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BUILDING WIRES TYPES AND APPLICATION GUIDE

BUILDING WIRES TYPES AND APPLICATION GUIDE
What are the common types of wires used for building wiring installation?

TW (Thermoplastic Moisture-Resistant)
The TW conductors are solid or stranded annealed (soft) copper, insulated with a moisture resistant and flame retardant polyvinyl compound (PVC). TW wire is used in interior wiring at circuit voltages up to 600 volts. Maximum operating temperature is 60°C in dry or wet application. Type TW building wire is used in residential, commercial and industrial buildings for generalpurpose lighting, appliance, power, control and relay panel applications. It is used for low ampacity rated circuits. This type of wire may be installed in conduits, ducts or raceways. Type TW wire is also suitable for installations in ambient temperatures down to -10°C.

THW (Thermoplastic Heat and Moisture Resistant)
The THW conductors are solid or stranded annealed (soft) copper, insulated with a tough heat and moisture resistant, and flame retardant polyvinyl compound (PVC). It is used in interior wiring at circuit voltages up to 600 volts. Maximum operating temperature is 75°C in dry or wet application. It can be used for general-purpose lighting, appliance, power, control and relay panel applications. It is also applicable as machine tool wire and appliance wiring material. It is used for medium ampacity rated circuits. This type of wire may be installed in conduits, ducts or raceways.

THHN/THWN (Thermoplastic Heat and Moisture Resistant Wire with Nylon Jacket)
The THHN/THWN conductors are solid or stranded annealed (soft) copper, insulated with a tough heat and moisture resistant, and flame retardant polyvinyl compound (PVC) with oil, chemical, and abrasion resistant nylon (polyamide) jacket. It is used in interior wiring at circuit voltages up to 600 volts. Maximum operating temperature is 90°C for dry applications (THHN) and 75°C for wet applications (THWN). It can be used for general-purpose lighting, power, control and relay panel applications. It is also applicable for machine tool wire and appliance wiring material. It is used for high ampacity rated circuits. This type of wire may be installed in conduits, ducts or raceways.

source: 2010 IIEE Technical Manual

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