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Arc Flash

March 29, 2016

The Dangers Of Working With Electricity

An arc flash happens when a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to ground. Known as one of the more dramatic electrical accidents, an arc flash can easily result in a fatality if proper safety precautions are not taken.

During an arc flash incident, temperatures can reach 19,427°C in just 1/1000 of a second. The intensive heat vaporizes metal, causing fatal burns, and producing a blast wave that can collapse lungs and rupture eardrums. Other injuries also occur from shrapnel, toxic gases, and intense ultraviolet rays.

The following factors can affect the severity of an arc flash burn:

  • Incident energy level of the arc
  • Distance from the arc
  • Duration of exposure

Have you ever experienced a shock from a household electric socket? If so, you may recall seeing a flash or hearing an electrical socket pop. Your muscles may have tightened and chances are your injuries were no more than a good scare and a blister on the tip of your finger. Getting shocked from this type of incident is rarely serious, but fatalities are not uncommon.

The risk of fatalities increases tremendously for those working with electrical equipment, the severity and risk of injury is much greater with shocks and burns being the two primary physical hazards. As a result, electrical burns have received greater attention and emphasis from the Occupational Safety and Health Administration (OSHA), National Electric Code (NEC), as well as insurance companies and other groups.

If you’ve seen videos or pictures of arc flash victims, you can testify to the severity of their injuries. Although they are not a pretty sight, they do serve as reminders of the hazards of working with electricity and motivate us to follow safety measures.

To stay safe in the workplace, you need to understand the risks and hazards associated with an arc flash. The following requirements and specifications not only help with developing the complete system design required for short-circuit/coordination studies, but they also allow qualified electrical workers to calculate the magnitude of the hazard and select the appropriate personal protective equipment (PPE), tools, and procedures:

  • OSHA requires equipment owners to properly label all equipment so that it's in compliance with NFPA 70E.
  • The NEC mandates electricians to mark the highest voltage contained within the enclosure on the unit’s cover or door.
  • The Canadian Standards Association and Mine Safety and Health Administration have set specifications and marking requirements for generators, cable, and accessory use.

Before working with electricity, ask yourself the following questions:

  • Is your workplace’s electrical distribution system labelled correctly?
  • Has your workplace performed a short-circuit/coordination study?
  • Does your workplace have one-line diagrams to start the short-circuit/coordination process?
  • Does your workplace have an electrical maintenance program that includes proper settings and verification of protective devices; namely, relays and circuit breakers?
  • Does your workplace have policies and procedures that address arc flash?
  • Do you have the proper PPE and training required to perform electrical maintenance?