Building Wire


Q: What is TEWN?
A: TEWN is a Canadian General Purpose Wire, the Canadian equivalent of TFFN.

Q: Why can't TFN be also dual-rated as MTW?
A: Because the stranding is too coarse. TFFN which is more flexible can be dual rated.

Q: Does Cerrowire make a VW-1 version of TFFN?
A: No, it is not a popular item and the costs would be prohibitive.

THHN, THWN, MTW, T90 Nylon and TWN 75 is VW-1 rated in sizes 14 AWG through 1 AWG

Q: Is the nylon jacket on THHN for mechanical protection only?
A: No, it also serves as a barrier to the effects of gasoline and oil.

Q: Can the words "Cable Tray Use" be applied to all sizes of THHN type products?
A: No, only sizes1/0 AWG and larger are allowed in trays per the NEC provided they pass the UL 1581vertical tray flame test or the CSA FT4 flame test.


Q: What would be the CSA equivalent product to XHHW-2?
A: Cerrowire's XHHW-2 is marked "RW90".
Q: Can XHHW-2 be made with a 2000 Volt rating?
A: No, for 2000 Volt you would purchase an RHW-2 wire instead.

Q: Why purchase a thermoset insulated XHHW when you can buy a thermoplastic insulated product having the same rating ?
A: The main reasons are: 1) the thermoset product has better low temperature properties and 2) a higher K Value (electrical properties, 10,000 K Value vs. 4000). The short circuit current carrying capacity is also greater, providing greater protection from meltdown than THHN.

Q: Can XHHW-2 be rated gasoline and oil resistant?
A: Yes.

Q: Does XHHW-2 have to meet any flame test requirements?
A: As a minimum, it would have to pass a horizontal burn test or FT-2 flame test.

Q: Can XHHW-2 be rated for use in cable trays?
A: Sizes 1/0 and larger can be rated when marked for “CT Use” or “For use in Cable Trays”. Cerrowire’s 1/0 and larger XHHW-2 is marked “For CT Use”.

Q: Can XHHW-2 be rated for Sunlight Resistance?
A: Yes, Black XHHW-2 Conductors sizes 8 AWG and larger are marked "Sunlight Resistant."

Bare Copper/SE Style U

Q: Why is the base color of both inners of SE Style U colored black?
A: Both the PVC insulation and the nylon jacket on the inners now have to pass a 300 hour weather meter test, and black best meets the requirement.