Wire Size GuideNEC 2023 · 2026 · Updated Apr 2026

What wire size for a 20 amp circuit?

Q: What is the minimum wire size for a 20 amp circuit?

The minimum wire size is 12 AWG copper or 10 AWG aluminum per NEC 2023 Table 310.16 with 110.14(C) termination limits applied. For long runs, you may need to upsize to account for voltage drop. See the max distance table above.

Q: Can I use aluminum wire for a 20 amp circuit?

Yes. 10 AWG aluminum handles 20A. Aluminum requires anti-oxidant compound and AL-rated terminals (marked AL/CU on the device). It costs roughly 40-60% less than copper but requires a larger gauge for equivalent ampacity. See the 12 AWG copper vs aluminum comparison.

Q: How far can I run 12 AWG wire on a 20 amp circuit?

At 120V, 12 AWG copper can run approximately 45 feet before exceeding the 3% voltage drop recommendation. For longer distances, upsize to the next gauge. Use the voltage drop calculator for your exact scenario.

Q: What breaker size for a 20 amp circuit?

Use a 20A breaker. The breaker must match the circuit rating, not the wire ampacity. For continuous loads (like EV chargers), the breaker must be rated at 125% of the load per NEC 210.19(A)(1).

For a 20A circuit on a 20A breaker: Use 12 AWG copper (25A capacity) or 10 AWG aluminum (30A capacity). Common applications: kitchen countertop outlets, bathrooms, garages, and dedicated appliance circuits.

Copper12 AWG

Aluminum10 AWG

Breaker20A

Voltage120V

You\'re adding a kitchen circuit during a remodel, wiring a bathroom that needs its own 20A per code, or running a dedicated outlet for a window AC unit that keeps tripping the shared circuit. The 20A circuit is where most residential wiring projects start.

All valid wire sizes for a 20 amp circuit

A 20 amp circuit handles higher-draw appliances and is required by code in kitchens, bathrooms, garages, and laundry areas. The minimum wire is 12 AWG copper, limited to 20A per NEC 240.4(D).

NEC 210.11(C) requires dedicated 20A circuits for bathrooms, kitchens (minimum two small-appliance circuits), and laundry. These cannot share loads with other rooms.

Common mistake: The most common 20A mistake is running 14 AWG wire and putting it on a 20A breaker. NEC 240.4(D) prohibits this - 14 AWG is limited to 15A maximum overcurrent protection. The second most common: forgetting that kitchen, bathroom, and laundry 20A circuits cannot serve other rooms per 210.11(C).

Any gauge with ampacity equal to or greater than 20A per NEC 2023 Table 310.16, after 110.14(C) termination limits are applied. Smaller gauge number means thicker wire, higher cost, but lower voltage drop.

Gauge	Material	Capacity	Max distance (3% drop)	Conduit
12 AWG (minimum)	Copper	25A	45 ft	1/2" EMT
10 AWG	Copper	35A	72 ft	3/4" EMT
8 AWG	Copper	50A	115 ft	3/4" EMT
6 AWG	Copper	65A	182 ft	3/4" EMT
4 AWG	Copper	85A	291 ft	1" EMT
3 AWG	Copper	100A	365 ft	1" EMT
2 AWG	Copper	115A	461 ft	1" EMT
1 AWG	Copper	130A	588 ft	1-1/4" EMT
1/0 AWG	Copper	150A	731 ft	1-1/4" EMT
2/0 AWG	Copper	175A	937 ft	1-1/2" EMT
3/0 AWG	Copper	200A	1153 ft	2" EMT
4/0 AWG	Copper	230A	1500 ft	2" EMT
10 AWG (minimum)	Aluminum	30A	44 ft	1/2" EMT
8 AWG	Aluminum	40A	70 ft	3/4" EMT
6 AWG	Aluminum	50A	111 ft	3/4" EMT
4 AWG	Aluminum	65A	177 ft	3/4" EMT
3 AWG	Aluminum	75A	223 ft	1" EMT
2 AWG	Aluminum	90A	283 ft	1" EMT
1 AWG	Aluminum	100A	357 ft	1" EMT
1/0 AWG	Aluminum	120A	447 ft	1-1/4" EMT
2/0 AWG	Aluminum	135A	566 ft	1-1/4" EMT
3/0 AWG	Aluminum	155A	714 ft	1-1/2" EMT
4/0 AWG	Aluminum	180A	909 ft	2" EMT

Maximum wire run distance

One-way distance in feet before voltage drop exceeds 3%, per NEC Chapter 9 Table 8 resistance values. If your run is longer than these distances, upsize one gauge.

