Sub panel wiring

[blueheels2]

So I’ve got a 200 amp sub panel that I’m feeding off a meter main. I used xhhw AL for the 2 hots and neutral. I used #6 thhn as the ground wire. I feel like this is a violation but I can’t find the reference. Anyone have a reference. My brain keeps saying something like conductors of ther same type and insulation but I think that relates to Class 2 running with power.

TIA

 

[blueheels2]

Looking around it appears as long as they have the same voltage rating I’m good?

 

[Dsg319]

I can’t think of anything prohibiting it as long as there grouped together and/or in the same raceway.

 

[goldstar]

I’m away on vacation so I don’t have a Code book with me. My thinking is that the ground wire has to be sized in accordance with the size of the service or feeder. Since it’s a sub panel I would think the EGC should be #4 THHN. There used to be a chart in the 310 section somewhere but I think it’s been moved.

 

[infinity]

There is no requirement for the insulation type to be the same. Unless the feeder conductors have been up-sized the #6 EGC is correct for 200 amps.

 

[Carultch]

My brain keeps saying something like conductors of ther same type and insulation but I think that relates to Class 2 running with power.

You might be thinking of parallel conductors, where they have to be as identical as possible within a given part of the circuit (phase, polarity, neutral, egc). The conductor metal, the insulation, the size, the length, and the conditions of installation, all have to be identical to prevent any one conductor in a parallel group from becoming a preferred path over its partners, and not dividing the current equally.

It's OK to mix different types of wires for circuits in general, as long as everything is sized appropriately, and has the necessary ratings that apply. In most applications I'm familiar with, XHHW-2 can be substituted for THWN-2 without issue, but not necessarily vice-versa, since XHHW-2 has a few subtle advantages over its THWN-2 counterpart. As long as you aren't depending on one of those advantages, the two types are interchangeable.