conclusions?
At this stage of the investigation most of the facts about what happened and how it happened should be known. This has taken considerable effort to accomplish but it represents only the first half of the objective. Now comes the key question--why did it happen? To prevent recurrences of similar accidents, the investigators must find all possible answers to this question.
You have kept an open mind to all possibilities and looked for all pertinent facts. There may still be gaps in your understanding of the sequence of events that resulted in the accident. You may need to reinterview some witnesses to fill these gaps in your knowledge.
· When your analysis is complete, write down a step-by-step account of what happened (your conclusions) working back from the moment of the accident, listing all possible causes at each step. This is not extra work: it is a draft for part of the final report. Each conclusion should be checked to see if:
· it is supported by evidence
· the evidence is direct (physical or documentary) or based on eyewitness accounts, or
· the evidence is based on assumption.
This list serves as a final check on discrepancies that should be explained or eliminated.
Why should recommendations be made?
The most important final step is to come up with a set of well-considered recommendations designed to prevent recurrences of similar accidents. Once you are knowledgeable about the work processes involved and the overall situation in your organization, it should not be too difficult to come up with realistic recommendations. Recommendations should:
· be specific
· be constructive
· get at root causes
· identify contributing factors
Resist the temptation to make only general recommendations to save time and effort.
For example, you have determined that a blind corner contributed to an accident. Rather than just recommending "eliminate blind corners" it would be better to suggest:
· install mirrors at the northwest corner of building X (specific to this accident)
· install mirrors at blind corners where required throughout the worksite (general)
Never make recommendations about disciplining a person or persons who may have been at fault. This would not only be counter to the real purpose of the investigation, but it would jeopardize the chances for a free flow of information in future accident investigations.
In the unlikely event that you have not been able to determine the causes of an accident with any certainty, you probably still have uncovered safety weaknesses in the operation. It is appropriate that recommendations be made to correct these deficiencies.
The Written Report
If your organization has a standard form that must be used, you will have little choice in the form that your written report is to be presented. Nevertheless, you should be aware of, and try to overcome, shortcomings such as:
· If a limited space is provided for an answer, the tendency will be to answer in that space despite recommendations to "use back of form if necessary."
· If a checklist of causes is included, possible causes not listed may be overlooked.
· Headings such as "unsafe condition" will usually elicit a single response even when more than one unsafe condition exists.
· Differentiating between "primary cause" and "contributing factors" can be misleading. All accident causes are important and warrant consideration for possible corrective action.
Your previously prepared draft of the sequence of events can now be used to describe what happened. Remember that readers of your report do not have the intimate knowledge of the accident that you have so include all pertinent detail. Photographs and diagrams may save many words of description. Identify clearly where evidence is based on certain facts, eyewitness accounts, or your assumptions.
If doubt exists about any particular part, say so. The reasons for your conclusions should be stated and followed by your recommendations. Weed out extra material that is not required for a full understanding of the accident and its causes such as photographs that are not relevant and parts of the investigation that led you nowhere. The measure of a good accident report is quality, not quantity.
Always communicate your findings with workers, supervisors and management. Present your information 'in context' so everyone understands how the accident occurred and the actions in place to prevent it from happening again.
What should be done if the investigation reveals "human error"?
A difficulty that has bothered many investigators is the idea that one does not want to lay blame. However, when a thorough worksite accident investigation reveals that some person or persons among management, supervisor, and the workers were apparently at fault, then this fact should be pointed out. The intention here is to remedy the situation, not to discipline an individual.
Failing to point out human failings that contributed to an accident will not only downgrade the quality of the investigation. Furthermore, it will also allow future accidents to happen from similar causes because they have not been addressed.
However never make recommendations about disciplining anyone who may be at fault. Any disciplinary steps should be done within the normal personnel procedures.
How should follow-up be handled?
Management is responsible for acting on the recommendations in the accident investigation report. The health and safety committee, if you have one, can monitor the progress of these actions.
Follow-up actions include:
· Respond to the recommendations in the report by explaining what can and cannot be done (and why or why not).
· Develop a timetable for corrective actions.
