CTs - Conduit fill factor

[msi99]

Are we allowed to use the CTs in the same conduit as the AC wires from the Inverter to the main panel without having the upsize the conduit size. Or should those be considered for conduit fill factor and Table C calculation
Ex: If a 3/4the inch EMT has (2) #6, (1) #6 EGC and (1) Neutral, would be be able to add 2 sets of twisted pair CTS in the same 3/4-inch conduit per code?

 

[don_resqcapt19]

All conductors and cables that are physically in the conduit are counted for fill. You would have to find the area of the twisted pair cables and add that to the area of the 6 AWG conductors to find out if you are exceeding the 40% maximum permitted fill.
Another issue would be what type of circuit is the CT circuit? Depending on the type of CT it could be a Class 2 circuit and not even be permitted in the same raceway.

 

[jaggedben]

...
Another issue would be what type of circuit is the CT circuit? Depending on the type of CT it could be a Class 2 circuit and not even be permitted in the same raceway.

I have always wondered how to classify CT circuits and have never found a good answer in the code. They certainly do not obviously fit any of the categories in 725.121(A). So I have always treated them as Class 1 circuits and run them in raceways with circuits for functionally associated equipment as allowed by 725.48(B)(1).

No disagreement on the conduit fill question.

 

[don_resqcapt19]

I have always wondered how to classify CT circuits and have never found a good answer in the code. They certainly do not obviously fit any of the categories in 725.121(A). So I have always treated them as Class 1 circuits and run them in raceways with circuits for functionally associated equipment as allowed by 725.48(B)(1).

No disagreement on the conduit fill question.

If they are the traditional CTs with 0-5 amp output, I would see them as a Class 1 circuit, but if they provide a milliamp output I would probably be thinking of a Class 2 circuit.

 

[jaggedben]

If they are the traditional CTs with 0-5 amp output, I would see them as a Class 1 circuit, but if they provide a milliamp output I would probably be thinking of a Class 2 circuit.

Sorry, what's that based on?

 

[don_resqcapt19]

Sorry, what's that based on?

Because the 0-5 amp outputs would not fall into the current limits for Class 2 or 3 circuits, and the milliamp output would likely fall into the Class 2 limits.
This is just how I see them and how I have have seen them treated on engineered industrial projects, but there is no specific language in the NEC.

 

[jaggedben]

Thanks. So do I have it correct that these limits Class 2 and Class 3 limits are in product standards but are not in the code?

 

[don_resqcapt19]

Thanks. So do I have it correct that these limits Class 2 and Class 3 limits are in product standards but are not in the code?

Chapter 9, Tables 11(A) and 11(B).

 

[msi99]

All conductors and cables that are physically in the conduit are counted for fill. You would have to find the area of the twisted pair cables and add that to the area of the 6 AWG conductors to find out if you are exceeding the 40% maximum permitted fill.
Another issue would be what type of circuit is the CT circuit? Depending on the type of CT it could be a Class 2 circuit and not even be permitted in the same raceway.

All conductors and cables that are physically in the conduit are counted for fill. You would have to find the area of the twisted pair cables and add that to the area of the 6 AWG conductors to find out if you are exceeding the 40% maximum permitted fill.
Another issue would be what type of circuit is the CT circuit? Depending on the type of CT it could be a Class 2 circuit and not even be permitted in the same raceway.

Class 2 CT cannot be installed in the same raceway due to the PV circuit exceeding 150V?

 

[jaggedben]

Class 2 CT cannot be installed in the same raceway due to the PV circuit exceeding 150V?

No. Where are you getting 150V?

Your original question was about putting the CT leads in the same conduit as the AC inverter output. That is generally fine, so long as the CT leads are Class 1 or better and all conductors in the conduit are rated for the highest voltage.

CT leads would not be allowed with PV source and output circuits (i.e. 'raw' DC from solar panels) but I don't think that's your question, and it is also true regardless of voltage.

 

[msi99]

Could you please explain which code reference allows for the use of shielded CT cables (specifically CAT 6) and the power circuits (AC side of the PV) to be in the same raceway/conduit when the wires are insulated for the highest conductor voltage? According to Article 725.136(A), the control, signal, and communication wiring must be segregated from power and lighting circuits.

 

[jaggedben]

No one said anything about Cat6 so far and I'm quite doubtful that could be compliant.

However, in the 2020 NEC see 725.130(A) Exception #2 (and Informational Note) as well as 725.48(B)(1) and 725.46 thru 49 in general. There are usually other ways to extend CT leads. The wiring method matters.

CT leads may or may not be Class 2 circuits depending on details alluded to above. The ones I use I'm able to treat as Class 1 circuits.