XHHW-2 vs THHN-2/THWN-2

[theoldwizard1]

I understand the difference is in insulation. XHHW-W use cross-linked polyethylene and THHN-2/THWN-2 uses PVC with a Nylon coating, but what condition would make you chose on over the other ? THHN-2/THWN-2 is a bit cheaper.

 

[manwithtools]

Link to a good explanation: https://www.kristechwire.com/why-should-electrical-contractors-use-xhhw/

 

[dscheidt]

XHHW has higher breakdown voltage (most or all of it is dual rated at 600/1000 V), and lower leakage. It has higher opererating temperatures (THHN gets britttle in cold). XHHW is more abrasion resistant, and is resistant to different chemicals.

 

[Two Sheds]

XHHW-2 is available in larger gauges in aluminum for feeder use. I used it in 2 AWG for the feeder to my garage. An advantage of it is that it is rated for both indoor and outdoor use, so I could continue the conduit inside. For branch circuits in conduit, I used THWN-2 copper, which is the most commonly used wire for that purpose.

 

[MatBirch]

XHHW is all I was ever allowed to install for Arctic applications...