A webinar I did for Mission Criticalon August 22nd inspired me to publish some FAQs about the subject of electrical safety. I included some questions asked by our audience during and after the event and many I have been asked over the years.

The word safety has become an overused cliché. We talk about safety, we read about safety, we have meetings about safety, but do our actions support our words? Use the following information to evaluate your organization’s safety culture.

Electrical shock and arc flash are the two primary types of electrical safety hazard in your workplace.

• Electrical shock occurs when the human body becomes part of an energized electrical circuit. The degree of injury is directly related to the path the current takes


through the body. As little as 1 milliamp is enough to cause death.

• Arc flash is literally a fireball that ignites when an energized conductor unintentionally connects to another energized conductor or ground. The air within the sphere of the established arc becomes conductive, and the arc grows exponentially until such time as current is interrupted.


Some 40,000 electrical fires occur in the U.S. each year. Five or six arc flash and shock incidents take place each day. Human error is the major cause of these incidents. While human error can never be completely eliminated, it is possible to reduce the likelihood of such occurrences by establishing a corporate culture of safety, adopting a zero tolerance policy, training personnel, and focusing on safety.

Question:Where should we start?

Answer: Review your safety SOP, safety training program, personal protective equipment (PPE) inventory, arc-flash hazard analysis, and other information about your facility’s electrical infrastructure. Is all information available, correct, and current? Are all personnel fully qualified and trained? You may be surprised to find your fundamental records are incomplete or dated. The reliability of your facility and personnel safety is directly linked to the quality of this essential information. Enlist the services of a safety professional to assist you with this review and identify action items.

Question:Where do we find safety information?

Answer:NFPA 70 (the National Electrical Code), NFPA 70E (the Standard for Electrical Safety in the Workplace), and OSHA 1910 are the primary sources of electrical safety information, regulatory requirements, and guidelines.


Standards are recognized and accepted guidelines, not statutes. Statutory enforcement comes from federal, state, and local building and safety codes. So although OSHA does not directly enforce the NFPA 70E standard, OSHA considers the NFPA standard a recognized industry practice. The employer is required to conduct assessment in accordance with CFR 1910.132(d)(1). Employers who conduct the hazard/risk assessment as stated in the NFPA 70E standard are deemed in compliance with the Hazard Assessment and Equipment Selection OSHA standard.

Question:Who is responsible for electrical safety?

Answer:Everyone is responsible to a point. Adopt a corporate culture of safety with zero tolerance for infractions and appoint or hire a safety professional to focus on your safety program and assume responsibility for contractors and others working in your mission critical space.

Question:What is a shock?

Answer:Electrical shock is a term broadly applied to the body’s reaction to electric current. A small amount of current (100 mA) may cause severe injury or death. Some of the reactions to shock are involuntary. Muscles may contract and cause one to become locked onto the energized point. Physical injury may also occur as a result of a fall triggered by muscular reaction to electrical current.

Table 1, NFPA 70E, 130.7, illustrates how the human body reacts to certain current ranges.

Table 1

There are variables to consider. The severity of the injury caused by electrical shock is directly related to how the body is connected to the circuit. Current takes the path of least resistance to ground or another return path. A current path across the chest is the most dangerous. Other factors, such as standing in water, perspiration, mechanical clearance, or body position, can also affect the amount of current the body is subjected to and the degree of effect experienced.

With involuntary muscle contractions, falls are an added hazard. The area directly adjacent to the work must be clear of clutter.

Question:How can you determine how much current the human body would be subjected to in the event of a shock?

Answer:You can apply the basic Ohm’s Law formula E = IR

E = Nominal Voltage

I = Current

R = Resistance (the human body is believed to be about 1000 ohms)

Therefore, on a simple household 120-volt circuit the calculation would be:

I=E/R,  I = 120/1000 = 0.120 amps

According to the table, the physical effect would be extreme pain, respiratory arrest, and severe muscular contraction.

Electrical safety is not an option. This topic is broad and complex and requires the allocation of significant resources to establish a comprehensive program. Four to five injuries or deaths occur each day in the U.S. as a result of electrical shock or arc flash. You can debate the difference between standards and statutes; however, the standards are the basis for statutes and codes.

One industry study concludes the minimum cost of an arc flash event is $750,000. I would submit that it is likely to be a lot higher when you consider the direct damage to the equipment and facility, the liability as a result of injury or death, and the business disruption. As a facility manager, you could be held personally liable in the event of an incident if you fail to enforce safe work practices for your employees and contractors. In a court of law or the court of public opinion, you’ll fare much better having done the right thing. It’s time to get serious about electrical safety in every facility. Protect your employees, your contractors, and your company. 


Reprints of this article are available by contacting Jill DeVries at devriesj@bnpmedia.com or at  248-244-1726.