Electrical Wire

NM-B (Non-Metallic sheathed cable, Type B) forms the backbone of residential electrical systems. This cable features insulated conductors in a non-metallic sheath for dry interior locations up to 90°C (194°F), with a bare copper grounding conductor meeting NEC three-wire system requirements.

Primary applications include interior wall installations, branch circuits for lighting and outlets, and feeder circuits up to 600 volts.

THHN/THWN-2 wires serve industrial applications with PVC insulation and nylon jacket, operating at 90°C dry and 75°C wet. These single conductors require conduit protection but offer superior heat dissipation and easier installation in complex runs.

Key specifications: 600V rating, UL 83 insulation standards, available in solid and stranded configurations.

UF-B cable resists moisture, soil chemicals, and physical damage through solid thermoplastic insulation. Direct burial eliminates conduit needs at 24-inch depth for 120V circuits, with sunlight-resistant jacket allowing wet location above-ground use.

MC cable provides aluminum or steel armor protection with EMI shielding. Required for commercial installations, exposed locations, and fire-resistant applications, the armor serves as equipment grounding path.

Temperature ratings establish maximum conductor operating temperature, affecting ampacity calculations. Standard wire features 75°C or 90°C ratings. Voltage ratings must exceed circuit voltage—most residential wire carries 600V ratings for 120V and 240V systems.

Ambient temperatures above 86°F require ampacity reduction, and conductor bundling beyond three current-carrying wires necessitates derating.