The prohibited approach boundary (PAB) is the distance away from a piece of energized electrical equipment . The distance of the boundary is determined by the amount of voltage running through the equipment.
What are the three limits of approach boundaries?
Under NFPA 70E, there are three boundaries that are observed— limited approach, restricted approach, (the shock protection boundaries) and arc flash boundary .
Which approach limit is at the point where work is the same as making contact with the live part?
Restricted Approach: An approach limit at a distance from an exposed live part which there is an increased risk of shock. Prohibited Approach (inner boundary): A distance from an exposed part which is considered the same as making contact with the live part. This distance is not common between equipment.
What are the four limits of approach boundaries?
- Flash protection boundary (outer boundary) The flash protection boundary is the farthest established boundary from the energy source. ...
- Limited approach boundary. ...
- Restricted approach boundary.
What determines the limited approach boundary?
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.
What are the two shock boundaries?
There are two shock protection boundaries; the Limited Approach Boundary (LAB) and the Restricted Approach Boundary (RAB), and one Arc Flash Boundary (AFB) that must be established in order to provide a safe distance for personnel from exposed, energized electrical components.
How many approach boundaries are there?
Under NFPA 70E, there are three boundaries that are observed—limited approach, restricted approach, (the shock protection boundaries) and arc flash boundary.
What are the conditions for a person to cross the restricted approach boundary?
To cross the Restricted Approach Boundary into the Restricted Space, the qualified person (who has completed required training) must wear appropriate PPE . Also, he/she must have a written approved plan for the work to be performed and plan the work to keep all parts of the body out of the Prohibited Space.
What is the maximum current level a human can withstand without getting injured?
The amount of internal current a person can withstand and still be able to control the muscles of the arm and hand can be less than 10 milliamperes (milliamps or mA). Currents above 10 mA can paralyze or “freeze” muscles. When this “freezing” happens, a person is no longer able to release a tool, wire, or other object.
What is the safest ladder to use around electricity?
Electrical Conductivity
For most tasks, an aluminum ladder is ideal; however, if you are working around electricity, you need to use a fiberglass ladder , instead. Unlike its aluminum counterpart, fiberglass ladders are non-conductive, making them the safer choice when working with electricity.
What are the Arc flash boundaries?
Simply put, the arc flash boundary is the distance at which an electrical arc can flash/expand outward , which may endanger employees working on electrical equipment. People that are not adequately protected must stay away from a potential arc flash source by this calculated minimum distance at all times.
Is NFPA 70E a law?
So while the NFPA 70E standard itself is not law , it establishes the safety guidelines which enable employers to comply with OSHA laws dealing with electrical workplace safety and required employee electrical safety training.
How many arc flash boundaries are there?
NFPA 70E is the major industrial standard for safe electrical work in the United States. It defines three protective boundaries around electrical equipment.
Which approach boundary is the closest to the exposed energized parts?
The area closest to the live, exposed equipment is within the restricted boundary . In order to pass this boundary, you must be a qualified worker with the proper training and PPE. If you need to perform work on the energized equipment, you may also need a work permit and documentation.
What is the minimum approach distance when working around exposed live electrical parts?
| Approach distances for qualified person to alternating current | Voltage Range (Phase to Phase) Minimum Approach Distance | Over 750V, not over 2kV 1 ft. 6 in . | Over 2kV, not over 15kV 2 feet | Over 15kV, not over 37kV 3 feet |
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What changes to NFPA 70E were recently adopted?
In the 2018 70E the table was modified to eliminate any clothing or PPE under 1.2 cal/cm2 , because it only deals with arc-rated clothing and other PPE. The table was renamed Table 130.5(G) and put into the body of the standard. Its use is “permitted”, meaning it’s an option—it can be used, but is not mandatory.
