Single-Core Copper Building Wire, THHN/THWN

Overview

What this wire is

This is a single-core copper building wire with a PVC insulation layer. It is the kind of conductor electricians pull through conduit for lighting circuits, sockets, sub-mains and panel wiring. We make it in the THHN, THWN and THWN-2 designations, so you can match the marking your local market and inspectors expect.

Why the type matters

The three designations are not interchangeable labels. They describe different insulation constructions and different conditions of use, for example dry or wet locations. Choose the designation your project or your customers call for, and check that the rated voltage and construction suit the installation.

Conductor sizes

There is no fixed list of sizes. The gauges or cross-sections, in AWG or mm², and the quantity of each define the schedule, and the wire is made to it. This works well for distributors who need a mix of sizes and for contractors with a bill of quantities.

Where it is used

Typical jobs are new residential blocks, shop fit-outs, small factories and electrical contractor stock. It is not an armoured or direct-burial cable; for underground runs, see our armoured power cable.

Options

Wire type (THHN, THWN or THWN-2), conductor sizes, colors, coil or reel length, and marking on the jacket can be specified. A packing plan for container loading goes with the offer.

Packing and documents

Coils are wrapped and strapped so they survive handling at the port. We list wire type, size and length on each pack label, so your warehouse team can sort the container quickly on arrival.

THHN, THWN and THWN-2: which one to order

The letters describe what the wire can tolerate. THHN is rated 90 °C in dry locations. THWN adds a 75 °C wet rating, so it can run in damp conduit. THWN-2 carries 90 °C in both wet and dry locations, which is why most buyers now order it as the default when markets allow. All three have a thin nylon layer over the PVC, which makes the wire slide through conduit more easily and resists abrasion and oil.

Next to our BV wire, THHN is a stranded AWG-sized wire for conduit systems, rather than a metric solid wire; this is the standard in many American-influenced markets. Next to the armoured cable, it has no steel armour and is not meant for direct burial; it goes inside a conduit. Because stranded wire is flexible, it suits panel wiring, motor leads and long conduit pulls. Contractors usually order a handful of sizes in several colors, packed in coils for conduit work and in reels for large runs. For ampacity, follow the table of your local code and the temperature rating of your terminals.