Popular Wire Designation and What They Mean

MTW
Machine Tool Wire (UL)

RHH/RHW
Rubber insulated High Heat/Water Resistant insulated wire (UL)

TFFN
Thermoplastic Flexible Fixture wire Nylon jacketed (UL)

TFN
Thermoplastic Fixture Wire Nylon jacketed (UL)

THHN
Thermoplastic High Heat resistant Nylon jacketed insulated wire (UL)

THWN
Thermoplastic Heat and Water resistant insulated wire, Nylon jacketed (UL)

TWN
Thermoplastic Water resistant insulated wire, Nylon jacketed (CSA)

USE
Underground Service Entrance cable

XHHW
Cross-linked High Heat Water resistant insulated wire (UL)

Q: We are familiar with CSA, what is C-UL?
A: CSA (Canadian Standards Association) and C-UL are standards making bodies that can list products for use in the Canadian market. C-UL is controlled by Underwriters' Laboratories.

Q: What is FT1 and can FT1 replace FT2?
A: FT1 is a Canadian Vertical Flame Test and can be used to replace FT2 anytime. FT2 is a horizontal burn flame test which is much easier to pass.

Cerrowire's 14 AWG - 1 AWG THHN/TWHN passes the UL VW-1 flame test and Cerrowire's 1/0 AWG - 750 MCM passes the UL vertical flame test. Both of these tests can replace either the FT-1 or FT-2. Cerrowire's XHHW passes the FT-2 horizontal flame test.

Q: Are your standard stock items that meet the requirements of ASTM B-3 and ASTM B-8 all soft-drawn?
A: All items in our stock are soft-drawn.