· Monitor that the scheduled actions have been completed.
· Check the condition of injured worker(s).
· Inform and train other workers at risk.
· Re-orient worker(s) on their return to work
Introduction
Accidents occur when hazards escape detection during preventive measures, such as a job or process safety analysis, when hazards are not obvious, or as the result of combinations of circumstances that were difficult to foresee. A thorough accident investigation may identify previously overlooked physical, environmental, adminstrative, or process hazards, the need for new or more extensive safety training, or unsafe work practices. The primary focus of any accident investigation should be the determination of the facts surrounding the incident and the lessons that can be learned to prevent future similar occurrences.
Scope and Application
All accidents should be investigated. The depth and complexity of the investigation will vary with the circumstances and seriousness of the accident. The Supervisor or other individual responsible for operations involved in an accident should ensure that an investigation is conducted and that when appropriate, corrective actions are taken.
Program Description
The first priority whenever an accident occurs is to deal with the emergency and ensure that any injuries or illnesses receive prompt medical attention. The accident investigation should begin immediately thereafter. This ensures that details of what occurred will be fresh in people’s minds and that witnesses don’t influence one another by talking about the accident. It also minimizes the likelihood that important evidence is not moved, lost, taken, destroyed, or thrown away before the scene has been thoroughly inspected.
Types of Accidents
Accidents fall into two categories, serious and non-serious. Non-serious accidents do not cause lost workdays even though the worst that could happen did happen. Examples of these include paper cuts, minor scratches or abrasions, or system failures that have minor consequences, such as a low-pressure hose that ruptures and sprays cool water. Serious accidents include both those which did involve lost workdays and those which might have. This second type of serious accident is called a "near miss." Examples of near misses with serious injury potential include:
A worker twists an ankle in a fall from a low scaffold (this could easily have been a broken leg or worse);
A worker tips back in a chair and topples backward (backward falls are always serious because head injury might result);
A worker turns on a machine and gets a slight shock (shock from voltage potential greater than 75 volts DC or 40 volts AC is considered serious).
After an accident or near miss occurs, supervisors should contact EHS. All serious accidents, those involving lost workdays or near misses, should be investigated with the same thoroughness.
Who Should Investigate
Supervisors should note initial details of the incident and contact EHS to schedule an interview with the injured employee. Regardless of the type of investigation, the supervisor should be involved for the following reasons:
Supervisors have a responsibility to provide their workers with a safe and healthful workplace;
Supervisors know the workers and their work better than anyone else and are in the best position to gather the facts and find a practical solution to the problem;
The supervisor’s involvement can help promote better relations with workers by demonstrating concern for their safety and attention to accident prevention.
Accident Investigate Approach
As with most other tasks, skill in conducting effective accident investigations improves with experience. A good basic approach is to find out what caused the accident and what can be done to prevent or minimize the chances of a similar accident occurring. Some suggestions that may help supervisors get the facts and reach a conclusion include:
Maintain objectivity throughout the investigation. Its purpose is to find the cause of the accident, not to assign blame for its occurrence.
Check the accident site and circumstances thoroughly before anything is changed.
Discuss the accident with the injured person, but only after first aid or medical treatment has been given (see Section A1, Work-Related Injuries and Illnesses). Also talk with anyone who witnessed the accident and those familiar with conditions immediately before and after it occurred.
Be thorough. Small details may point to the real cause.
Reconstruct the events that resulted in the accident, considering all possible causes. Determine unsafe conditions or actions that separately or in combination were contributing factors.
What To Do With The Results
Supervisors should take action to control or eliminate the conditions that caused the accident once these have been conclusively identified. EHS can provide assistance in determining the level of action that may be necessary, such as the following:
When equipment changes or safeguards are necessary, supervisors should discuss specific recommendations with Department management;
When an operation can be changed to eliminate the hazard, supervisors should make the change if it is within their authority, or seek the necessary approval from Department management;
If unsafe acts by workers are involved, ensure that the worker is properly trained and that training is followed. All others involved in similar operations should be trained as well.
