NFPA, OSHA Standards Changes for Arc Flash Addressedtest

By Jeffery C. Camplin

April 2016

Electricity has long been recognized as a serious workplace hazard, exposing employees to electric shock, electrocution, burns, fires, and explosions. The Occupational Safety and Health Administration (OSHA) is using recent changes in best practices for electrical safety in its compliance enforcement related to arc-flash safety.

This change has pushed the arc-flash safety issue back to the forefront for maintenance and engineering departments in institutional and commercial facilities — where it always should be, regardless of regulatory enforcement.

In an arc flash, a flashover of electric current leaves its intended path and travels through the air from one conductor to another or to ground. The results are often violent, and when a human is in close proximity to the arc flash, serious injury and even death can occur.

Arc flash can result from many things, including dust, dropping tools, accidental contact, condensation, material failure, and faulty equipment installation. Three factors determine the severity of an arc-flash injury:

• the proximity of the worker to the hazard

• temperature

• time for circuit to break.

The temperatures of electric arcs can reach 35,000 degrees at the arc terminals, with lethal burns possible at a distance of several feet from the arc and severe burn injuries common at 10 feet. Clothing can ignite at 400-800 degrees Celsius, and arcs can expel droplets of molten terminal metal of 1,000 degrees Celsius or more, burning skin and instantly igniting clothing.

Electrical workers near energized parts of high-fault capacity most often experience arc burns. By one estimate, five to ten arc-flash explosions occur in electrical equipment every day in the United States. Because of the violent nature of an arc-flash exposure, the injury often is serious and can result in death.