How Many Amps Does an Appliance Use?

A household refrigerator uses about 6 running amps at 120 volts (roughly 700 watts), but the compressor motor can surge to 12 to 15 amps for a moment at startup. A circuit of its own is the typical choice. In a dwelling kitchen the code puts the refrigerator receptacle on one of the 20A small-appliance circuits, or permits an individual branch circuit rated 15A or more for it (NEC 210.52(B)(1) and its Exception No. 2). Divide the nameplate watts by 120 to get your unit's exact running amps.

An electric dryer draws about 21 to 24 amps at 240 volts (around 5,000 watts) and is installed on a dedicated 30A / 240V circuit with 10 AWG copper wire. A gas dryer only uses its 120V controls, about 5 amps. Always size to the nameplate; a few large dryers need a 40A circuit.

A full-size microwave uses about 10 amps at 120 volts (roughly 1,200 watts of input power, which is more than its cooking-power rating). A countertop unit may plug into one of the kitchen's 20A small-appliance circuits (NEC 210.52(B)(1)); a built-in or over-the-range unit follows its installation instructions, which NEC 110.3(B) makes binding, and a dedicated 20A circuit is the common choice for it.

A dishwasher uses about 10 to 12 amps at 120 volts (around 1,400 watts with the heating element on). The code permits it to share a circuit that supplies only fastened-in-place appliances, such as a disposal, within that circuit's rating (NEC 210.23(B)); its installation instructions, which NEC 110.3(B) makes binding, name the circuit it needs, and a dedicated 15A or 20A circuit is the common choice. It is GFCI protected under the current NEC. The heating element for dry cycles is what pushes the current toward the top of that range.

A window air conditioner uses about 5 to 13 amps at 120 volts depending on size: a small 5,000 BTU unit is around 5 amps, and a large 12,000 BTU unit can reach 12 to 13 amps, with a brief compressor surge above that. Large units may need a dedicated 20A circuit or a 240V outlet; check the unit's plug type and nameplate.

Divide the appliance's wattage by its voltage: amps = watts / volts. A 1,500 watt space heater on 120V draws 1,500 / 120 = 12.5 amps. For a motor load, add a startup surge of several times that for a fraction of a second. Keep the continuous running load under 80% of the circuit breaker, and always defer to the nameplate rating.