Take care of general purpose wiring in branch circuits, control circuits, machine tools, and appliances with THHN, the most commonly used building wire. THHN (thermoplastic high heat-resistant nylon) wire is available in a wider range of gauges and is more heat resistant.
THHN is a thermoplastic, high-heat resistant, nylon coated wire. THWN is essentially the same as THHN, but can withstand higher temperatures in both dry and wet conditions. THHN can only withstand temperatures of up to 75°C in wet conditions, while THWN can handle up to 90°C. In most cases, these wires can be used interchangeably in general purpose wiring in branch circuits, control circuits, machine tools, and appliances.