Arc Flash

What's an Arc Flash?

An arc flash is an undesired release of energy from an electrical system caused by an electrical current leaving its designated path. This current then travels to ground or from one conductor to another through the air. Arc flash temperatures can reach 35,000 degrees and cause life-threatening injuries and catastrophic damage. An arc flash is one of the most dangerous accidents that can occur in a workplace. It’s important to make sure your workers wear arc flash-rated PPE, and that arc flash hazards are properly labeled. Check out our guide for tips on how to protect your facility from arc flash.

Free Arc Flash Labeling E-Book

Free Arc Flash Labeling E-Book

A 19-page guide covering how to correctly label your electrical equipment.

Understanding Arc Flash

What can cause an Arc Flash?

An arc flash usually occurs when there is inadequate insulation or isolation between electrified conductors. Typically this happens because work is being performed on live or damaged equipment. Additional causes of arc flash are:

  • Dust
  • Dropping tools
  • Accidental touching
  • Condensation
  • Material failure
  • Corrosion
  • Faulty Installation
Arc Flash Explosion

Arc Flash Approach / Protection Boundaries

(Updated to reflect 2015 NFPA 70E changes Learn more)

Arc flash boundaries indicate different levels of danger near electrical equipment. The arc flash boundary is the location within which a person could receive second-degree burns. The closer limited approach boundary and restricted approach boundary indicate where increasing risks of electric shock exist. Personnel working near electrified equipment should know where these boundaries are located and what types of personal protective equipment they need to wear within these areas.

Arc Flash Approach

Diagram: Arc Flash Approach / Protection Boundaries. Creative Safety Supply

Restricted Approach Boundary icon

Restricted Approach Boundary

Only Qualified Persons wearing appropriate PPE for the Restricted Approach Boundary, as determined by the Shock Risk Assessment may enter. Must have Energized Electrical Work Permit. (EEWP)

Typical PPE Requirements: Face mask, Flame-resistant gloves, Flame-resistant coveralls, Cotton undergarments

Arc Flash Restricted Approach Boundary
Limted Approach Boundry Icon

Limited Approach Boundary

An unqualified person MAY enter the Limited Approach Boundary, but ONLY if continuously escorted by a Qualified Person, and advised of the potential hazards. Both must be wearing appropriate PPE as determined by a Shock Risk Assessment.

Typical PPE Requirements: Face mask, Flame-resistant gloves, Flame-resistant coveralls, Cotton undergarments

Arc Flash Limited Approach Boundy
Boundry Icon

Arc Flash Boundary

Only Qualified Persons wearing appropriate PPE for the Arc Flash Boundary, as determined by the Incident Energy Risk Assessment may enter.

Typical PPE Requirements: Face mask, Flame-resistant gloves, Flame-resistant coveralls, Cotton undergarments

Arc Flash Boundry

PPE Categories

People working on electrical equipment where an arc flash could occur need to wear the correct level of PPE, which can include arc-rated clothing, gloves, face shields, hearing protection, and even a hood and flash suit. The types of PPE necessary are determined by what PPE category work falls into.

Check out this infographic to learn what the four PPE categories are and what items each category contains.

View infographic

Arc flash and shock hazard label example

In this sample label, the incident energy available and the corresponding work distance (Incident Energy at 18" (cal/cm2): 16.4) is used, so the PPE category is not included. If the PPE category (1-4) were included, this incident energy value would be left off the label.

Arc Flash Label Requirements

Much of the information identified during a risk assessment should be placed on arc flash labels. These labels are affixed to electrical equipment that workers might need to perform work on while it is energized. The labels must meet the NFPA 70E requirements and should follow the formatting guidelines set forth in the ANSI Z535.4 Product Safety Signs and Labels standard.

ANSI-compliant hazard labels include “Warning” or “Danger” signal words as a header along with corresponding symbols and text.

These labels must also include several important pieces of information so workers can understand the arc flash hazard present and behave appropriately. First, the nominal system voltage should be listed. Next, the arc flash boundary, calculated during the risk assessment, should be listed. Finally, a statement about PPE should be included that makes it clear to workers what they should wear. This should be done by listing at least one of the following:

  • The PPE category OR the incident energy available and the corresponding work distance (but not both)
  • The minimum arc rating clothing must have
  • PPE specific to the worksite
  • The method used for calculating this information should also be documented.

Some workplaces choose to include shock hazard information on these labels as well, which can incorporate information about limited and restricted approach boundaries. An assessment date is often included, too.

How to get Arc Flash Labels

Two main methods exist for labeling your electrical equipment with arc flash labels. You can print labels in-house with an industrial label printer. With this method, you can edit label information yourself on your computer and quickly print your labels. If you only need a few arc flash labels, it often makes sense to order custom arc flash labels.

Print your own labels in-house

Option 1

Print your own labels in-house

  • Starting at $0.86 each label
  • No waiting or shipping costs
  • 5 year outdoor life

Shop Arc Flash label printers

Order pre-printed labels

Option 2

Order pre-printed labels

  • Starting at $3.90 each label
  • 5 year outdoor life

Purchase pre-made labels

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