6 AWG Wire Amp Rating: How Many Amps Can 6 Gauge Wire Carry?
Short answer
Under NEC Table 310.16, 6 AWG copper wire is rated 55 amps at 60°C, 65 amps at 75°C and 75 amps at 90°C. In a home, 6/2 or 6/3 NM-B (Romex) is limited to the 60°C column, so it is a 55 amp cable that normally goes on a 50 amp breaker. 6 AWG THHN copper in conduit with 75°C terminals is good for 65 amps and a 60 amp breaker. 6 AWG aluminum is rated 50 amps at 75°C.
Six gauge feeds 50 amp ranges, hot tubs, welders, EV chargers and small subpanels. It is also confusing, because the 6 gauge wire amp rating changes with the insulation type, the cable type, the terminals on the breaker and the conditions around the run. The same copper conductor can be a 55, 65 or 75 amp wire depending on which rule applies.
Below is the full 6 AWG ampacity chart, the breaker sizes it can protect, derating, voltage drop and solar use. Values come from Table 310.16 and Table 310.17 in NFPA 70, the National Electrical Code.
6 AWG wire ampacity chart
Ampacity is the current a conductor can carry continuously without going over its temperature rating. The first three rows assume no more than three current-carrying conductors in a raceway or cable and an ambient temperature of 86°F (30°C). The free air rows are for single conductors not in a raceway, such as PV wire on a rooftop rack.
| 6 AWG conductor | 60°C (140°F) | 75°C (167°F) | 90°C (194°F) |
|---|---|---|---|
| Copper, raceway or cable (310.16) | 55 A | 65 A | 75 A |
| Aluminum, raceway or cable (310.16) | 40 A | 50 A | 55 A |
| Copper, single conductor in free air (310.17) | 80 A | 95 A | 105 A |
| Aluminum, single conductor in free air (310.17) | 60 A | 75 A | 80 A |
The copper figures match wire makers’ published tables, including the Cerrowire ampacity chart. Solid and stranded 6 AWG share the same rating.
Which 6 AWG rating applies to you?
A circuit is only as good as its weakest part: the insulation, the cable type or the terminals at each end. Here is how the common cases work out:
- 6/2 or 6/3 NM-B (Romex): Section 334.80 limits NM cable to the 60°C ampacity, so it is a 55 amp cable even though the individual conductors have 90°C insulation. UF-B cable follows the same 60°C limit.
- 6 AWG THHN or THWN-2 copper in conduit: Section 110.14(C) lets you use the 75°C column when the breaker and the equipment lugs are both marked 75°C, which almost all modern gear is. That makes it a 65 amp conductor.
- The 90°C value of 75 amps is a starting point for derating only. You can apply correction factors to 75 A, but the result can never exceed the 75°C termination rating of 65 A.
- 6 AWG aluminum (often found in SER cable or as a feeder in conduit) is a 50 amp conductor at 75°C. See the full aluminum wire ampacity chart for the larger sizes.
What breaker size goes with 6 gauge wire?
Section 240.4 says the breaker must protect the conductor at its ampacity. Section 240.4(B) allows rounding up to the next standard breaker size when the ampacity falls between sizes, the breaker is 800 A or less, and the circuit does not feed multiple receptacles for cord-and-plug loads. The pairings below are the conservative ones most electricians use.
| Wire type | Ampacity | Usual breaker | Typical loads |
|---|---|---|---|
| 6/2 or 6/3 NM-B copper | 55 A | 50 A | Range, cooktop, hot tub, 40 A EV charger |
| 6 AWG THHN copper, 75°C terminals | 65 A | 60 A | 48 A EV charger, 60 A subpanel, welder |
| 6 AWG aluminum, 75°C terminals | 50 A | 50 A | 50 A feeder to a shed or garage |
For comparison, 8 AWG copper is rated 40, 50 and 55 amps and 4 AWG copper 70, 85 and 95 amps. At the edge, step up a size. For the smaller circuits, see what size wire a 40 amp breaker needs.
How many watts can 6 AWG wire carry?
Power is volts times amps, so the wattage limit depends on the circuit voltage. Using the 80% guideline for continuous loads keeps you inside the rating.
6/3 NM-B on a 50 A breaker at 240 V: 240 × 50 = 12,000 W maximum, 240 × 40 = 9,600 W continuous
6 THHN on a 60 A breaker at 240 V: 240 × 60 = 14,400 W maximum, 240 × 48 = 11,520 W continuous
At the raw table ampacity, 6 AWG copper carries 13,200 W at 55 A, 15,600 W at 65 A and 18,000 W at 75 A on a 240 V circuit. Run your own appliance numbers through the amps to watts calculator.
