For the most part, 120-volt household electric circuits are protected by breakers with only two current ratings, 15 amps and 20 amps. According to GE Appliances, you can use either one for a dishwasher circuit. The one you use depends on the power requirements of the dishwasher. The National Electric Code (NEC), however, now requires a dedicated circuit for the dishwasher controlled by a 15-amp breaker.
Since 2014, the NEC has required Ground Fault Current Interrupting (GFCI) protection on the dishwasher circuit, and Arc Fault Current Interrupting (AFCI) protection is required in receptacles throughout the kitchen. The easiest way to meet all the NEC requirements is to install a 15-amp GFCI/AFCI circuit breaker in the panel to control the dishwasher circuit.
The Dishwasher Circuit Breaker
IN 2017, the NEC was revised to require the following kitchen appliances to be controlled by dedicated circuit breakers:
- garbage disposal
- microwave oven
- electric range
The refrigerator and microwave require 20-amp breakers, but the dishwasher and garbage disposal need 15-amp ones unless they draw enough power to warrant a bigger breaker. Keep in mind that 14-gauge wire is permitted for 15-amp circuits, but not for 20-amp ones. If you upgrade a breaker, you may also have to rewire the circuit.
This code revision is recent, and it doesn't apply to existing circuitry, so it's common for the dishwasher to share a circuit with another appliance, often the garbage disposal. When this is the case, the breaker should be rated for 20 amps, even if the dishwasher and garbage disposal are both rated for 15 amps.
Dishwasher Amps and Voltage
All dishwashers operate at a nominal voltage of 120 volts, but not all draw the same current, and that's what determines the breaker size. If you don't have the manufacturer's specifications, you can determine the current draw by checking the label on the back of the appliance or affixed to the side of the door.
If the label doesn't list current draw specifically, it will specify the amount of power the appliance uses in watts. You can derive the dishwasher amps draw by dividing the power by the voltage. For example, if the dishwasher uses 1,500 watts to heat water and operate the spray arm, then 1,500 watts/120 volts results in a current draw of 12.5 amps. A 15-amp breaker would be sufficient, as long as the circuit isn't shared with any other appliance.
Troubleshooting the Dishwasher Circuit
If your new Maytag, GE or Kenmore dishwasher keeps tripping the breaker, the first thing to do is determine what other appliances share the circuit and unplug one or more. If the breaker continues to trip, even after unplugging all other appliances, the dishwasher is drawing more power than the breaker can handle, and you need a bigger breaker.
It isn't safe or legal, however, to simply exchange a 15-amp breaker for a 20-amp one unless you rewire the circuit with a heavier-gauge wire. You could exchange the power-hungry dishwasher for one that consumes less electricity, but if you want to keep that one, the safe way to operate it is to hire an electrician to install a new 20-amp circuit for it.
One more thing to remember is that when a circuit breaker trips, it's just doing the job it's supposed to do. If it's sized properly for the dishwasher and trips repeatedly, something is probably wrong with the circuit wiring or the wiring inside the dishwasher, and you should call an appliance pro to investigate.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker.com.