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What is an Arc Flash?

03 February, 2023


When electrical current jumps through the air between two points, it's called an arc. We've all experienced a small arc at some point in our lives remember the last time you reached for a metal doorknob and felt a shock? That was an arc. Lightning works the same way, but with a lot more power.

With high-powered electrical equipment, an unexpected arc can cause an explosive burst of heat and light. It's like lightning in a box and it's called an arc flash.

Because of the deadly power involved, any equipment that poses a risk of an arc flash needs to be labeled with a warning. Everyone who works with that equipment should be aware of the danger, and know what they need to do to stay safe.

The most widely-used standard for arc flash labeling is NFPA 70E, and it has a very specific requirement when it comes to what goes on the label.

The NFPA 70E guidelines requires the following items on every arc flash label:

- The Nominal System Voltage,

- The Arc Flash Boundary, and

- At least one of the following:

- Either the available incident energy and working distance, or the NFPA's Arc Flash PPE Category for the equipment

- The minimum arc rating of clothing required, or

- A site-specific description of the PPE required.

If you want more information, check out What Is An Arc Flash article. For comprehensive literature about Arc Flash label requirements, NFPA 70E or to ensure compliant electrical labeling at your facility, check out our library of free Arc Flash Guides.