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What Size Breaker Do I Need for a 1500 Watt Heater?

Written by Edwin Jones / Fact checked by Andrew Wright

what size breaker do i need for a 1500 watt heater

You bought a new 1,500-watt heater recently, but now you’re wondering, ‘What size breaker do I need for a 1500 watt heater?’

A 20-amp circuit breaker is generally the minimum requirement for a heater. A 15-amp breaker might not be able to handle the device’s power output during a surge.

Continue reading to gain additional insight into using the right circuit breakers with heaters.

What Size Breaker Do You Need for a 1,500-watt Heater?


A 120v 1500w heater needs a 20-amp circuit breaker. According to the National Electric Code (NEC), circuit breakers’ ratings should equal 125% of the electrical load of devices they support to cater to at least 80% of the power draw.

It’s necessary to understand the calculation needed to arrive at that conclusion. First, it’s vital to know how many amps does a 1500 watt heater use. You need to divide the power of the heater, which is 1,500 watts, by its operating voltage.

In general, when plugging that appliance into a standard wall outlet, the voltage of the electrical setup should be 120 volts. Dividing 1,500 watts by 120 volts will yield 12.5 amps. 125% of 12.5 is 15.6.

Connecting a 1500 watt heater on 15 amp circuit won’t be a viable assembly. Although the heater can pull approximately 80% electricity from the circuit, the setup might not have a sufficient capacity if a surge occurs. Hence, one needs to go up a breaker size.

Does a 1500 Watt Heater Need Its Own Circuit?


A heater with 1500 watts at 120 volts is a high-load appliance, which means it needs its own circuit breaker. Connecting another device to the same outlet as the heater may trip the breaker.

Which Circuit Breaker Is for Heater?

Generally, you have two options to use for your heater’s circuit breaker. These choices are:

1. Toggle Switch

In particular, you can use a toggle switch with a fuse. As its name implies, this module allows users to turn the heater on and off by flipping the control component from the service panel.

An armature is usually within the switch, which activates or deactivates the circuit when pressed. Also, you can usually use toggle switches with fuses for older heaters.

2. Single-Pole Switch

Modern heaters often use the standard single-pole switch. It typically has a design that’s similar to circuit breakers used for lighting fixtures. It also acquired its name because of the single switch that controls its two states.

Frequently Asked Questions


What Size Wire For A 20-Amp Circuit?

20-amp circuits, particularly for heaters, typically use a 12 AWG wire, thanks to its 25-amp capacity. You may also use a 14 AWG wire, which has a 20-amp capacity, but this option might not provide the setup with a reasonable power allowance if a surge occurs.


Now that you’re at the end of this post, you should have an answer to the question, ‘What size breaker do I need for a 1500 watt heater?’ Remember, you should use a circuit breaker that has a capacity above the appliance’s standard power draw.

If not, the circuit breaker can trip, particularly during electricity surges. Also, it’s not ideal for connecting another appliance to the outlet and breaker of the heater.

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