Benefits of XHHW conductors versus THHN???
Benefits of XHHW conductors versus THHN???
(OP)
I know XHHW type conductors provide higher short circuit ratings and have overall better thermal characteristics than THHN conductors. What other advantages are there?






RE: Benefits of XHHW conductors versus THHN???
RE: Benefits of XHHW conductors versus THHN???
As far as the outer nylon jacket of THHN or THWN, it is just that, a jacket and is not part of the insulation system. When UL tests the insulating properties of these types of conductors the jacket is removed. Damage to the jacket is not a problem but damage to the PVC insulation under the jacket is. The jacket serves two purposes, one, to protect the insulation, and two, to low the friction when the conductors are installed into raceways.
Don
RE: Benefits of XHHW conductors versus THHN???
THHN is slicker than the XLPE insulation used in XHHW so it pulls easier.
Note that using the 90C ampacity rating allows derating for multiple conductors in a conduit or high ambient temperatures without having to increse the wire size. With THHN you have to start the derating calculation at the 75C ampacity.
RE: Benefits of XHHW conductors versus THHN???
RE: Benefits of XHHW conductors versus THHN???
THHN can be derated starting at the 90C ampacity, as can THWN-2 and XHHW-2. THWN and XHHW would have to be derated starting at the 75C ampacity. If the application is dry location only, only the THHN rating applies, the THWN or THWN-2 label is irrelevant.
RE: Benefits of XHHW conductors versus THHN???
FWIW, we typically allow THWN/THHN for smaller lighting and receptacles circuits and specify XHHW for sizes larger than #10 AWG.
Just my $0.02