What is an Arc Flash Boundary?

What is an Arc Flash Boundary?

An arc flash boundary is the distance at which an electrical arc can flash outward and endanger employees working on electrical equipment. Additional boundary requirements include:

• Conductive Articles of Jewelry and Clothing: Watchbands, bracelets, rings, key chains, necklaces, metal frame glasses, etc. shall not be worn within the restricted approach boundary.
• Working Space: Shall not be used for storage. Space shall be kept clear to permit safe operation and maintenance.
• Barricades: When the arc flash boundary is greater than the limited approach boundary, barricades shall not be placed closer than the arc flash boundary.
• Insulated Tools: Employees shall use insulated tools when working inside the restricted approach boundary of exposed energized electrical conductors.

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).”

Limited approach boundary: “An approach limit at a distance from an exposed energized electrical conductor or circuit part within which a shock hazard exists.”

Restricted approach boundary: “An approach limit at a distance from an exposed energized electrical conductor or circuit part within which there is an increased likelihood of electric shock, due to electrical arc-over combined with inadvertent movement.”