Return to Top
Roles and Responsibilities
Department
Ensure accidents involving their operations or workers are investigated.
Ensure corrective actions are taken.
Supervisors
Particpate in incident investigations.
Take corrective actions.
EHS
Investigate incidents promptly and thoroughly.
Issue accident investigation reports.
Provide training in investigation methods and techniques when requested.
Individual
Cooperate with supervisors and others during investigations.
reference
http://web.princeton.edu/sites/ehs/healthsafetyguide/a2.htm
5.issues on how to protect the environment
Ideas to Help * Sort out your rubbish. Organic matter e.g. potato peelings, left over food, tea leaves etc. can be transferred straight to a compost heap in the garde and used as a good, natural fertiliser for the plants. Aluminium cans, glass bottles and newspapers etc. can be taken to bottle and can banks and wastepaper skips. Find out where they are by asking your local council or library. * Use recycled paper to help save trees. Everyone in Britain uses about 6 trees worth of paper every year. Chlorine bleach is usually used to make newspapers and this pollutes rivers. Its better to use unbleached, recycled paper whenever you can. * Take your old clothes to charity shops. Some are sold, others are returned to textile mills for recycling. * Try to avoid buying plastic. It's hard to recycle. One way to cut down on plastic is to refuse to use carrier bags offered by supermarkets and use strong, long lasting shopping bags instead, or re-use plastic bags over and over again, until they wear out. * Don't buy over-packed goods. Many things we buy have unnecessary amounts of plastic and paper around them.RainforestsRainforests are valuable habitats. About half of all the species of animals and plants in the world live in rainforests. Thousands of rainforest plants contain substances that can be used in medicines and the tribal people of the forests have great knowledge of them. Rainforests are being cut down to make way for 'civilised man', to grow crops and graze cattle, and provide timber. An area almost the size of Britain is burnt every year. Rainforests help to regulate the world's climate and atmosphere.Ideas to Help * Never buy products made up of tropical hardwoods e.g. mahogany and teak. It is better to buy only pine, oak, ash or beech because they can be replaced. * Garden and flower shops sometimes sell rainforest orchids that have been imported. If you buy an orchid, check that it has been grown in Britain. * Some parrots and macaws are unfortunately still imported. If you want a parrot as a pet, make sure it has been hatched in Britain. * Eating a beefburger may be helping to destroy the rainforest! Most burgers in Britain are made from European cattle. However, the cattle are often fed on soya bean and a lot of that comes from Brazil where large areas of forest have been destroyed to make soya fields. Before buying a burger, ask where the cattle came from and what they were fed on. Try a veggie burger for a change!PollutionThe air, water and soil of habitats all over the world have been, and are still being,polluted in many different ways. This pollution affects the health of living things. Air is damaged by car and lorry fumes, and power stations create acid rain which destroys entire forests and lakes. When fossil fuels i.e. oil, gas and coal are burned to provide energy for lighting, cooking etc. they form polluting gases.Oils spills pollute sea water and kill marine life; chemical waste from factories and sewage works, and artificial fertilisers from farmland, pollute river water, killing wildlife and spreading disease.The careless or deliberate dumping of litter in the environment is not only unsightly but dangerous too.Ideas to Help * Use less energy by switching off lights when rooms are not in use, not wasting hot water, not overheating rooms and not boiling more water than necessary when making a cup of tea! * Use a bicycle or walk instead of using a car for short trips. * If you spot pollution, such as oil on the beach, report it to the local council. If you suspect a stream is polluted, report it to the local Environmental Health Officer * If you use chlorine-based bleach or detergents containing phosphates you are contributing to water pollution. Try to buy 'environmentally-friendly' products.The Ozone LayerFifteen to thirty miles above the Earth lies the stratosphere, a broad band of gases and one of these gases is ozone. It's only a small part of the stratosphere but very important because it prevents too many of the sun's ultra violet rays from reaching us. Too many ultra violet rays can give us skin cancer and destroy plankton, the important microscopic life in the sea. In the 1980s it was discovered