Articles 700 and 517

[charlie b]

Exactly how are they related, if at all?

This is not my scenario:

• Existing commercial building.
• Existing backup generator, with 600 amp breaker at the source.
• Existing “emergency switchboard.” It has two 400 amp breakers.
• One breaker serves “emergency” (Article 700) loads via an ATS.
• The other breaker serves “optional standby” (Article 702) loads via a separate ATS.

I would suspect this of being a violation of 700.10(B). I don’t think it would satisfy the Exception to sub paragraph (5)(b), in that I doubt the 600 amp and 400 amp breakers could be selectively coordinated. Let us assume, for the present, that they cannot.

This is my scenario:

• Same as above, except that it is a hospital.
• Same distribution as above, except that one ATS serves “critical branch” loads and the other serves “equipment branch” loads.

517.30(C)(1) has rules about separation of wiring. But they are not as detailed or explicit as we see in article 700. Am I seeing a violation? Can you even cite a violation of article 700 in a hospital, or does it even apply at all?

 

[don_resqcapt19]

700 only applies to the "life safety branch" in a 517 application.

517.26 Application of Other Articles
The life safety branch of the essential electrical system shall meet the requirements of Article 700, except as amended by Article 517.

 

[steve66]

700 only applies to the "life safety branch" in a 517 application.

And I believe (at least in the newer NEC editions), the selective coordination requirements in 700 do not apply to a hospital.

The selective coordination requirements for a hospital are in 517, and are a less stringent than the requirements in 700.

And is this an existing system, or a new install? Many of these emergency systems were installed before the selective coordination requirements.

 

[charlie b]

Thanks Don and Steve. This is an existing situation, installed well before the selective coordination rule was added to the NEC. But I am adding load to this system, and I am mentally preparing myself to deal with a potential AHJ question about complying with current code.