thhn wire, thwn wire, thwn 2 wire are American standard wires with two types of conductor structures: thhn solid wire and strained wire thhn, both of which are within the scope of UL83 certification. They all belong to heat-resistant nylon sheathed wires, which are single core wires with PVC insulation and nylon sheath. Usually used in electrical conduits for buildings. Their basic structure and purpose are similar, but the "W" in their names represents waterproofing, which directly affects their performance characteristics. Its heat resistance and oil resistance make cable thhn, thwn cable, thwn 2 wire suitable for electrical appliances, machine tools, and buildings. Their letter symbols represent different meanings, including the type of material, specifications, and voltage levels. Below we will provide a detailed explanation of their direct differences.
thhn electrical wire cannot be used in damp environments anymore, it can only be used in dry environments, and the operating temperature is 90 degrees. Thwn wire can be used in both dry and humid environments, with a usage temperature of 90 degrees Celsius in dry environments and 75 degrees Celsius in humid environments. The performance of Thwn 2 wire is better than the previous two types. Like wire type Thwn, Thwn 2 wire can be used in both dry and humid environments, with the only difference being that the temperature level is 90 degrees in both environments.
In summary, thwn cables are more suitable for use in humid or harsh environmental conditions due to their higher heat resistance and waterproof performance, while THHN cables are more suitable for use in dry environments. That is to say, thwn 2 wire can replace thwn wire or thhn wire. thwn wire can replace thhn wire, but thhn wire cannot replace either thwn wire or thwn 2 wire.
The following are the meanings represented by the letters of the three models
THHN wire
T = Thermoplastic
HH = High Heat Resistance
N = Nylon Coated
Temp Rating: 90° C in dry locations
THWN wire
T = Thermoplastic
H = Heat and
W = Water Resistance
N = Nylon Coated
Temp Rating: 90° C in dry locations and 75° C in wet locations
THWN-2 wire
T = Thermoplastic
H = Heat and
W = Water Resistance
N = Nylon Coated
Temp Rating: 90° C in both dry and wet locations
