60 amp wire size
A 60 amp circuit needs 6 AWG copper as THHN in conduit with 75 °C terminations, where it is rated 65 A, or 4 AWG copper in NM-B cable, where the 60 °C column gives 70 A. 6 AWG NM-B is rated only 55 A, which is short of 60 A.
Minimum wire size for 60 A
| Conductor | 60 °C column | 75 °C column |
|---|---|---|
| Copper | 4 AWG | 6 AWG |
| Aluminum | Not listed | 4 AWG |
Usually chosen: 6 AWG copper THHN in conduit, or 4 AWG copper NM-B for a cable run. For an aluminum feeder, 4 AWG aluminum (for example in SER cable) is the 75 °C minimum.
Breaker rating taken as the required ampacity; 240.4(D) limits applied. The charts list no 60 °C aluminum, and 60 °C copper only to 2 AWG (95 A), the largest NM-B. Manufacturer chart values (2017 NEC basis). Verify against the NEC edition adopted locally.
60 A is the classic rating for a subpanel feeder, a hot tub and the larger Level 2 EV chargers. Each brings its own rules, covered after the answer box, along with the next-size-up allowance that sometimes puts 6 AWG cable on a 60 A breaker.
Where 60 amp circuits are used
A 60 A feeder is a common size for a garage, workshop or small accessory building subpanel. A detached building also needs its own disconnecting means and a grounding electrode system, with the feeder's grounded conductor isolated from the equipment ground at the remote panel (250.32).
Hot tubs and spas are frequently specified for 50 A or 60 A, 240 V supplies. Article 680 requires GFCI protection, often provided by a GFCI breaker in a spa panel, and a maintenance disconnect within sight of the tub and at least 5 ft from its inside walls.
A 48 A EV charger, the highest setting for most hard-wired residential units, needs a 60 A circuit after the 125% continuous factor. Some tankless electric water heaters also split their load among two or three 40 A to 60 A circuits, each sized from the manufacturer's data.
Voltage drop at 60 A
6 AWG copper carrying 60 A stays within 3% to about 122 ft at 240 V. A subpanel in a detached shop is often farther than that, and the table shows when the feeder goes up to 4 AWG or 3 AWG copper, or to an aluminum size of equal resistance.
Subpanel feeders rarely carry their full rating continuously, so a designer may base the drop on the calculated load rather than 60 A. A charger at 48 A for hours is closer to the full-load figure.
| One-way length (ft) | Drop at 120 V (%) | Drop at 240 V (%) | Copper for 3% at 120 V | Copper for 3% at 240 V |
|---|---|---|---|---|
| 25 | 1.23 | 0.61 | 6 AWG | 6 AWG |
| 50 | 2.45 | 1.23 | 6 AWG | 6 AWG |
| 75 | 3.68 | 1.84 | 4 AWG | 6 AWG |
| 100 | 4.90 | 2.45 | 3 AWG | 6 AWG |
| 150 | 7.35 | 3.68 | 2 AWG | 4 AWG |
| 200 | 9.81 | 4.90 | 1/0 AWG | 3 AWG |
| 250 | 12.26 | 6.13 | 2/0 AWG | 2 AWG |
| 300 | 14.71 | 7.35 | 2/0 AWG | 2 AWG |
Full rating on a single-phase circuit, copper at 75 °C, stranded.
Breaker pairing
The breaker is a two-pole 60 A device. 6 AWG copper THHN with 75 °C terminations at the panel and at the load is the most economical match.
6 AWG NM-B has an ampacity of 55 A, which is not a standard rating, so NEC 240.4(B) permits protecting it at the next standard rating, 60 A, provided the circuit does not supply more than one receptacle for cord-and-plug loads and the calculated load does not exceed 55 A. A hot tub or charger drawing 48 A fits; a feeder whose load calculation exceeds 55 A does not.
NM-B cable or THHN in conduit
4/3 NM-B is heavy and hard to terminate, which is one reason 60 A runs are so often made as THHN in conduit. Outdoors and underground, the conduit or cable must be listed for wet locations, so THWN-2 conductors or UF cable replace dry-location types.
Where the run is SER cable, which is common for feeders, its conductors are rated 75 °C or 90 °C, but SER installed in thermal insulation inside a house falls back to the 60 °C column, much like NM-B.
Copper or aluminum
4 AWG aluminum reads 65 A at 75 °C on the manufacturer charts and is the aluminum minimum for 60 A. Aluminum is widely used for 60 A subpanel feeders, because panel main lugs are routinely listed for aluminum and the cost saving on a long run is large.
A hot tub disconnect or EV charger may accept copper only. The terminal markings decide, not the feeder's material elsewhere.
Common mistakes
6 AWG NM-B on a 60 A breaker for a feeder
The 240.4(B) allowance holds only when the load is 55 A or less. A subpanel whose load calculation reaches 60 A needs 4 AWG NM-B or 6 AWG THHN in conduit.
Bonding the neutral in the subpanel
At a subpanel the neutral bar must float. Leaving the bonding screw or strap in place puts neutral current on the enclosure, conduit and grounding conductors.
Skipping the spa disconnect
A hot tub needs a disconnect within sight, at least 5 ft from the tub. A GFCI breaker in the main panel does not satisfy this on its own when the panel is out of sight.
Ignoring the 75 °C terminal rating
6 AWG copper is a 60 A conductor only with 75 °C terminations. If either end is marked 60 °C, the conductor is treated as a 55 A wire.
Frequently asked questions
Is 6 gauge wire good for 60 amps?
As THHN or THWN-2 in conduit with 75 °C terminations, yes: 6 AWG copper is rated 65 A. As NM-B, it is rated 55 A and may sit on a 60 A breaker only under the next-size-up rule with a load of 55 A or less.
What size wire is needed for a 60 amp subpanel?
6 AWG copper or 4 AWG aluminum, with 75 °C terminations, is the minimum for a 60 A feeder; 4 AWG copper is the NM-B equivalent. Long runs may need a larger size for voltage drop.
What size wire is used for a hot tub on a 60 amp breaker?
Most 60 A hot tub circuits use 6 AWG copper THWN-2 in conduit, with a GFCI-protected spa disconnect within sight of the tub. The manufacturer's manual gives the required breaker and conductors.
Can 4 gauge aluminum wire be used for 60 amps?
Yes. 4 AWG aluminum is rated 65 A in the 75 °C column, which suits a 60 A breaker when the terminals are rated for aluminum and 75 °C.
What size wire does a 48 amp EV charger need?
A 48 A charger needs a 60 A circuit after the 125% continuous-load factor, wired with 6 AWG copper in conduit with 75 °C terminations or 4 AWG copper NM-B.