What is Arc Flash?

Arc Flash Shock Hazard

An arc flash is a release of electrical energy from an electrical system that occurs during certain types of arc fault. When the release of electrical energy occurs, an arc travels either from one conductor to another or to ground through the air; it happens quickly and lasts until the circuit is broken, usually by built-in protective mechanisms.

When work is performed on live or damaged equipment, there is a higher risk for an arc blast. This happens because the isolation between electrified conductors or the insulation isn’t adequate. Activities that are more likely to lead to an explosion are installing/removing fuses and installing/removing circuit breakers. The Occupational Safety and Health Administration (OSHA) explains that other common causes of arc flash events include condensation, corrosion, dust, or dropping a conductive tool.

Why is arc flash a cause for concern?

These events are very hazardous: they result in temperatures upwards of 35,000 degrees Fahrenheit and create pressure waves called arc blasts. The extreme temperatures of these explosions can cause serious thermal burns and melt or even vaporize the metal conductors. The corresponding blast creates a pressure wave that can knock people over and collapse lungs. The noise associated with this type of event can even rupture eardrums.

Second and third-degree burns are common injuries associated with arc flash, and according to OSHA, the severity of injuries depends on three things: the proximity of the explosion, the temperature, and how much time it takes the circuit to break.

Standards exist to reduce common electrical hazards, and it is important to follow these regulations to prevent accidents. In this post we’ll examine a key component of electrical safety compliance that informs workers of the hazard present: arc flash hazard labeling.

Arc Flash Safety

Preventing these types of explosions from occurring requires an electrical safety program that emphasizes training, personal protective equipment, and labels that communicate the severity of present electrical hazards.


Detailed information about these topics can be found in the National Fire Protection Association’s guidelines, NFPA 70E: Standard for Electrical Safety in the Workplace®. This document, which was originally created by the NFPA at OSHA’s request, is a comprehensive guide to electrical safety topics including arc flash.

While OSHA regulations do not specifically state workplaces must comply with NFPA 70E, it is possible for OSHA to cite employers who do not follow the standard. This is because NFPA 70E is an industry consensus standard, meaning it outlines the best practices for dealing with a recognized hazard. Because arc flashes are a recognized hazard, employers must take the necessary steps (outlined in 70E) to prevent it. This includes making compliant hazard labels, properly labeling your facility, providing PPE, and training employees.

Arc Flash Labels

Labeling electrical equipment with arc flash warning labels is critical for alerting workers of potential hazards. Labels will need to be clearly displayed on electrical equipment  and feature an orange warning header with a safety alert symbol. These warning labels are specific to arc flashes and includes relevant information like the measured arc flash boundary, arc flash rating, required personal protective equipment, and the flash hazard category.

Additional Resources