question for bob alexander

[petersonra]

Is there any reason I can't use article 504 to protect a main enclosure and a remote jbox connected by rigid w/ wiring and w/o seals if I put the pressure source at the main enclosure and the vent at the jbox?

I never actually used conduit that had wiring in it before for this purpose, but I can't find anything that would prohibit it.

 

[petersonra]

Is there any reason I can't use article 504 to protect a main enclosure and a remote jbox connected by rigid w/ wiring and w/o seals if I put the pressure source at the main enclosure and the vent at the jbox?

I never actually used conduit that had wiring in it before for this purpose, but I can't find anything that would prohibit it.

I don't know what I was thinking. I was working on an IS system this morning and had a brain fart.

What I really want to do is pressurize the whole system using the existing conduit. Nothing to do with article 504.

 

[rbalex]

Well, since you cleared up the Article 504 part .

Pressurizing through the raceway system is conceptually recognized (obscurely) within the general application in Section 500.7(D). The references in NEC Section 501.15(A)(2) and NFPA 496 Section 4.2.3 are also a bit vague. There is a slightly better explanation in the NFPA 497, Annex A, Explanatory Material Section A4.2.3

 

[petersonra]

I never really considered this before but if I was careful about how I routed it it might be possible to protect field devices by pressuring them through the conduit. Could eliminate the need for at least some seals.

Of course if the guy had bought class 1 div 1 switches in the first place instead of div 2 switches, it would not be an issue.