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#208941 - 02/23/13 04:09 AM Alarm wiring and power in same J-box.  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
Hey guys thanks for the help on these little issues I
run into. I want to use NEC 300.3 (C)(1)
"Conductors of ac and dc circuits rated 600 volts ,nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. all conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable or raceway."

The voltage is 120/240 a.c. and I want to install the start and alarm conductors in the same J-box box as the power. The alarm cable specified is rated for 300 v. dc.
300.3 (C)(1) only refers to the voltage rating so I'm thinking it's OK even though the alarm conductors are only rated for dc. Right?


2017 / 2014 NEC & Related Books and Study Guides

#209413 - 03/26/13 11:18 PM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 826
Michigan
Read Informational Note #1 .


#209415 - 03/27/13 02:03 AM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
Thanks Yoop. I did see that but the fact that the cable met the voltage requirement but was only rated for DC is what was throwing me off. I usually separate everything but when the GC stubbs the conduits out of the concrete wrong I end up having to make things work. I don't encounter much low voltage and Article 725 still confuses me. One of the things I don't understand is how to accurately classify the circuits when you don't know what the attributes of the power source are in the equipment that is powering them. Is there an easy way to determine that or is it involved?

Last edited by wewire2; 03/27/13 02:05 AM.

#209418 - 03/27/13 11:37 AM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,327
Alaska
What kind of alarm?


"Live Awesome!" - Kevin Carosa

#209419 - 03/27/13 05:37 PM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
For this installation it was generator failure alarms.


#209422 - 03/28/13 08:27 AM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 826
Michigan
725 breaks down each. Class 1/2/ & 3. Take a look.


#209431 - 03/29/13 02:05 PM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
Haha! Got it! I knew I somehow must be missing a step. Totally makes sense now.


#209434 - 03/29/13 06:15 PM Re: Alarm wiring and power in same J-box. [Re: wewire2]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,327
Alaska
Sometimes, that all it takes. Better to talk it out now then have something to smoke out later and get clarity later...


"Live Awesome!" - Kevin Carosa


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