that 'holes' were appearing in the ozone layer above the Antarctic and Arctic. CFCs, chlorofluorocarbons, gases used in the manufacture of aerosols and fridges, are believed to be responsible for destroying the ozone layer.Ideas to Help * Don't buy aerosols containing CFCs. Actually, it's not a good idea to buy any aerosols. Even 'ozone friendly' aerosols may contain harmful chemicals and spray cans are difficult to dispose of - they cannot be recycled. Pump-action sprays are a much better alternative. * A lot of packaging e.g. fast-food cartons, are polystyrene 'blown' with CFCs. Try to avoid items packed with this polystyrene. * If you know of anyone getting rid of an old fridge, tell them that the CFCs can be drained out and recycled - contact the local council and they will dispose of the fridge safely. New fridges can be bought with less CFCs in them.Certain gases in the atmosphere, mainly carbon dioxide, methane and CFCs, act like the glass in a greenhouse, allowing sunlight through to heat the Earth's surface but trapping some of the heat as it radiates back into space. Without this the Earth would be frozen and lifeless. However, owing to Man's activities,'greenhouse gases' are building up in the atmosphere, causing a greater amount of heat to be reflected back to Earth. The result is an increase in average world temperatures and in the future this could lead to the flooding of cities world wide and more hurricanes etc. Ideas to Help * Don't waste electricity. Electricity is produced by burning coal, oil and gas and this action gives off carbon dioxide. * Car fumes produce carbon dioxide and nitrogen oxide - so try to cut down on car journeys if possible. Use a bike or walk - it's good exercise for you too! * Recycle as much of your waste as you can. Methane, the most effective 'greenhouse gas', is released into the air as the rubbish in landfill sites rots.Endangered Habitats and their WildlifeWild habitats all over the world are fast disappearing. Forests are being cut down, rivers and seas polluted, heathlands built on, hedgerows pulled up, ponds filled in - the destruction seems endless. As the habitats decrease, so do their communities of animals and plants. Habitat destruction is one of the main reasons why many species face extinction. Other reasons include the hunting of animals and collection of plants.There are now more than 5, 000 species of animal and about 25,000 species of plants threatened with extinction. During the last 200 years more than 200 species of mammals and birds have become extinct i.e. disappeared from the earth forever. It is possible that we are losing one species of animal or plant every day!Ideas to Help * In many countries souvenirs made from rare wildlife are available - never buy shells, coral or things made from elephant ivory, rhino horn or cat skin etc. * Remember that British habitats and wildlife are under threat too. The destruction of wood land, pollution of rivers and ponds, the use of pesticides and herbicides have all contributed to the reduction in the amount of wildlife in Britain. Many animals and plants are endangered e.g. red squirrels, otters, barn owls, golden eagles, natterjack toads, many species of butterflies and dragonflies, orchids - to name just a few. If you have a garden at home, you could transform it into a mini nature reserve for wildlife. The same could be done in your school grounds. Here are just a few ideas to create a wildlife garden:- 1. Make a pond. Even A small pond will attract frogs and toads etc.. Birds and foxes may use it for drinking. 2. Make a wildflower meadow. Wildflower plants and seeds may be bought from garden suppliers and, if planted correctly, a colourful meadow will result, attracting birds, butterflies and other insects. 3. Provide logs and stones and allow a few autumn leaves to remain lying around. These provide shelter for minibeasts and perhaps small mammals such as shrews and mice. An over-neat garden will not be attractive to wildlife. 4. Feed the birds during winter and put up nest boxes for robins and blue tits etc. to use in spring. 5. If your garden is big enough, you could plant a small wood. Always grow native trees such as oak, ash or birch - these attract more insects than foreign trees. 6. Hedgehogs are useful to have in the garden as they eat slugs. Encourage them to stay by providing them with tinned cat or dog meat, water and a safe place to hibernate in winter, such as a pile of logs, stuffed with hay and leaves. 7. Avoid using chemical sprays in the garden - some of these can be poisonous to wildlife. It's best to let the birds eat the cabbage-munching caterpillars, the hedgehogs and toads deal with the lettuce-loving slugs and the ladybirds dine on the rose-ravaging greenfly!
