What is Arc Flash?

An Arc Flash or an Electric Arc is the rapid and dangerous release of energy due to an electrical arcing fault. It happens in a fraction of a second – even faster that you can blink your eye and can have devastating consequences for anyone exposed.


Confined Flash

Confined Arc Flash

This happens when an Arc Flash occurs in a distribution box or a motor control centre. The flash is contained on all sides except the front opening of the box. All of the focused energy escapes through the only opening onto the hands and face of the person working on the box.

Open Flash

Open Flash

Takes place when an Arc Flash occurs in an open space with the energy escaping 360° in all directions. The molten metal can ignite the PC and PPE of the worker.


The intensity of the Arc Flash is influenced not only by the voltage. An Arc Flash will contain the release of thermal energy, acoustical energy, pressure wave and debris.

The variables that affect the size and energy of an electric Arc Flash are:

Arc Flash Intensity

  • Voltage (safety issue where greater than 220 Volts)
  • Amperage
  • Arc Gap
  • Closure Time
  • Distance away from the arc
  • 3 Phase v Single Phase
  • Confined Space


The consequences of an Arc Flash can be devastating depending on the intensity of the Arc Flash, the proximity of the individual to the source of the arc and the PPE used if any.

Injuries can include:

Arc Flash caused Injury

  • 3rd degree (irreversible) burns caused by extreme heat and molten splatter
  • Loss of sight due to electromagnetic radiation
  • Internal burns and intoxication due to inhalation of hot toxic gases
  • Permanent hearing damage due to explosion bang
  • Other physical trauma caused by the explosion (blast pressure and flying debris)
  • Death


There are many methods of protecting personnel from Arc Flash hazards. This can include personnel wearing Arc Flash PPE or modifying the design and configuration of electrical equipment. The best way to remove the hazards of an Arc Flash is to deenergize electrical equipment when interacting with it, however de-energizing electrical equipment is in and of itself an Arc Flash hazard.