THWN in parallel with XHHW

[malachi constant]

Have a 480V 1000A service entrance feeder where one conduit (and associated conductors) was damaged. We are considering pulling XHHW in to replace the THWN. Is there an issue having two conduits filled with THWN and the third with XHHW? All sizes would be the same.

 

[iwire]

No you cannot mix insulltion types like that

310.10(H)(2) Conductor Characteristics. The paralleled conductors
in each phase, polarity, neutral, grounded circuit conductor,
equipment grounding conductor, or equipment bonding
jumper shall comply with all of the following:

(1) Be the same length

(2) Consist of the same conductor material

(3) Be the same size in circular mil area

(4) Have the same insulation type

(5) Be terminated in the same manner

 

[ActionDave]

Short answer is no you can't do that. You could use the two different insulation types but they have to be the same for each phase.

 

[iwire]

Short answer is no you can't do that. You could use the two different insulation types but they have to be the same for each phase.

I agree, phase A could be XHHW with B & C THHN.

 

[ActionDave]

I agree, phase A could be XHHW with B & C THHN.

Your so cute when your agreeable. Buy you a beer?

 

[malachi constant]

Looks like the question is provide THWN in the one or repull XHHN in all. Have some thinking to do. Thanks!!