2. communication rules on safety
Communication hazard
Definition
Hazard communication is addressed in specific standards for the general industry, shipyard employment, marine terminals, longshoring, and the construstion industry.
1910.1200(a)(1)
The purpose of this section is to ensure that the hazards of all chemicals produced or imported are evaluated, and that information concerning their hazards is transmitted to employers and employees. This transmittal of information is to be accomplished by means of comprehensive hazard communication programs, which are to include container labeling and other forms of warning, material safety data sheets and employee training.
Definition
Hazard communication is addressed in specific standards for the general industry, shipyard employment, marine terminals, longshoring, and the construstion industry.
1910.1200(a)(1)
The purpose of this section is to ensure that the hazards of all chemicals produced or imported are evaluated, and that information concerning their hazards is transmitted to employers and employees. This transmittal of information is to be accomplished by means of comprehensive hazard communication programs, which are to include container labeling and other forms of warning, material safety data sheets and employee training.
1.safety guidelines
SAFETY GUIDELINES
A.safety guidelines for High Voltage and/or Line Powered Equipment
These guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage.
Note that the danger to you is not only in your body providing a conducting path, particularly through your heart. Any involuntary muscle contractions caused by a shock, while perhaps harmless in themselves, may cause collateral damage. There are likely to be many sharp edges and points inside from various things like stamped sheet metal shields and and the cut ends of component leads on the solder side of printed wiring boards in this type of equipment. In addition, the reflex may result in contact with other electrically live parts and further unfortunately consequences.
The purpose of this set of guidelines is not to frighten you but rather to make you aware of the appropriate precautions. Repair of TVs, monitors, microwave ovens, and other consumer and industrial equipment can be both rewarding and economical. Just be sure that it is also safe!
Don't work alone - in the event of an emergency another person's presence may be essential.
Always keep one hand in your pocket when anywhere around a powered line-connected or high voltage system.
Wear rubber bottom shoes or sneakers.
An insulated floor is better than metal or bare concrete but this may be outside of your control. A rubber mat should be an acceptable substitute but a carpet, not matter how thick, may not be a particularly good insulator.
Wear eye protection - large plastic lensed eyeglasses or safety goggles.
Don't wear any jewelry or other articles that could accidentally contact circuitry and conduct current, or get caught in moving parts.
Set up your work area away from possible grounds that you may accidentally contact.
Have a fire extinguisher rated for electrical fires readily accessible in a location that won't get blocked should something burst into flames.
Use a dust mask when cleaning inside electronic equipment and appliances, particularly TVs, monitors, vacuum cleaners, and other dust collectors.
Know your equipment:
TVs and monitors may use parts of the metal chassis as ground return yet the chassis may be electrically live with respect to the earth ground of the AC line. Microwave ovens use the chassis as ground return for the high voltage. In addition, do not assume that the chassis is a suitable ground for your test equipment!
If circuit boards need to be removed from their mountings, put insulating material between the boards and anything they may short to. Hold them in place with string or electrical tape. Prop them up with insulation sticks - plastic or wood.
If you need to probe, solder, or otherwise touch circuits with power off, discharge (across) large power supply filter capacitors with a 2 W or greater resistor of 100 to 500 ohms/V approximate value (e.g., for a 200 V capacitor, use a 20K to 100K ohm resistor). Monitor while discharging and/or verify that there is no residual charge with a suitable voltmeter. In a TV or monitor, if you are removing the high voltage connection to the CRT (to replace the flyback transformer for example) first discharge the CRT contact (under the insulating cup at the end of the fat red wire). Use a 1M to 10M ohm 1W or greater wattage resistor on the end of an insulating stick or the probe of a high voltage meter. Discharge to the metal frame which is connected to the outside of the CRT. For TVs and monitors in particular, there is the additional danger of CRT implosion - take care not to bang the CRT envelope with your tools. An implosion will scatter shards of glass at high velocity in every direction. There is several tons of force attempting to crush the typical CRT. Always wear eye protection. While the actual chance of a violent implosion is relatively small, why take chances? (However, breaking the relatively fragile neck off the CRT WILL be embarrassing at the very least.)
