What is the difference between THHN and THWN electric wire?
THHN is short for thermoplastic high-heat resistant nylon-coated wire; it is with better electrical properties and physical properties than common PVC insulation electric wires, which are with better features of heat resistance, rotproofness, self-lubrication and oil resistance. THHN nylon electric wire is used to connect branch circuit and various kinds of electronics.
THWN is short for thermoplastic heat- and waterproofness nylon-coated wire, it is with features of thermoplasticity and water-resistant. The application of THWN is same as THHN, it is known as THWN is evolution of THHN.
In conclusion, the basic difference bewteen THHN and THWN is the waterproofness.