Article 725

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electric1

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We are installing numerous pressure reducing pilot valves on a project. These valves require a 24 VDC (DO) power supply (2-#14 THWN) and a (AO) #18 TSP cable for control.

How do you determine from the code if it is legal to install the conductors (digital output)and the cable (analog output) in the same raceway / conduit?
 
Re: Article 725

Check 725.56(D)(1) which referes you to 800.xxx.

Read through 800 to be sure this is the right type of TSP and circuits.

It seems as though you are allowed to do this if I am guessing correctly about your system.
 
Re: Article 725

It depends on the class of the circuit. Art 725 has three type limited energy circuits, Class 1, 2 and 3. The class is determined by the power supply, for example most plug in wall warts are class 2 power supplies. Your 24 v systems are most likely class 2, but they could be class 1 power limited. Class 2 and 3 can run in the same enclosure or raceway, class 1 can't run with class 2 or 3. For your application look at the type fusing used on the power supply, you need to determine the volt amps.
 
Re: Article 725

Why does nominal 24VDC have to be installed using an Art725 wiring method? Isn't Art 725 optional?

I know there are advantages if the circuits are Class 2 or 3, but what if I don't like the limitation imposed by using a 4A maximum 24VDC power supply?
 
Re: Article 725

Tom, Art 411 is for low voltage lighting circuits.

For industrial control circuits operating at 24VDC nominal, it looks like I need to follow Art 725 or else the minimum wire size is #12AWG per Art 720.
 
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