What is the standard distance of the limited approach in dealing with arc flash and shock hazard?
What is the standard distance of the limited approach in dealing with arc flash and shock hazard?
Limited Approach Boundary – The Limited Approach Boundary (LAB) is identified as the “distance from an exposed energized electrical conductor or circuit part within which a shock hazard exists”. Best practice if for any unqualified person to stay 42” (3′ 6”) or more away from the hazard.
How much space do you generally need to protect yourself from arc flash?
Generally 18 inches is assumed to be the distance between a worker’s face/chest and the arc-flash.
What are the three limits of approach boundaries?
The NFPA 703® recognizes three arc flash boundary levels: the limited approach boundary, the restricted area, and the prohibited area boundary.
What is required in a limited approach boundary?
The limited approach boundary is the minimum distance from the energized item where unqualified personnel may safely stand. No untrained personnel may approach any closer to the energized item than this boundary.
What are the requirements to cross the limited approach boundary?
It is the approach limit for unqualified persons. Unqualified persons may only cross this boundary if they are under the direct supervision of a qualified person, and wearing the appropriate personal protective equipment for the hazards involved.
What is an arc flash limited approach boundary?
Limited Approach: An approach limit at a distance from an exposed live part where a shock hazard exists. This distance is not common between equipment. Some equipment will have a greater flash protection boundary while other equipment will have a lesser boundary.
What is electrical working distance?
Basically, the working distance is the distance between you and the point of origin of an arc flash. The point of origin for an arc flash will typically be inside a piece of electrical equipment, at an energized conductor or bus. A typical working distance for low voltage equipment might be 18 inches.
How are arc flash boundaries typically determined?
Calculating an arc flash boundary is going to be based on the voltage of the equipment that would cause the arc flash. Most companies will use software programs where they can enter in the voltage information about a piece of equipment, and it will calculate the arc flash boundary automatically.
