220V Wire Size Calculator

About the 220V Wire Size Calculator

Most heavy residential appliances — electric ranges, dryers, water heaters, air conditioners, and EV chargers — operate on 220/240V circuits. Proper wire sizing ensures these high-draw devices receive adequate voltage without overheating the conductors.

The National Electrical Code (NEC) sets minimum wire sizes based on ampacity (current-carrying capacity) and recommends keeping voltage drop under 3% for branch circuits. At 240V, the voltage drop budget is more generous than at 120V, but large appliances drawing 30-50 amps over long distances can still exceed the limit if wire is undersized.

This calculator determines the correct wire gauge for any 220/240V load by computing the required amperage from wattage and power factor, then checking both ampacity and voltage drop requirements. It supports copper and aluminum conductors and displays a complete NEC wire table for comparison. For real installations, confirm the result against the appliance nameplate, breaker size, and any local code amendments, especially on long runs where voltage drop can push you up a gauge.

When This Page Helps

Sizing wire for 240V circuits requires balancing NEC ampacity requirements with voltage-drop calculations — and the consequences of getting it wrong include tripped breakers, overheated wire, and voided appliance warranties.

This calculator combines both checks in one step, recommends the minimum compliant wire gauge, and shows a full comparison table so you can evaluate alternatives. It is invaluable for homeowners planning new circuits, electricians quoting jobs, and inspectors verifying installations.

How to Use the Inputs

1. Enter the appliance wattage or select a common appliance preset.
2. Choose the system voltage (220V, 230V, or 240V).
3. Enter the one-way wire distance from the breaker panel to the appliance.
4. Select copper or aluminum conductor.
5. Set the maximum allowable voltage drop percentage.
6. Adjust the power factor for motor loads (1.0 for resistive loads).
7. Review the recommended wire gauge, voltage drop, and full comparison table.

Example Calculation

Tips & Best Practices

• Size the wire to the breaker rating, not the actual load — a 30A breaker requires 10 AWG wire regardless of whether the load draws 22A or 28A.
• For motor loads, use the nameplate amperage rather than calculating from watts, as motors have high inrush current.
• A 240V circuit uses a double-pole breaker and does not share a neutral with another circuit.
• Use flexible conduit or MC cable for the last few feet to an appliance for easier connection.
• In garages and unfinished basements, 240V circuits typically require GFCI protection per recent NEC editions.
• Label both breaker poles and the outlet clearly to prevent accidental use.

Sizing Wire for Common 240V Appliances

Electric ranges typically draw 40-50A and require 6 AWG copper on a 50A breaker. Electric dryers draw 24-30A and use 10 AWG on a 30A breaker for short runs. Water heaters are commonly 4500W (18.75A) on a 30A breaker with 10 AWG wire. Level 2 EV chargers range from 16A to 48A; a 48A charger needs a 60A breaker with 6 AWG copper.

For each appliance, verify the nameplate rating and consult your local code. The NEC provides minimum requirements, but local amendments may be stricter.

Voltage Drop Considerations at 240V

Because 240V provides twice the voltage of 120V circuits, the same wattage requires half the current, which means proportionally less voltage drop. A 5400W load draws only 22.5A at 240V versus 45A at 120V. This is one reason heavy appliances use 240V — it allows smaller wire for the same power delivery.

However, long runs to detached garages, barns, or workshops can still accumulate significant drop. At 200 feet with a 40A load, even 6 AWG copper drops about 7.8V (3.3%). Upsizing to 4 AWG reduces this to about 4.9V (2.0%).

Aluminum vs. Copper for 240V Circuits

Aluminum feeders are common for large 240V circuits because they cost 30-50% less than copper for equivalent ampacity. For a 100A sub-panel feeder, 1 AWG aluminum costs roughly the same as 3 AWG copper but is much lighter. Modern aluminum alloys (AA-8000 series) are more reliable than the older AA-1350 alloy that caused problems in the 1960s-70s. Always use connectors specifically rated for aluminum and apply anti-oxidant compound.

Frequently Asked Questions

• What wire size for a 240V dryer?

  Most dryers draw 24-30A. A 10 AWG copper wire (30A breaker) suffices for short runs. For runs over 50 feet, consider 8 AWG.

• What gauge wire for a 240V EV charger?

  A 32A Level 2 charger on a 40A breaker typically needs 8 AWG copper. A 48A charger on a 60A breaker requires 6 AWG copper.

• Do I need a neutral wire for 240V?

  Pure 240V loads (water heaters, baseboard heaters) do not need a neutral. Appliances that also use 120V (ranges, dryers) require a neutral conductor.

• Is 220V the same as 240V?

  In the US, the nominal voltage is 240V split-phase. "220V" is a common colloquial term. Actual voltage ranges from 216V to 253V depending on utility and load conditions.

• Can I use aluminum wire for 240V circuits?

  Yes, aluminum is commonly used for large 240V feeders (50A+). Use AL-rated connectors and anti-oxidant paste. Aluminum is not recommended for 15-20A branch circuits.

• What breaker size do I need for 240V?

  The breaker must match or exceed the appliance rating. A 5400W dryer at 240V draws 22.5A, requiring a 30A double-pole breaker. Size the wire to the breaker, not just the load.