Connect/disconnect any test leads with the equipment unpowered and unplugged.
Use clip leads or solder temporary wires to reach cramped locations or difficult to access locations.
If you must probe live, put electrical tape over all but the last 1/16" of the test probes to avoid the possibility of an accidental short which could cause damage to various components. Clip the reference end of the meter or scope to the appropriate ground return so that you need to only probe with one hand.
Perform as many tests as possible with power off and the equipment unplugged. For example, the semiconductors in the power supply section of a TV or monitor can be tested for short circuits with an ohmmeter.
Use an isolation transformer if there is any chance of contacting line connected circuits.
A Variac(tm) (variable autotransformer) is not an isolation transformer! However, the combination of a Variac and isolation transformer maintains the safety benefits and is a very versatile device. See the document "Repair Briefs, An Introduction", available at this site, for more details. The use of a GFCI (Ground Fault Circuit Interrupter) protected outlet is a good idea but may not protect you from shock from many points in a line connected TV or monitor, or the high voltage side of a microwave oven, for example. (Note however, that, a GFCI may nuisance trip at power-on or at other random times due to leakage paths (like your scope probe ground) or the highly capacitive or inductive input characteristics of line powered equipment.) A GFCI is also a relatively complex active device which may not be designed for repeated tripping - you are depending on some action to be taken (and bad things happen if it doesn't!) - unlike the passive nature of an isolation transformer. A fuse or circuit breaker is too slow and insensitive to provide any protection for you or in many cases, your equipment. However, these devices may save your scope probe ground wire should you accidentally connect it to a live chassis.
When handling static sensitive components, an anti-static wrist strap is recommended.
However, it should be constructed of high resistance materials with a high resistance path between you and the chassis (greater than 100K ohms). Never use metallic conductors as you would then become an excellent path to ground for line current or risk amputating your hand at the wrist when you accidentally contacted that 1000 A welder supply!
Don't attempt repair work when you are tired. Not only will you be more careless, but your primary diagnostic tool - deductive reasoning - will not be operating at full capacity.
Finally, never assume anything without checking it out for yourself! Don't take shortcuts!
A.Safety guidelines for building electronics equipments.
This give you some guidelines how to to make your homebuilt electronics equipments safe. I have tried to make those guidelines to be as caaurate as possible. However, I do not assume, and hereby claim, any liability to any party for any loss or damage, direct or consequential, caused by errors in those guidelines.
The safety requirements refer mainly to the 230V mains voltage and European electrical safety requirements.
Basics
Equipments must be designed and built so that they do not cause danger to the operator or the environment in the normal operation or in case of equipment damage. Especially take ce of the shielding against electrical shocks, high temperatures, explosion and fire.
There are two classes of insulation:
Class I: single insulation which requires three core mains cable with earth
Class II: double insulation which requires no earth
Class I characteristics
Insulation between mains and every touchable part must withstand flashover voltage of 2120V
The distance between mains voltage carrying parts and touchable parts must be at least 3 mm
All touchable conducting parts must be properly earthed
Class II characteristics
Insulation between mains and every touchable part must withstand flashover voltage of 4240V
The distance between mains voltage carrying parts and touchable parts must be at least 6 mm If you are designing electronics product you should aim for making your products class II. They are easier to sell abroad. If you need to provide the equipment as class 1 you should be very clear in the installation instructions of the correct methods for wiring the equipment to a supply.
1.Practical considerations on building safe equipments .
All the parts in the equipment which carry dangerous voltage must be protected so that nobody can touch them. There must not be possible to expose any dangerous voltage carrying parts without using tools to open the equipment.
2.Keep the distance between mains carrying parts and other parts as large as possible.
The distance between mains carrying parts and other parts must not be in any case less than what is required.
3.Try to make the mains carrying parts as compacts as possible.
Use approved parts for mains carrying parts of the circuit (mains etry, fuse holder and switch)
If you do not use an intergrated entry, use strain relief on the mains cable entry point. You must also provide some mechanical protection between the mains cable and the equipment case.
