Understanding the Arc Flash Boundary is critical in electrical safety, particularly as outlined by NFPA 70E, the Standard for Electrical Safety in the Workplace. This boundary delineates the distance from an arc source where the incident energy is equal to 1.2 cal/cm² (5 J/cm²). Understanding and correctly applying this definition is vital for ensuring the safety of personnel working around electrical systems that can potentially release hazardous energy.

By defining and respecting the arc flash boundary, workplaces significantly enhance safety for electricians, technicians, and any personnel working near energized electrical systems.

The following definitions can be found in Article 100 of NFPA 70E:

Below is a sample of NFPA 70E. For the complete section, see the actual NFPA 70E text at NFPA.ORG. Once there, click on the free access link to NFPA 70E.

Balaclava.  An arc-rated head-protective fabric that protects the neck and head except for a small portion of the facial area.

Informational Note: Some balaclava designs protect the neck and head area except for the eyes while others leave the eyes and nose area unprotected.

Barrier. A physical obstruction that is intended to prevent contact with equipment or energized electrical conductors and circuit parts.

Bonded (Bonding). Connected to establish electrical continuity and conductivity.

Bonding Conductor or Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

Boundary, Arc Flash (Arc Flash Boundary). When an arc flash hazard exists, an approach limit from an arc source at which incident energy equals 1.2 cal/cm² (5 J/cm²).