240.21(C)(4)(b) Interpretation

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philly

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In a situation where a transformer is located outdoors and 480V secondary conductors are routed inside to a 480V SWBD is there a specific limitation on distance for considering "nearest the point of entrance of the conductors"?

For instance if the conductors are routed into an electrical room but travel in overhead conduit 30ft within the room to get to the SWBD can that be considered "nearest the point of entrance" or does the SWBD have to literally be right where the conduits enter the room?

This appears to be one of those areas of NEC that may be open to interpretation so looking for opinions from others?

Also is there anything in the NEC that considers allowances for a temporary installation (This is the case here)?

Has anyone ever heard of a requirement to provide PE sealing for a temporary installation?
 
To me "nearest" means exactly that...you enter the building and drop directly into the equipment. I would not accept 30'.

There is no specific permission to do this in Article 590 for temporary and that article says:
" Except as specifically modified in this article, all other requirements of this Code for permanent wiring shall apply to temporary wiring installations. "
This would be a question for your AHJ.
 
It would be an AHJ call here also. Historically here conductors routed in rigid or IMC located IN the electrical room and in no way subjectb to damage are give some latitude but I've never seen 30ft accepted.
 
The safety issue is unprotected cable inside a building. Conduits aren't the same thing a s short-circuit protection. I'd put a temporary fused switch either on the transformer or at the point of entry. Then don't bother with the conduits.
 
Yeah I can't see 30ft being acceptable in most situations. I think you'd need a convincing explanation for why the electrical room wasn't arranged such that the switchboard was nearest the outside wall. Unless 30ft is the size of the switchgear. 😎
 
Thanks for the responses.

I received some additional info from site today that the temporary SWBD is located in an outdoor pit (with cover) that surrounds the electrical room in the basement. This is located at a large hospital and this outdoor Pit is essentially like a moat on the outside of the electrical room in the basement that allows for equipment access outside of the electrical room in order to crane it to the parking lot (ground level) above.

So with that said that leads me to the question of what is the delineation between and outdoor and indoor location? To me this outdoor pit would be considered "outdoors" since it is outside of the electrical room and would not be considered an interior structure. In that case the conductors would be ran entirely outdoors and thus allow the provisions of NEC conductor protection to be satisfied?
 
philly said:
... To me this outdoor pit would be considered "outdoors" since it is outside of the electrical room and would not be considered an interior structure. In that case the conductors would be ran entirely outdoors and thus allow the provisions of NEC conductor protection to be satisfied?
Click to expand...

Bingo!
 
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