What is Arc Flash?

Arc flash is one of those things that you just have to see to believe. The video linked here shows what happens when an arc flash occurs (start at ~37 seconds).

Preventing and mitigating the effects of arc flash go hand in hand with accurately sizing equipment for fault currents. Equipment that is accurately rated will have a lesser chance of causing serious damage to equipment and personnel.

When a fault occurs in an electrical system one of the possibly outcomes is an arc flash. An arc flash is a discharge of high amounts of energy. While its impossible to completely prevent arc flashes from occurring we can calculate the maximum amount of energy that can be discharged at any given panelboard, distribution board etc. This information is the result of an arc flash study.

Why is this important?

While, for smaller panelboards the maximum possible incident energy is typically quite small, as the system grows in size and complexity the incident energy discharge can reach extremely dangerous levels. As the amount of potential energy discharge grows extra precautions must be taken when working on or about the equipment. Arc flash warning labels (like the one shown here) outline what those precautions must be to maintain safety. They will indicate the hazard level and appropriate personnel protective equipment (PPE) that someone will need when working in or about that equipment.