24vdc/120vac

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Hunter J

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What section of the NEC deals with 24VDC and 120VAC when is comes to the two being in the same conduit or if it is even allowed?
The application is I/O for automation and the conduit/pipe is from enclosure to enclosure.

Thanks
 
Hunter J said:
What section of the NEC deals with 24VDC and 120VAC when is comes to the two being in the same conduit or if it is even allowed?
The application is I/O for automation and the conduit/pipe is from enclosure to enclosure.

Thanks
Click to expand...

300.3(C)(1) 600 Volts, Nominal, of Less
 
In the same conduit it's not allowed if the 24 volts is from a class 2 or 3 circuit, 725.136.
 
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cadpoint,
I knew there was a online NEC but now it appears you have to resister so I can't read that right now.
So if the circuits are 600V and less and the insulation is rated accordingly then you can run 24VDC control and 120VAC control circuits in the same pipe also assuming you follow the fill capacity of the pipe?

Thanks for your time.
 
Hunter J said:
I knew there was a online NEC but now it appears you have to resister so I can't read that right now.
Click to expand...

cadpoint:

300.3(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less. 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.
Exception: For solar photovoltaic systems in accordance with 690.4(B).
FPN: See 725.136(A) for Class 2 and Class 3 circuit conductors.
Click to expand...
infinity:

725.136 Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband Communications Cables.
(A) General. Cables and conductors of Class 2 and Class 3 circuits shall not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, non?power-limited fire alarm circuits, and medium-power network-powered broadband communications circuits unless permitted by 725.136(B) through (I).
(B) Separated by Barriers. Class 2 and Class 3 circuits shall be permitted to be installed together with the conductors of electric light, power, Class 1, non?power-limited fire alarm and medium power network-powered broadband communications circuits where they are separated by a barrier.
(C) Raceways Within Enclosures. In enclosures, Class 2 and Class 3 circuits shall be permitted to be installed in a raceway to separate them from Class 1, non?power-limited fire alarm and medium-power network-powered broadband communications circuits.
(D) Associated Systems Within Enclosures. Class 2 and Class 3 circuit conductors in compartments, enclosures, device boxes, outlet boxes, or similar fittings shall be permitted to be installed with electric light, power, Class 1, non?power-limited fire alarm, and medium-power network-powered broadband communications circuits where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits, and where (1) or (2) applies:
(1) The electric light, power, Class 1, non?power-limited fire alarm, and medium-power network-powered broadband communications circuit conductors are routed to maintain a minimum of 6 mm (0.25 in.) separation from the conductors and cables of Class 2 and Class 3 circuits.
(2) The circuit conductors operate at 150 volts or less to ground and also comply with one of the following:
a. The Class 2 and Class 3 circuits are installed using Type CL3, CL3R, or CL3P or permitted substitute cables, provided these Class 3 cable conductors extending beyond the jacket are separated by a minimum of 6 mm (0.25 in.) or by a nonconductive sleeve or nonconductive barrier from all other conductors.
b. The Class 2 and Class 3 circuit conductors are installed as a Class 1 circuit in accordance with 725.41.
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RE: 24v and 120v in same raceway

RE: 24v and 120v in same raceway

Cadpoint,
I read 300.3(C)(1) 600 Volts, Nominal, of Less. It says it IS permitted, provided all conductors have insulation rating of the highest voltage.

Infinity,
I have 2008 NEC - I read 725.127 Wiring Methods on Supply Side of the Class 2 or Class 3 Power Source.
Please help myself and OP Hunter_J understand why it is NOT permitted. (Elaborate)

Thanks a bunch for your time
 
Now I am really confused?

Now I am really confused?

725.136 Non?Power-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband Communications Cables.

I don't think this is applicable?

24vdc I/O is neither Non?Power-Limited Fire Alarm Circuit Conductors or Medium-Power Network-Powered Broadband Communications Cables.
 
IMM_Doctor said:
725.136 Non–Power-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband Communications Cables.

I don't think this is applicable?
Click to expand...

Sorry, quoted the wrong article, but now that I see 725.127 I am also confused. But here it is just the same.

725.127 Wiring Methods on Supply Side of the Class 2 or Class 3 Power Source.
Conductors and equipment on the supply side of the power source shall be installed in accordance with the appropriate requirements of Chapters 1 through 4. Transformers or other devices supplied from electric light or power circuits shall be protected by an overcurrent device rated not over 20 amperes.
Exception: The input leads of a transformer or other power source supplying Class 2 and Class 3 circuits shall be permitted to be smaller than 14 AWG, but not smaller than 18 AWG if they are not over 12 in. (305 mm) long and if they have insulation that complies with 725.49(B).
Click to expand...
 
IMM_Doctor said:
725.136 Non?Power-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband Communications Cables.

I don't think this is applicable?

24vdc I/O is neither Non?Power-Limited Fire Alarm Circuit Conductors or Medium-Power Network-Powered Broadband Communications Cables.
Click to expand...

725.136 says "separation from" included on the list is light and power conductors.
 
I am not sure from the OP if this is line side supply or load side.

300.3(C)
Permits conductors of different systems in the same raceway as long as the insulation types and ratings are correct.


BUT....
Take a look at the FPN
"See 725.55(A) for Class 2 and Class 3 circuit conductors."

If the 24V conductors are supplied from a Class2 or 3 supply, the 24V conductors will not be permitted in the same raceway as the power conductors reqardless of the insulation types.
 
How do Generac generators get away with having the 12v control and 240v sense wires in the same 4-conductor bundle?
 
don_resqcapt19 said:
That could be a Class 1 control circuit and would be permitted in with directly associated power conductors.
Click to expand...


Manufacturers can install wiring differently within their equipment than we do in the field. They have it tested as such and sell it as a "manufactured assembly".

We are not permitted to do so in the field, as there is no field testing and too many variables for control of that portion of the field installation.
 
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