Until 2015, the NFPA also included a Prohibited Approach Boundary. Until the plan is formally approved, no work can be done within this boundary. Before doing so, they need a written plan for the work that will be done in this zone and how it is to be carried out.

Restricted Approach Boundary: Only qualified persons with the right training and appropriate PPE can cross this boundary.

Unqualified personnel can enter only when accompanied and supervised by a qualified person.

Limited Approach Boundary: Only qualified persons wearing appropriate PPE should be authorized to cross this boundary.

No one should be allowed to cross this boundary without appropriate arc-rated PPE.

Arc Flash Protection Boundary: The outer boundary, where a person could suffer a second degree burn if an arc flash event occurred.

The Three Arc Flash BoundariesĪrc flash boundaries are outlined in the NFPA 70E Standard for Electrical Safety in the Workplace. They demarcate arc flash danger zones, ensuring that no one crosses into them unless they have the training, certification, and equipment needed to do so safely. That’s the purpose of the arc flash boundaries. That will involve all the usual control methods: training, arc-rated PPE, and regular maintenance of electrical equipment.īut given how harmful, unpredictable, and quick these events are, one of the best ways to protect workers is to simply ensure they’re not in close proximity when an arc flash happens. Workers need protection from these very serious risks. An arc flash can cause severe burns, damage hearing, knock people off their feet, and propel shrapnel and molten metal through the air. Well, the event is over – its consequences aren’t.

By the time you realize it’s happening, it’s already over.

There’s no time to throw on extra PPE, move out of the way, or even lift your arm to shield your face.

Nfpa 70e arc flash boundary