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#187186 - 06/16/09 08:07 PM 120 vac and 24vdc in same conduit  
shop_test  Offline
Member
Joined: Aug 2008
Posts: 10
California
I cant find this in the NEC.
Is there a reference in the NEC to separate 24vdc and 120 vac into their own conduits?


2017 / 2014 NEC & Related Books and Study Guides

#187197 - 06/17/09 12:13 AM Re: 120 vac and 24vdc in same conduit [Re: shop_test]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 830
Michigan
Try Article 725. 2005 NEC
725.26
725.41
725.55
Depending on the class of the 24volt.


#187206 - 06/17/09 03:24 PM Re: 120 vac and 24vdc in same conduit [Re: Yoopersup]  
shop_test  Offline
Member
Joined: Aug 2008
Posts: 10
California
Thanks for the quick feedback.
Unfortunately I only have the 2008 NEC and 725.26 / 725.55 are no longer listed.


#187222 - 06/17/09 07:11 PM Re: 120 vac and 24vdc in same conduit [Re: shop_test]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 830
Michigan
2008 NEC Article 725
725.48
725.136
Try thoses
Also read Article 725 Definitions for
Classes 1,2,3.


#187226 - 06/17/09 08:07 PM Re: 120 vac and 24vdc in same conduit [Re: Yoopersup]  
shop_test  Offline
Member
Joined: Aug 2008
Posts: 10
California
Thanks.
It looks like the answer is yes it is acceptable for our situation.


#187254 - 06/18/09 12:30 PM Re: 120 vac and 24vdc in same conduit [Re: shop_test]  
BullDog  Offline
Member
Joined: May 2009
Posts: 20
Great Lakes Region
Sorting out when it's Ok and when it isn't seems an interesting subject.

Can you provide a few more project details that describe the application?

Thanks


#187255 - 06/18/09 12:42 PM Re: 120 vac and 24vdc in same conduit [Re: BullDog]  
shop_test  Offline
Member
Joined: Aug 2008
Posts: 10
California
A rigid coduit connects a control panel with a metering device.
The device uses 120VAC for control power and has a contact that will have 24vdc going through it and used back at the control panel as an input to a PLC.


#187256 - 06/18/09 12:56 PM Re: 120 vac and 24vdc in same conduit [Re: shop_test]  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
Since these circuits are functionally related, even if the 24 vdc is class 2 or class 3, you could take advantage of exception #2 to 725.130(A) and also apply 725.48(B)(1) and run the 24 vdc as a class 1 circuit.


Few things are harder to put up with than the annoyance of a good example.

#187261 - 06/18/09 02:28 PM Re: 120 vac and 24vdc in same conduit [Re: Tom]  
BullDog  Offline
Member
Joined: May 2009
Posts: 20
Great Lakes Region
Shop_Test - As I understand it the two could in certain applications be serving the same device and be combined, but the NEC calls out certain separation devices and or distance that must be maintained between the conductors?

Tom- In the case of wiring as a Class 1 circuit (upgrade the wiring), NEC2005 725.27(A) would require 18 or 16 AWG and 725.27(B) would require 600 volt rated insulation of specific types?

Am I barking up the right tree?


#187266 - 06/18/09 02:53 PM Re: 120 vac and 24vdc in same conduit [Re: BullDog]  
JValdes  Offline
Member
Joined: Jun 2007
Posts: 301
South Carolina
Same temperature rating, your good. Personally, I always separate power from control. Regardless of the situation. Just my way.


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