Solar current transformers, Class 1?

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Todd0x1

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How would one categorize (not sure if thats the right term) the output of the current transformers used in Solar? The only thing I can find in enphase documentation is that theyre not class 2 and do not use class 2 wiring methods.

These are not the typical 0-5A CTs that are used for instrumentation and such. The ones from Enphase have a sticker that says 200A 0.5v. The instructions say if the leads are extended they should be twisted. The contractor in question has been using twisted 18ga 600v UL1015 MTW, same as the factory wires on the CTs. There has been a couple times where an inspector has rejected use of that wire, but allowed THWN to replace it. I believe this is because of it not having a NEC wire type printed on it besides MTW. I believe I have a solution with TFFN which is specifically listed as one of the acceptable wire types in 18ga for class 1, but I need to make sure I've got this right.
 
Todd0x1 said:
How would one categorize (not sure if thats the right term) the output of the current transformers used in Solar? The only thing I can find in enphase documentation is that theyre not class 2 and do not use class 2 wiring methods.
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Where do they say that? Previous Enphase tech briefs directed extending Consumption CTs using CL3R (not in the same conduit as power) which is a Class2/3 wiring method. Have they changed their minds?

As far as I know the code and standards are silent on the basic question of classification, and I've looked into it a bit. I mostly treat them as Class 1 because I often want to run them with circuit conductors.

These are not the typical 0-5A CTs that are used for instrumentation and such. The ones from Enphase have a sticker that says 200A 0.5v. The instructions say if the leads are extended they should be twisted. The contractor in question has been using twisted 18ga 600v UL1015 MTW, same as the factory wires on the CTs. There has been a couple times where an inspector has rejected use of that wire, but allowed THWN to replace it. I believe this is because of it not having a NEC wire type printed on it besides MTW. I believe I have a solution with TFFN which is specifically listed as one of the acceptable wire types in 18ga for class 1, but I need to make sure I've got this right.
Click to expand...

I've cone to the same conclusion about TFFN. It should be permitted if run only with 'functionally associated' circuits, e.g. the feeder to the combiner or the the System Controller. It's permitted to use Class 1 methods for a Class 2 or 3 circuit in any case. See discussion with code citations here.

0-10 inside the same conduit

Hi, I understand that class 1 and class 2 wiring cannot be installed in the same raceway without a barrier but I'm wondering if I were to use #12 AWG THHN for both the high voltage (120V) and the 0-10 dimming controls if that would be code sufficient? I don't see why not but that's why I'm here
forums.mikeholt.com

FWIW, although not twisting the leads might reduce accuracy I haven't really found it to matter.
 
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