Sep. 13, 2017
THHN uses a thinner PVC insulation. This thinner insulation—while saving
space—could be a disadvantage depending on the application. The reduced coating
can lead to current leakage and can break down from chemical or environmental
XHHW-2 aluminum conductor has XLPE insulation instead of the PVC insulation
used in THHN wire.
This makes XHHW the more expensive option, but its coating is more resistant
to chemicals, ozone and abrasions. THHN’s coating is thinner and emits a toxic
smoke when burned. This is avoided in XHHW-2 with the use of a different
THHN wire isn’t as flexible as some alternatives because of the nylon
coating—what you gain in mechanical strength and sturdiness, you lose in
flexibility. XHHW-2 aluminum conductor’s coating is more flexible and may be
advantageous for difficult projects.