Arc flash boundary definition3/18/2024 The Restricted Approach Boundary may only be crossed by a qualified worker. However, when the arc flash boundary is larger, be sure proper arc flash PPE is worn within the limited approach boundary. In many cases the limited approach boundary is the farthest electrical boundary that exists. To cross the limited approach boundary a worker must be qualified or otherwise escorted by a qualified person. No matter who crosses the Arc Flash Boundary, proper PPE is required that meets the requirements of the NFPA 70E.ĭistance from an exposed live part within which a shock hazard exists. Detailed formulas for determining the arc flash boundary can be found in the NFPA 70E and IEEE 1584.īoth Qualified and Non-qualified can cross the Arc Flash Boundary as long as long as Qualified personnel supervision is present. This boundary is calculated based upon specific system information, and can apply when exposed energized conductors or circuit parts are present, or with doors and equipment closed if interacting in a manner that could cause an arc. It is defined as the distance at which a worker is exposed to 1.2 calories/cm2 of incident energy, which represents the onset of a second degree burn. The Arc Flash Boundary deals specifically with arc flash hazards and determines when arc flash PPE shall be required. These boundaries are not calculated and apply only when exposed energized conductors or circuit parts are present. The Limited, and Restricted approach boundaries deal strictly with shock prevention and are based upon nominal system voltage. The arc flash boundary has a primary purpose of preventing burn injury due to arc flash incidents. The third boundary is the arc flash boundary. Two boundaries deal specifically with shock hazards and are intended to prevent shock and electrocution. The NFPA 70E defines three boundaries for electrical workers to observe.
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