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120 vac and 24vdc in same conduit
#187186
06/16/09 08:07 PM
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Joined: Aug 2008
Posts: 10
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I cant find this in the NEC. Is there a reference in the NEC to separate 24vdc and 120 vac into their own conduits?
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Re: 120 vac and 24vdc in same conduit
[Re: shop_test]
#187197
06/17/09 12:13 AM
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Joined: Mar 2003
Posts: 849
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Try Article 725. 2005 NEC 725.26 725.41 725.55 Depending on the class of the 24volt.
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Re: 120 vac and 24vdc in same conduit
[Re: Yoopersup]
#187206
06/17/09 03:24 PM
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Joined: Aug 2008
Posts: 10
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Thanks for the quick feedback. Unfortunately I only have the 2008 NEC and 725.26 / 725.55 are no longer listed.
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Re: 120 vac and 24vdc in same conduit
[Re: shop_test]
#187222
06/17/09 07:11 PM
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Joined: Mar 2003
Posts: 849
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2008 NEC Article 725 725.48 725.136 Try thoses Also read Article 725 Definitions for Classes 1,2,3.
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Re: 120 vac and 24vdc in same conduit
[Re: Yoopersup]
#187226
06/17/09 08:07 PM
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Joined: Aug 2008
Posts: 10
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Member
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Thanks. It looks like the answer is yes it is acceptable for our situation.
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Re: 120 vac and 24vdc in same conduit
[Re: shop_test]
#187254
06/18/09 12:30 PM
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Joined: May 2009
Posts: 20
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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
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Re: 120 vac and 24vdc in same conduit
[Re: BullDog]
#187255
06/18/09 12:42 PM
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Joined: Aug 2008
Posts: 10
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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.
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Re: 120 vac and 24vdc in same conduit
[Re: shop_test]
#187256
06/18/09 12:56 PM
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Joined: Jan 2001
Posts: 1,044
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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.
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Re: 120 vac and 24vdc in same conduit
[Re: Tom]
#187261
06/18/09 02:28 PM
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Joined: May 2009
Posts: 20
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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?
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Re: 120 vac and 24vdc in same conduit
[Re: BullDog]
#187266
06/18/09 02:53 PM
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Joined: Jun 2007
Posts: 301
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Same temperature rating, your good. Personally, I always separate power from control. Regardless of the situation. Just my way.
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