Dishwashers can vary in electrical needs. The largest electrical consumption is the heater, and the bigger the heater, the higher the amp draw. Most functions that vary between manufacturers are pretty standard or are low-amp draws and are not nearly as relevant as the heater. The average dishwasher breaker size will be on a minimum of a 15 amps at 120-volt dedicated circuit breaker. Choosing a breaker for your application will depend on the power requirements of your specific dishwasher and the necessary upgrades to comply with some newer regulations.
Dishwasher Circuit Breaker
Dishwashers should be on their own separate circuits, meaning nothing else should be on that circuit or running off that individual breaker. As of 2014, the National Electrical Code (NEC) had already required circuits feeding kitchens to be AFCI (arc-fault circuit-interrupter) protected. These AFCI devices apply to 15 and 20 amp 125-volt circuits, providing protection from arc faults that could start an electrical fire. An arc fault is much like a short or arcing that can be caused from various conditions, like cuts in the wiring or electrical cord, high mechanical stress, and even heat and humidity, like what comes from a dishwasher.
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As of 2020, the NEC requires additional GFCI (ground-fault circuit-interrupter) protection, which is also applied to 15- and 20-amp circuits. Even though dishwashers deal with water and electricity, GFCI protection applied to kitchen counters, bathrooms, and laundry rooms until this code was changed. Many electricians install breakers that are both AFCI and GFCI protected to satisfy this newer code.
Dishwasher Amps and Voltage
All residential dishwashers operate on the nominal voltage of 120 volts but not the same current. Current is measured in amps, and these amps are the size of the breaker you may require. To figure the amps, read the label of your specific appliance to find the dishwasher's amp draw and match the breaker accordingly.
Figuring a Dishwasher's Amp Draw
Sometimes, the amps are not spelled out so plainly. In this case, you will need to figure it out with some simple math. You can derive the dishwasher amps draw by dividing the power by the voltage. For example, if your dishwasher shows it uses 1,500 watts and the voltage is 120 volts, then 1,500/120 gives you 12.5 amps of current draw. In this application, a 15-amp breaker will work.
Dishwasher Breaker Size
If your circuit is already wired and you are upgrading your dishwasher to one with more power, then you may need to upgrade the wiring as well. If you need to upgrade to a larger breaker, make sure that the wiring can handle the extra current. A 15-amp circuit only requires 14-gage wire, but if you need to upgrade to the 20-amp breaker, you will need to upgrade the wiring to 12-gauge wire. If this is necessary, you might want to consider having a professional take care of this and upgrade the circuit to meet the newer NEC standards.
Dishwasher Keeps Tripping Breaker
If your new dishwasher keeps tripping the breaker, check to make sure there are no other appliances on that circuit. Re-read the label of the new dishwasher and make sure the right-size breaker and wall outlet are installed on the circuit. Check to make sure the circuit and all the breakers are wired properly with no electrical shorts in the wiring possibly caused by a nail or a loose connection.
If the circuit breaker keeps tripping, it is more than likely doing what it is designed to do: protect your home. If you investigate and still find nothing, a call to the pros might be necessary for peace of mind.