Q Jim, N2CAU, asks, “In wire antenna construction articles I often run into references such as ‘THHN stranded copper wire.’ What does THHN mean?
A THHN is one of many National Electrical Code conductor type designations. Specifically, THHN is the designation for PVC insulated, nylon-jacketed conductor for use in dry locations. Alternatively, THWN stands for a PVC insulated, nylon-jacketed conductor for use in wet or dry locations.
Some other NEC designators you may encounter include:
USE—underground service entrance cable
TC—power and control tray cable
TFN—PVC insulated, nylon-jacketed conductors in sizes no. 18 and no. 16 AWG for use in dry locations.
RTA—Thermoplastic insulated, aluminum shielded, polyethylene jacketed communication cable.
From QST September 1999
