TW

Flame-retardant, moisture-resistant thermoplastic insulation. Rated 60°C wet or dry.

THHN

Flame-retardant and heat-resistant thermoplastic insulation with a jacket of extruded nylon. Rated 90°C dry only.

THW

Flame-retardant, moisture- and heat-resistant thermoplastic insulation. Rated 75°C wet or dry.

THW-2

Same as THW, except the wire is rated 90°C wet or dry.

THHW

Flame-retardant, moisture- and heat-resistant thermoplastic insulation. Rated 90°C dry and 75°C wet.

THWN

Flame-retardant, moisture- and heat-resistant thermoplastic insulation with a jacket of extruded nylon. Rated 75°C wet or dry.

THWN-2

Same as THWN, except the wire is rated 90°C wet or dry.