Circuit Breakers, Electrical Wiring and Device Wattage
Posted on Oct 4, 2019
I need to install an electric fireplace but I’m not sure if the circuit can handle the load with other devices on. Here’s an explanation of device load, electrical wiring and circuit breakers.
In a typical residential home, you’ll have two types of circuits:
- 15A (amp) circuit using 14 gauge (thin) electrical wire (usually white) connected to a 15A circuit breaker. Based on the formula P (watt) = V (volts) x i (current), the max wattage this circuit can handle before tripping the circuit breaker is 120 V x 15 A = 1800 W. This circuit is usually used for general lighting.
- 20A (amp) circuit using 12 gauge (thick) electrical wire (usually yellow) connected to a 20A circuit breaker. This circuit can support a total load of 120V x 20A = 2400 W. This circuit is usually used for kitchen devices.
You can’t just replace a 15A circuit breaker with a 20A one since the wires going into the 15A circuit breaker are likely 14 gauge (thin) wires. If these wires carry a load greater than 1500 watts, the wire can burn, catch on fire, and burn the house down. When installing new circuits, just always use 12 gauge wiring even if connected to a 15 amp circuit breakers.
In the example above, I have these devices
- electric fireplace (1500 W)
- LG OLED 65″ TV (150 W)
- 2 x LED lamps (2 x 15 W = 30 W)
Total power consumption = 1500 W + 150 W + 30 W = 1680 W. Since this is less than 1800 W (the max wattage for a 15 A circuit), I should be okay, although it would be preferable to put the fireplace on a 20A circuit.