277V in the same conduit as 12V
Ill try to explain this as best as possible. I ran a conduit for some emergency and exit signs which were to be operated with 277. My employer orders me 12v remote emergeny lights instead of the 277 weatherproof as drawn. The GC is okay with this. I have one conduit ran and piped in completely but now have to run another conduit for the 12V according to code. My question is why? If I pulled the 12volt circuit in with the 277v circuit what problems would occur? The 12v circuit is wire rated for 600v. The 12v circuit would not power on until the 277v circuit powers off to turn on the remote heads. Is the induction going to cause problems? Any knowledge helpful, thanks.
Check out 300.3(C) and see if that helps-- also take note of the FPN for 725.136(A). Basically if the 12V is supplied from a class 2 or 3 circuit then you are out of luck
Normally what Dennis pointed out would cover it but in this case you are dealing with an emergency circuit and the rules of Article 700 come into play.
Basically article 700 prohibits an emergency circuit to be run with a non-emergency circuit. The 12 volt circuit from the battery unit to the remote head is an emergency circuit and must be run independently.
As far as the why in this case it is to prevent a fault in a normal circuit from affecting an emergency circuit.
Last edited by iwire; 07-25-12 at 09:08 AM.