What is the typical gauge of wire used for line voltage applications in HVAC systems?

For line voltage applications in HVAC systems, the typical gauge of wire used is indeed 12 or 14 gauge wire. This wire size is suitable for safely carrying the electrical current required for most residential and light commercial heating, ventilation, and air conditioning systems.

Using 12 or 14 gauge wire provides the necessary balance between sufficient current-carrying capacity and the need to minimize voltage drop over the length of the wire. The National Electrical Code (NEC) guidelines generally recommend these wire sizes for circuits that might handle loads typically found in HVAC systems, which can range from individual units to larger packaged systems.

Larger gauges, like 10 gauge, are generally reserved for larger loads or specialized applications where higher current is required, while smaller gauges like 16 or 18 are usually used in low-power circuits such as control voltages or smaller appliances and are not suitable for typical HVAC line voltage applications. Therefore, 12 or 14 gauge wire is the most common choice for ensuring reliability and safety in HVAC electrical installations.