What Is The Difference Between THHN Vs THWN Wire?

THHN wire stands for Thermoplastic High Heat-resistant Nylon-coated wire, whereas THWN wire stands for Thermoplastic Heat and Water-resistant Nylon-coated wire. The main difference between the two lies in the "W" in THWN. This stands for "water-resistant", meaning that THWN wire is suitable for use in wet or damp locations.

Both THHN and THWN wires have a PVC insulation covering, but the nylon coating provides extra protection against heat and moisture. THHN wire is best suited for use indoors, in dry locations, or where exposure to water is minimal. It can handle temperatures up to 90°C, making it ideal for use in circuits that generate low to medium levels of heat. THWN wire, on the other hand, can handle temperatures up to 75°C and is suitable for use in wet locations or outdoor installations.

Another difference between the two is their intended use. THHN wire is primarily used for commercial and industrial applications, such as in conduit wiring for motors, lighting fixtures, and control circuits. THWN wire, however, is commonly used in residential wiring applications, especially in areas prone to moisture, such as bathrooms, kitchens, and outdoor installations.

When selecting between THHN vs THWN wire, it's important to consider the intended application, as well as the environmental factors that the wire will be exposed to. Both wires are produced in a wide range of sizes and colors to help facilitate easier identification and installation. It's also important to confirm that the wire you are planning to use meets UL (Underwriters Laboratories) safety standards.