Gauge	Material	120V	208V	240V	480V
12 AWG	Copper	45 ft	78 ft	90 ft	181 ft
10 AWG	Copper	72 ft	126 ft	144 ft	291 ft
8 AWG	Copper	115 ft	200 ft	230 ft	461 ft
6 AWG	Copper	182 ft	319 ft	365 ft	731 ft
4 AWG	Copper	291 ft	508 ft	588 ft	1153 ft
3 AWG	Copper	365 ft	638 ft	731 ft	1500 ft
2 AWG	Copper	461 ft	810 ft	937 ft	1875 ft
1 AWG	Copper	588 ft	1000 ft	1153 ft	2307 ft
1/0 AWG	Copper	731 ft	1304 ft	1500 ft	3000 ft
2/0 AWG	Copper	937 ft	1578 ft	1875 ft	3750 ft
3/0 AWG	Copper	1153 ft	2000 ft	2307 ft	5000 ft
4/0 AWG	Copper	1500 ft	2500 ft	3000 ft	6000 ft
10 AWG	Aluminum	44 ft	76 ft	88 ft	176 ft
8 AWG	Aluminum	70 ft	121 ft	140 ft	280 ft
6 AWG	Aluminum	111 ft	193 ft	222 ft	447 ft
4 AWG	Aluminum	177 ft	306 ft	352 ft	714 ft
3 AWG	Aluminum	223 ft	384 ft	447 ft	882 ft
2 AWG	Aluminum	283 ft	491 ft	566 ft	1111 ft
1 AWG	Aluminum	357 ft	612 ft	714 ft	1428 ft
1/0 AWG	Aluminum	447 ft	769 ft	882 ft	1764 ft
2/0 AWG	Aluminum	566 ft	967 ft	1111 ft	2307 ft
3/0 AWG	Aluminum	714 ft	1250 ft	1428 ft	3000 ft
4/0 AWG	Aluminum	909 ft	1578 ft	1764 ft	3750 ft

Common 20A circuit projects

kitchen small appliance circuit

NEC 210.11(C)(1) requires at least two 20A small-appliance circuits serving kitchen countertop receptacles. These circuits can only serve the kitchen and dining area countertop outlets - no refrigerator, no dishwasher, no other rooms. Run 12/2 NM-B from the panel to the first kitchen outlet, then daisy-chain to additional outlets.

bathroom outlet

Every bathroom needs at least one dedicated 20A circuit per 210.11(C)(3). This circuit can serve one or multiple bathrooms but cannot serve any other room. Use 12/2 NM-B with a GFCI breaker or GFCI at the first receptacle. The receptacle must be within 3 feet of the outside edge of each sink basin.

garage outlets

Garage circuits are typically 20A with 12/2 NM-B. All garage receptacles require GFCI protection, including the ceiling outlet for the garage door opener. For workshops, consider running two 20A circuits to avoid tripping when running a compressor and a saw simultaneously.

outdoor outlets

Outdoor receptacles require GFCI protection per 210.8(A)(3) and weather-resistant (WR) receptacles with in-use covers. Run 12/2 NM-B to the exterior wall, transition to weatherproof box through conduit or LB fitting. Two outdoor receptacles are required - one front, one back - per 210.52(E).

Frequently asked questions

What is the minimum wire size for a 20 amp circuit?

The minimum wire size is 12 AWG copper or 10 AWG aluminum per NEC 2023 Table 310.16 with 110.14(C) termination limits applied. For long runs, you may need to upsize to account for voltage drop. See the max distance table above.

Can I use aluminum wire for a 20 amp circuit?

Yes. 10 AWG aluminum handles 20A. Aluminum requires anti-oxidant compound and AL-rated terminals (marked AL/CU on the device). It costs roughly 40-60% less than copper but requires a larger gauge for equivalent ampacity. See the 12 AWG copper vs aluminum comparison.

How far can I run 12 AWG wire on a 20 amp circuit?

At 120V, 12 AWG copper can run approximately 45 feet before exceeding the 3% voltage drop recommendation. For longer distances, upsize to the next gauge. Use the voltage drop calculator for your exact scenario.

What breaker size for a 20 amp circuit?

Use a 20A breaker. The breaker must match the circuit rating, not the wire ampacity. For continuous loads (like EV chargers), the breaker must be rated at 125% of the load per NEC 210.19(A)(1).

Do I need GFCI on a 20 amp circuit?

GFCI requirements depend on location, not amperage. NEC 2023 requires GFCI in kitchens, bathrooms, garages, outdoors, basements, laundry areas, and near sinks. Check the GFCI requirements by room for your specific installation.

Common products for 12 AWG Copper circuits

🧵Wire Roll12 AWG solid copper, 500ftCheck prices on Amazon (paid link) ⚡20A BreakerStandard pairing for 12 AWGCheck prices on Amazon (paid link) 🔌GFCI OutletRequired in kitchens, baths, garagesCheck prices on Amazon (paid link) 🔧Wire Strippers12 AWG compatibleCheck prices on Amazon (paid link)

As an Amazon Associate we earn from qualifying purchases.

Requirements vary by state. NEC edition, licensing, permits, and GFCI rules differ by jurisdiction. Check your state or pick it below for personalized info across WireRef.

Important: For reference only. Not a substitute for a licensed electrician. Electrical work can cause serious injury, death, fire, or property damage if performed incorrectly. Always hire a licensed electrician for electrical work, especially for service upgrades, panel work, and 240V circuits. Values are derived from NFPA 70 (NEC) for educational purposes. Always verify against your locally adopted NEC edition and amendments - local jurisdictions may enforce stricter requirements. WireRef provides reference information only and is not responsible for work performed based on this content. NEC® is a registered trademark of the National Fire Protection Association. Free NEC access via NFPA · OSHA Electrical Safety · Terms of use.

NEC 2023 references verified April 2026