Far too many workers are permanently disabled, severely injured or electrocuted each year.

Establishing an effective Electrical Safety Program (ESP) prevents injuries associated with electrical hazards. In addition to legal requirements, the ESP is also key to meeting the requirements of voluntary electrical safety standards including the new CSA Z462.

The ESP and OSHA/OHS Laws

The ESP includes policies, safe work procedures/permits, hazard analysis, risk assessments/reduction, training, personal protective equipment (PPE) and other specific written program documents. The best reason to adopt an ESP is to protect workers from personal injury and prevent property damage.

In addition, OSHA and OHS laws include General Duty clauses that require employers to safeguard workers against recognized hazards. These laws also include regulations requiring employers to take specific measures to prevent electrical hazards. (In my home province of Ontario, regulations for working with electricity have been in place since the 1990s.) The legally required measures are among those that you should incorporate into the ESP.

The ESP and NFPA 70E

However, legal requirements are minimum standards. With an increase in electrical incidents, injuries and fatalities, regulators began to realize that a more comprehensive and focused approach to electrical safety was required. This gave rise to the development of voluntary standards flesh out the minimum requirements for electrical safety set out in the OHS and OSHA laws.

In the U.S., the NFPA (National Fire Protection Association) developed the first nationally recognized standard for electrical safety, entitled NFPA 70E, Standard for Electrical Safety in the Workplace.

The ESP and CSA Z462

Eventually, many organizations in Ontario and other parts of Canada adopted NFPA 70E for their own workplaces. But while NFPA 70E was more fully developed than the legal requirements, it was still largely a U.S. standard.

So the CSA (Canadian Standards Association) used NFPA 70E as a seed document to develop an equivalent Canadian standard. This February, it issued the standard, CSA Z462, Electrical Safety in the Workplace, which harmonizes NFPA 70E with Canadian conditions. Canadians can use the new CSA Z462 standard to evaluate their existing ESP for compliance with provincial regulations and best practices and as a “how-to-do-it” guideline for meeting the requirements of due diligence. Government officials will also likely refer to CSA Z462 to interpret and enforce existing OHS regulations.

The CSA Z462 standard is sometimes referred to as “the arc flash standard.” This is only partly accurate. The elements of Z462—qualifications of individuals who work on or around electrical equipment, safe approach distances, PPE and protective clothing, etc.—are designed to safeguard workers against the risk of both arc flash and live contact shock.

CSA Z462 and Arc Flash/Blast

The electrical hazard many workers fear the most is arc flash/blast. This is understandable. Arc flash produces temperatures in the order of 35,000°C and emits blast pressures equivalent to a large jetliner at full throttle. Other factors, such as impact injuries caused by falling and shrapnel projected toward a worker can cause collateral injuries. Other collateral hazards are copper vapors and hot gases that can lead to immediate serious lung injuries and other long-term health issues such as vision and hearing loss. The effects are akin to a grenade being detonated in your face. The overall hazardous effect of these incidents is often referred to as “toxic energy.”

Unlike the shock approach distances which are based on voltage present, the arc flash distances set out in Z462 are based on the potential thermal incident energy, which is measured in calories per centimeter squared (cal/cm2). Warning and communication labels indicating the information above are placed on panels, switchboards, MCCs, disconnects, etc. These labels form the basis for communicating the safety requirements and PPE ratings to ‘qualified’ electrical workers who must understand, obey and enforce the requirements of these labels implicitly.

CSA Z462 and Live Contact Shock

Live contact shock and not arc flash is the leading cause of electrical injuries. One reason shock is so dangerous is that while many workers fear arc flash, they lack a healthy respect for shock’s potential to harm. Some workers even think that getting shocked is just part of the job! So they flout voltage, particularly 120.

The Analogy: Arc flash is like a plane crash—relatively infrequent, but cataclysmic when it happens. Live contacts are like automobile accidents—they happen all the time, always involve some kind of damage (sometimes inconspicuous) and are occasionally lethal.

Like NFPA 70E, CSA Z462 protects workers from contact with energized fixed electrical equipment and moveable conductors by establishing limits of approach boundaries and spaces (which are incremental safety distances) as follows:

• Limited Approach;
• Restricted Approach; and
• Prohibited Approach.

These approach distances are based on the voltage present, not arc flash/blast distances, which are variable and based on available fault currents and explosive forces, called ‘incident energy’. Complicated calculations—typically performed by competent persons using specialized software—are required for determining the incident energy.

Conclusion

Next week, I’ll look at the other aspects of CSA Z462, including qualified person, meter safety and PPE requirements. Meanwhile, I hope many of you SafetyXChange members will join me for my CSA Z462 audio-conference tomorrow.

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