Big foot. The Loch Ness Monster. Arc flashes.

They all seem to have some mystery surrounding them. As much as I’d like turn this into a blog about monster hunting in the BC interior, let’s demystify the topic that Mr. Levitt would approve of.

What is an arc flash?

An arc flash is an electrical explosion caused by the accidental release of electrical energy from two conductive sources (e.g. wires) across an air gap (meaning they are spaced apart and not connected). Arc flashes are hazardous for a number of reasons:

  • They heat up to 19,426 °C – nearly as hot as a lightning bolt!
  • Make sound exceeding 160 dBA – the same volume as a space shuttle launching
  • Create pressure waves up to 2,000 lbs per square foot
  • Cause electrical shock
  • Molten metal
  • Create blinding light

What is a Calorie?

Arc flashes are measured in calories per centimeter squared which is the amount of energy that it will take to increase the temperature of 1 gram of water 1 °C at standard air pressure. The amount of energy released in an electrical explosion is referred to incident energy. It is important that your protective clothing stands up to the incident energy in order to avoid injuries.
As a reference point, a second degree skin burn develops are 1.2 cal/cm2 which is the equivalent to holding your finger 1 cm above a lighter for 1 second.

How common are arc flash injuries?

Arc flashes are very rare events. Studies have shown that electrical shocks (while rare themselves) are more common of an electrical injury than arc flashes. A study by the National Institute for Occupational Safety and Health states that there were 44,363 electrical-related injuries from 1992 through 2001. Of that number, 17,101 injuries were caused by arc flash burns.
While this shows that electrical injuries are rare events, a study by NIOSH states that electrical burn injuries cause more work-lost time, accounting for a disproportionate number of work lost days. Specifically related to workplace deaths, the chances of dying due to an arc flash is as high as 1 in 10.

What causes arc flashes?

Human errors cause the majority of arc flashes whether, usually as a result of using of a non-insulated tool, dropping a conductive item in the enclosure or improper maintenance of the equipment or enclosure (accumulation of conductive dust or not replacing worn components) while working on energized systems that are typically above 208V.
This is why many of the top employers are placing a premium on finding ways to eliminated stress while working in arc flash clothing. For tips and suggestions for finding the appropriate arc flash suits, view our page on arc flash PPE.

What Health and Safety requirements are there?

A workplace should follow a written standard in the development of an electrical safety program. CSA Z462 or NFPA 70E are good starting points for the development of an electrical safety program.

In Canada, you should have someone that is appointed to control your electrical safety program and put in place the proper control measures through a “lock out, tag out” program that de-energizes equipment (if possible) whenever maintenance is being performed.

All electrical hazards should be identified and labeled accordingly. Electrical labels are required to state the voltages, arc flash boundaries and approach limits, the strength of an arc flash at cal/cm2 and the necessary PPE required.

Need help putting together your electrical safety program? Let us know. We can help you perform an electrical hazard analysis and establish lockout procedures to create a custom program for your workplace.

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Eric Huard

Market Segment Manager, Personal Safety

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