Wire Size GuideNEC 2023 · 2026 · Updated Apr 2026

What wire size for a 30 amp circuit?

Q: What is the minimum wire size for a 30 amp circuit?

The minimum wire size is 10 AWG copper or 8 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 30 amp circuit?

Yes. 8 AWG aluminum handles 30A. 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 10 AWG copper vs aluminum comparison.

Q: How far can I run 10 AWG wire on a 30 amp circuit?

At 240V, 10 AWG copper can run approximately 96 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 30 amp circuit?

Use a 30A 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 30A circuit on a 30A breaker: Use 10 AWG copper (35A capacity) or 8 AWG aluminum (40A capacity). Common applications: electric dryers, water heaters, and small HVAC equipment.

Copper10 AWG

Aluminum8 AWG

Breaker30A

Voltage240V

You\'re replacing a dryer outlet, adding a water heater circuit, or an inspector flagged your existing 30A wiring during a remodel. Most 30A questions come from the dryer circuit - it\'s the first 240V circuit most homeowners encounter.

All valid wire sizes for a 30 amp circuit

The 30 amp wire size is 10 AWG copper or 8 AWG aluminum. A 30 amp/240V circuit is the standard for electric dryers and many water heaters. NEC 2023 now requires GFCI for laundry circuits per 210.8(A)(10).

NEC 240.4(D) limits 10 AWG copper to 30A maximum. For dryer circuits, NEC 210.52(F) requires a receptacle within 6 feet of the intended appliance location.

Common mistake: The most common 30A wiring mistake is using 10/2 NM-B when you need 10/3 for the dryer\'s neutral. A dryer needs four wires: two hots, a neutral, and a ground. The old 3-wire dryer cord (no separate ground) is only legal on existing installations - new work requires a 4-wire setup with a 14-30R receptacle.

Any gauge with ampacity equal to or greater than 30A 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
10 AWG (minimum)	Copper	35A	96 ft	3/4" EMT
8 AWG	Copper	50A	153 ft	3/4" EMT
6 AWG	Copper	65A	243 ft	3/4" EMT
4 AWG	Copper	85A	389 ft	1" EMT
3 AWG	Copper	100A	491 ft	1" EMT
2 AWG	Copper	115A	625 ft	1" EMT
1 AWG	Copper	130A	769 ft	1-1/4" EMT
1/0 AWG	Copper	150A	1000 ft	1-1/4" EMT
2/0 AWG	Copper	175A	1250 ft	1-1/2" EMT
3/0 AWG	Copper	200A	1578 ft	2" EMT
4/0 AWG	Copper	230A	2000 ft	2" EMT
8 AWG (minimum)	Aluminum	40A	93 ft	3/4" EMT
6 AWG	Aluminum	50A	148 ft	3/4" EMT
4 AWG	Aluminum	65A	236 ft	3/4" EMT
3 AWG	Aluminum	75A	297 ft	1" EMT
2 AWG	Aluminum	90A	375 ft	1" EMT
1 AWG	Aluminum	100A	476 ft	1" EMT
1/0 AWG	Aluminum	120A	600 ft	1-1/4" EMT
2/0 AWG	Aluminum	135A	750 ft	1-1/4" EMT
3/0 AWG	Aluminum	155A	937 ft	1-1/2" EMT
4/0 AWG	Aluminum	180A	1200 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
10 AWG	Copper	48 ft	83 ft	96 ft	193 ft
8 AWG	Copper	77 ft	133 ft	153 ft	309 ft
6 AWG	Copper	121 ft	211 ft	243 ft	491 ft
4 AWG	Copper	194 ft	337 ft	389 ft	769 ft
3 AWG	Copper	243 ft	422 ft	491 ft	967 ft
2 AWG	Copper	309 ft	535 ft	625 ft	1250 ft
1 AWG	Copper	389 ft	681 ft	769 ft	1578 ft
1/0 AWG	Copper	491 ft	857 ft	1000 ft	2000 ft
2/0 AWG	Copper	625 ft	1071 ft	1250 ft	2500 ft
3/0 AWG	Copper	789 ft	1363 ft	1578 ft	3000 ft
4/0 AWG	Copper	1000 ft	1666 ft	2000 ft	3750 ft
8 AWG	Aluminum	46 ft	81 ft	93 ft	187 ft
6 AWG	Aluminum	74 ft	128 ft	148 ft	297 ft
4 AWG	Aluminum	118 ft	204 ft	236 ft	468 ft
3 AWG	Aluminum	148 ft	258 ft	297 ft	600 ft
2 AWG	Aluminum	188 ft	326 ft	375 ft	750 ft
1 AWG	Aluminum	238 ft	410 ft	476 ft	937 ft
1/0 AWG	Aluminum	300 ft	517 ft	600 ft	1200 ft
2/0 AWG	Aluminum	375 ft	652 ft	750 ft	1500 ft
3/0 AWG	Aluminum	476 ft	833 ft	937 ft	1875 ft
4/0 AWG	Aluminum	600 ft	1034 ft	1200 ft	2500 ft

Common 30A circuit projects

electric dryer

A 240V dryer circuit uses a 30A double-pole breaker with 10/3 NM-B (two hots, neutral, ground). The receptacle is a NEMA 14-30R. NEC 2023 requires GFCI protection on laundry circuits per 210.8(A)(10). Run the cable from the panel to a box mounted at dryer-outlet height, typically 12 inches above the floor behind the dryer.

tankless water heater

Most tank-style water heaters draw 18-22A on a 30A/240V circuit. Use 10/2 NM-B (no neutral needed - water heaters are 240V-only loads). The disconnect can be the breaker itself if the panel is within sight, otherwise install a disconnect within sight of the unit. Check the nameplate - some larger units need 40A or dual circuits.

window AC unit (large)

A 240V window AC in the 15,000-25,000 BTU range typically needs a dedicated 30A circuit. Use 10/2 NM-B to a NEMA 6-30R or hardwired disconnect. The unit\'s nameplate will specify the minimum circuit ampacity and maximum breaker size. GFCI protection is required if the receptacle is within 6 feet of a sink.

Frequently asked questions

What is the minimum wire size for a 30 amp circuit?

The minimum wire size is 10 AWG copper or 8 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 30 amp circuit?

Yes. 8 AWG aluminum handles 30A. 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 10 AWG copper vs aluminum comparison.

How far can I run 10 AWG wire on a 30 amp circuit?

At 240V, 10 AWG copper can run approximately 96 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 30 amp circuit?

Use a 30A 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 30 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 10 AWG Copper circuits

🧵Wire Roll10 AWG copper, 100ftCheck prices on Amazon (paid link) ⚡30A BreakerStandard pairing for 10 AWGCheck prices on Amazon (paid link) 🔌Dryer Cable10/3 NM-B for 30A dryersCheck prices on Amazon (paid link)

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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