The wires from the mais cable must not be directly soldered to the circuit board.
The gounding wire must be connected so that it will be disconnected last if for some reason the strain relief in the mains cable gets loose.
All wires inside equipment which carry mains voltage must use wire approved for this kind of application.
Use preferably double-pole mains switch in all your circuits. Single pole mains switch is allowed only on equipment that is powered by transformers with isolated promary and secondary windings.
4.Fuses and mains interference supperssors are not needed to be switched off.
Use only the approved color coded wires for carrying the mains voltage. The green/yellow colored wire can be only used as grounding wire.
Fusing
1.Generally all equipments need fuse.
2.Short-circuit proof transformers do not need a promary fuse.
3.Use only approved fuse holders.
It is advisable (though not mandatory) to precede the mains switch with a fuse.
Every fuse must have a label stating the it's rating and type.
The rating of a slow fuse should not be greater than 1.25 times the normal operating current of the equipment.
Every equipment must have a label stating the identity of the equipment, the mains voltage and mains frequency. If the equipments works only on AC power then there must be a symbol stating that. It is a good practice to put also the equipment mains current and/or power rating in that label.
In case of failure the equipment should not be a danger to the user.
Temperature of touchable parts must not be so high that they can cause injury or create a fire risk. The fuse is to prevent overheating or fire hazard in case of a short. The protection for user is not by fuses, instead the ground bonding for the class 1 and double/reinforsed insulation for class II would be to ensure the protection of user against electrical shock.
Mechanical construction
Mechanical construction of the equipment must be sturdy to withstand the equipment operating conditions.
Repeately dropping the equipment onto a hard surface from height of 50 mm must not cause damage.
Greater impacts must not loosen the mains transformer, electrolytic capacitors and other important components.
Materials
Do not ise dubious or flammable materials.
Do not use material which emit poisonous gasses.
The case must be made of such material that does not burn by itself.
Special details on building Class II equipments
Use mains cable with moulded plug.
Use good strain relief on mains cable.
Use an approved mains on/off switch which does not have a metal lever.
Push wires through the eyelets and solder.
Use insulating sleeves to provide extra protection.
The distance between transformer and other parts must be at least 6 mm.
Use wire with insulation of 4 mm or more and core diameter of at least 0.75 mm.
The circuit board must be secured firmly.
Use preferably insulating plastic case.
The equipment label must have the indication that the equipment is double insulated (two squares symbol).
When the power switch is not required ?
Power on/off switch is nit required if the power consumption of the equipments is less than 10W or if the equipment is intended for continuous use.
An on/off switch not in the mains circuit is allowed if the transformer has isolated promary and secondary coils and power consumption in "off" position is less than 10W. There must be a visible indication that the equipment is plugged in.
Information sources
Safety Guidelines for Elektor Electronics magazine. This article is published in very manu Elektro Electronics magazine issues. The article I used is form Elektor Electornics 4/1996 page 53.
Olavi Hokkinen, Sähköturvallisuuohjeet, Suomen Radioamaööriliitto, 1984, 12 s.
Some additional tips when operating with line powered electronic circuits
Three rules when working with line powered electronics equipments
Rule 1: switch the power off
Rule 2: work with one hand
Rule 3: keep the other hand behind your back That way you live longer when you work with mains powered equipments. Failing to follow all 3 rules may shorten your life span.
Additional safety tips when operating with mains powered equipments
Always be very careful when operating with line powered equipments
Use mains isolation transformer always when you must work with equipments when they are powered
If you can't use mains isolation transformer when use Ground Fault Interrupter (GFCI) for your own safety.
To make sure that the power is disconnected do it twice for safety: switch the equipment off and remove the power cord.
When you power down the equipment wait some time to let the dangerous voltage carrying capacitors to discharge. Make sure that the large capacitors are discharged then you start to operate with the equipment (discharge them if necessary).
Do not wear anything which can fall inside equipments and cause short circuits.
reference
http://www.epanorama.net/documents/safety/safety_guidelines.html
Subscribe to:
Posts (Atom)