What is the minimum size THW branch circuit conductors required for a 240-volt, 4-kilowatt electric baseboard heater?

To determine the minimum size THW branch circuit conductors required for a 240-volt, 4-kilowatt electric baseboard heater, we first need to calculate the current that the heater will draw.

Using the formula for power (P = VI), where P is power in watts, V is voltage in volts, and I is current in amperes, we can rearrange the formula to solve for current:

I = P / V.

For a 4-kilowatt heater at 240 volts:

I = 4000 watts / 240 volts = approximately 16.67 amps.

When selecting the appropriate conductor size, it's essential to consider the National Electrical Code (NEC) requirements, which include taking into account the continuous load demand. According to NEC guidelines, for continuous loads, conductors should be sized for 125% of the load.

Calculating 125% of the load:

Continuous load = 16.67 amps × 1.25 = approximately 20.84 amps.

Based on the NEC ampacity tables, a 10 AWG copper conductor can safely handle up to 30 amps, making it suitable for this application.

Since 12 AWG conductors are rated for