NEC Wire Sizing
What Size Wire for Each Appliance?
The breaker and wire for the appliances people wire most often, at a glance, each computed from the NEC tables. Pick an appliance for the full detail, code basis, and calculator.
| Appliance | Volts | Breaker | Copper Wire | Ground |
|---|---|---|---|---|
| Electric Dryer | 240V | 30A | #10 | #10 |
| Electric Range | 240V | 50A | #6 | #10 |
| Electric Wall Oven | 240V | 40A | #8 | #10 |
| Electric Cooktop | 240V | 40A | #8 | #10 |
| Electric Water Heater | 240V | 30A | #10 | #10 |
| Hot Tub (GFCI) | 240V | 50A | #6 | #10 |
| Dishwasher (GFCI) | 120V | 20A | #12 | #12 |
| Garbage Disposal | 120V | 15A | #14 | #14 |
| Built-In Microwave (GFCI) | 120V | 20A | #12 | #12 |
| Refrigerator (GFCI) | 120V | 20A | #12 | #12 |
| Freezer (GFCI) | 120V | 20A | #12 | #12 |
| Garage Door Opener (GFCI) | 120V | 20A | #12 | #12 |
Values are the standard circuit for a typical unit. Motor-driven appliances (well pumps, air compressors) and nameplate-MCA loads (mini splits, central AC) follow NEC Articles 430 and 440 and are sized to their data plate.
Pick an Appliance
Electric Dryer
#10 copper on a 30A / 240V circuit.
Electric Range
#6 copper on a 50A / 240V circuit.
Electric Wall Oven
#8 copper on a 40A / 240V circuit.
Electric Cooktop
#8 copper on a 40A / 240V circuit.
Electric Water Heater
#10 copper on a 30A / 240V circuit.
Hot Tub
#6 copper on a 50A / 240V circuit, GFCI.
Dishwasher
#12 copper on a 20A / 120V circuit, GFCI.
Garbage Disposal
#14 copper on a 15A / 120V circuit.
Built-In Microwave
#12 copper on a 20A / 120V circuit, GFCI.
Refrigerator
#12 copper on a 20A / 120V circuit, GFCI.
Freezer
#12 copper on a 20A / 120V circuit, GFCI.
Garage Door Opener
#12 copper on a 20A / 120V circuit, GFCI.
Central Air Conditioner
Sized to the nameplate MCA and MOCP (NEC 440), not the tonnage. Typical 2-3 ton = #10 Cu.
Mini Split
Inverter ductless unit: size to the nameplate MCA. Typical 12k BTU = #14 Cu on 15-20A.
Tankless Water Heater
Large multi-circuit load: an 18 kW unit draws ~75A across 2-3 circuits of #8 Cu.
Well Pump
Motor load (NEC 430): small code-minimum wire, breaker to 250% FLC, upsized for voltage drop.
Air Compressor
120V plug-in vs hardwired 240V motor circuit; size from the nameplate amps, not peak HP.
Pool Pump
240V motor plus the NEC 680 GFCI, 8 AWG equipotential bond, and disconnect rules.
Baseboard Heater
Continuous load (NEC 424.4(B)): a 20A/#12 circuit carries 3,840W; add up the heaters per circuit.
Electric Furnace
Large electric heat, by kW: 10 kW = ~60A/#6; 15 kW+ usually splits across 2-3 circuits.
Welder
NEC 630 duty cycle: 50A/#6 on a NEMA 6-50, or size the conductor by duty-cycle factor.
3-Wire vs 4-Wire Dryer & Range
Guide: why 4-prong, when a 3-prong outlet is still legal (NEC 250.140), matching cord to outlet.
Wire Size Calculator
Size any load, distance, and conditions per NEC 310.16 with derating.
EV Charger Wiring
Wire, breaker, and panel for a Level 2 EV charger install.
120V Induction Range Circuit
The battery-buffered plug-in range that runs on a 120V branch instead of a 240V range circuit, and its shared-circuit rule.
Frequently Asked Questions
How do I know what size wire an appliance needs?
Start with the appliance nameplate, which lists the minimum circuit ampacity and the maximum breaker. Size the breaker to that (rounded to a standard size), then match the conductor to the breaker at the NEC Table 310.16 column for your terminals: 60C for NM-B cable and terminations 100A and under, 75C for THHN in conduit on 75C-rated lugs. The table on this page gives the typical answer for common appliances, but the nameplate always governs.
Why does an electric water heater use a bigger circuit than its amp draw?
Because NEC 422.13 treats a fixed storage water heater as a continuous load, so the circuit is sized at 125% of the draw. A 4500W / 240V heater pulls 18.75A, and 18.75 x 1.25 = 23.4A. The NEC code minimum is the next standard breaker up, 25A (NEC 240.6(A)); the tank is marked and installed on the standard 30A breaker with #10 copper.
Do 240V appliances need a neutral?
It depends on the appliance. A pure 240V load (like a water heater or baseboard heater) needs only two hots and a ground. Appliances with 120V controls or accessories (modern electric ranges and dryers) need two hots, a neutral, and a ground, which is why they use a 4-wire cord and receptacle (NEMA 14-30 for dryers, 14-50 for ranges) rather than the old 3-wire style.
Keep going