Circuit for Emergency Lighting Unit Equipment

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dkidd

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here
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PE
NEC 700.12(F) requires that emergency lighting unit equipment be powered by the branch circuit powering the normal lighting in an area. The exception allows it to be powered by a different branch circuit if the normal lighting in an area is powered by a minimum of three branch circuits. If the lighting in an area is powered by only two branch circuits, would unit equipment be required on each of the two lighting circuits. Can anyone provide a reference to a source of an interpretation?
 

steve66

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Illinois
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Engineer
NEC 700.12(F) requires that emergency lighting unit equipment be powered by the branch circuit powering the normal lighting in an area. The exception allows it to be powered by a different branch circuit if the normal lighting in an area is powered by a minimum of three branch circuits. If the lighting in an area is powered by only two branch circuits, would unit equipment be required on each of the two lighting circuits. Can anyone provide a reference to a source of an interpretation?

It depends. If one branch circuit covers lighting throughout the area, then unit equipment on that circuit is enough. If one circuit covers the north half of the room, and the other covers the south half, then you would want unit equipment in the north half on that circuit, and same for the south half.

The whole idea is just to avoid the situation where the normal lighting goes out (ie. one branch breaker trips), but the unit lighting doesn't come on because it doesn't see the power outage.

So ask yourself, if the power goes out, or if either breaker trips, will there still be enough lighting (either normal or unit equipment) on to exit? If the answer is yes, you should be OK.
 
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