Question 1

What size wire do I need for 50 amps?

Accepted Answer

For a 50-amp circuit (e.g., an EV charger or range) at 120/240V, use 6 AWG copper or 4 AWG aluminum for runs under about 100 ft. Longer runs may need to size up for voltage drop.

Question 2

What size wire for 30 amps?

Accepted Answer

A 30-amp circuit (dryer, water heater, RV hookup) needs 10 AWG copper or 8 AWG aluminum for typical runs under 100 ft. Use our calculator for longer runs.

Question 3

Can I use aluminum wire instead of copper?

Accepted Answer

Yes. Aluminum is cheaper but needs a larger gauge — roughly two sizes larger than copper for the same ampacity. Terminations must be rated for aluminum (anti-oxidant compound required).

Question 4

How does wire length affect wire size?

Accepted Answer

Longer runs have higher resistance, which increases voltage drop. To stay within the recommended 3% drop, longer runs may require one or two sizes larger wire than the ampacity chart alone suggests.

Question 5

Is this wire size calculator code compliant?

Accepted Answer

It follows the NEC ampacity basics and the 3% voltage-drop guideline for branch circuits. Always verify final sizing against the current NEC tables and local code — this is an estimate, not a permit document.

AWG	Max Amps (copper)	Common Use
14	15	Lights, 15A outlets
12	20	Kitchen / bath / garage outlets
10	30	Dryer, water heater, AC (30A)
8	40	Ranges, EV chargers (40A)
6	55	EV chargers, subpanels (50–60A)
4	70	Large subpanels, welders (70A)

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Wire Size Quick Reference (Copper)

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