An arc flash is the sudden release of electrical energy through the air when a high–voltage gap exists and there is a breakdown between conductors.
An arc flash gives off thermal radiation (heat) and bright, intense light that can cause burns. Temperatures have been recorded as high as 35,000° F (19,426.6° C). High–voltage arcs can also produce considerable pressure waves by rapidly heating the air and creating a blast. This pressure burst can hit a worker with great force and send molten metal droplets from melted copper and aluminum electrical components great distances at extremely high velocities.

What causes an arc flash?

An arc flash can be spontaneous or result from inadvertently bridging electrical contacts with a conducting object. Other causes may include dropped tools or the buildup of conductive dust or corrosion.

Conditions under which arc flash can occur:

• Working on an energized circuit
• Electrical equipment failure

An Arc flash is sometimes called arc fault or arc blast.

Electrical Safety Regulations

Important safety recommendations: NFPA 70E

• Establish an “electrically safe work condition” before working on a circuit by deenergizing it.
• Create an “electrically safe work condition” by… *
  1. Identifying all power sources,
  2. Interrupting the load and disconnecting power,
  3. Visually verifying that a disconnect has opened the circuit,
  4. Locking out and tagging the circuit,
  5. Testing for voltage, and
  6. Grounding all power conductors
• Use a written permit system for planning and conducting work on or near energized parts.
• Use tools, meters, and other equipment that are suitable for the voltage and current levels present when performing all electrical work.