UL 83 Cable

UL 83 covers 600-volt thermoplastic-insulated wires and cables. Key types certified under this standard include:

• Building Wires: THHN, THWN, THWN-2, TW, THW, and equivalent variants such as T90 Nylon and TWN75.

• Flexible Service Cords: Portable power cords such as TSJ and TSJ-N.

• Specialty Conductors: Water-resistant submersible pump cables.

• Multiconductor Core Wires: Insulated single conductors used as internal cores for Type MC (Metal-Clad) and Type TC (Tray) cables.

The primary distinction is the insulation material and its thermal/mechanical properties:

• UL 83 (Thermoplastic): Uses PVC insulation, often extruded with a nylon outer jacket (e.g., THHN/THWN). Thermoplastic compounds can re-soften at extreme heat and stiffen in cold temperatures. Ratings are capped at 600V.

• UL 44 (Thermoset): Uses cross-linked polyethylene (XLPE) or rubber compounds (e.g., XHHW, XHHW-2, RHH, RHW). Thermoset insulation undergoes a chemical cross-linking process that prevents it from melting under high temperatures, offering superior chemical resistance, lower moisture absorption, and ratings up to 2000V.

Yes, but only specific UL 83 cable types designated for wet environments.

• Approved Types: Wires with a “W” designation—such as THWN, THWN-2, THW, and TW—are explicitly rated for wet conduit installations and moisture exposure. Most modern building wire is dual-rated as THHN/THWN-2, allowing it to be used in both dry (90°C) and wet (90°C) environments.

• Non-Approved Types: Standard THHN lacking a dual “W” rating is restricted to dry or damp locations only.