Worked example: 6 gauge wire for an EV charger
EV charging is a continuous load, so Section 625.41 requires the circuit to be sized at 125% of the charger’s output. That single rule decides whether 6 gauge NM-B is enough.
40 A charger: 40 × 1.25 = 50 A, so a 50 A breaker and 6/2 NM-B (55 A) work
48 A charger: 48 × 1.25 = 60 A, so a 60 A breaker and 6 THHN in conduit (65 A) work, but 6 NM-B (55 A) does not
That is why installers often set a 48 A charger to 40 A on existing 6/2 NM-B. A 40 A charger delivers about 9.6 kW, or roughly 25 to 30 miles of range per hour. Check the time for your car and battery with the EV charging time calculator.
Derating 6 AWG for heat and crowded conduit
Table values assume 86°F and three or fewer current-carrying conductors. Crowded conduit or a hot attic lowers the allowed current. You start from the 90°C column for THHN and apply the factors from Section 310.15.
| Condition (6 AWG copper THHN, 90°C base 75 A) | Factor | Adjusted ampacity |
|---|---|---|
| 4 to 6 current-carrying conductors in one conduit | 0.80 | 60 A |
| 7 to 9 current-carrying conductors | 0.70 | 52.5 A |
| Ambient 97°F to 104°F (36°C to 40°C) | 0.91 | 68.25 A, capped at 65 A |
| Ambient 106°F to 113°F (41°C to 45°C) | 0.87 | 65.25 A, capped at 65 A |
| 106°F to 113°F and 4 to 6 conductors | 0.87 × 0.80 | 52.2 A |
Even when derating leaves you above 65 A, the 75°C lug still caps the circuit at 65 A. If the derated number drops below the breaker size, move up to 4 AWG.
Voltage drop on long 6 gauge runs
Ampacity ignores the voltage lost over distance. The NEC suggests, in an informational note, keeping branch circuit drop to about 3%. Using the resistance of uncoated 6 AWG copper from NEC Chapter 9, Table 8 (0.491 ohms per 1,000 feet), a 240 V circuit looks like this:
| One-way distance | 30 A load | 40 A load | 48 A load |
|---|---|---|---|
| 50 ft | 1.5 V (0.6%) | 2.0 V (0.8%) | 2.4 V (1.0%) |
| 100 ft | 2.9 V (1.2%) | 3.9 V (1.6%) | 4.7 V (2.0%) |
| 150 ft | 4.4 V (1.8%) | 5.9 V (2.5%) | 7.1 V (2.9%) |
| 200 ft | 5.9 V (2.5%) | 7.9 V (3.3%) | 9.4 V (3.9%) |
Example: 2 × 100 ft × 48 A × 0.000491 Ω/ft = 4.7 V, or 2.0% of 240 V
At 240 V, 6 AWG copper stays under 3% up to about 183 feet at 40 A and about 153 feet at 48 A. Past that, go to 4 AWG. Enter your own distance in the voltage drop calculator, or let the wire size calculator pick a gauge for both ampacity and drop.
6 AWG wire in solar and 12 V battery systems
In a low-voltage DC system, voltage drop usually limits 6 gauge long before ampacity does. A 50 A charge controller output running 20 feet one way to a 12 V battery bank on 6 AWG copper loses 2 × 20 × 50 × 0.000491 = 0.98 V. That is about 8% of 12 V, far more than the 2% to 3% most installers aim for on battery cables. The same run at 48 V loses about 2%, which is fine.
On the PV side, 6 AWG PV wire or USE-2 run as single conductors in free air is rated 95 A at 75°C and 105 A at 90°C, but solar circuits carry their own sizing rules. Section 690.8 sizes PV source circuits at 125% of the panels’ short circuit current, then another 125% for continuous duty. The solar cable size calculator applies those factors and voltage drop together, and the solar fuse size calculator matches the overcurrent protection.
Installation tips for 6 gauge circuits
- Match the terminal rating. Use the 75°C column only when both ends are marked 75°C. Older equipment marked 60°C, or unmarked, drops 6 AWG copper to 55 A.
- Torque every lug to the value printed on the breaker or device. Section 110.14(D) requires a calibrated torque tool where a value is marked.
- Use AL-rated lugs for aluminum. Never use NM-B in wet locations; use UF-B or THWN-2 in conduit outdoors.
- Pull a permit. A 50 or 60 amp circuit is permit work in most US jurisdictions. Hire a licensed electrician if any step is unclear.
Frequently asked questions
How many amps can 6 gauge wire carry?
6 AWG copper is rated 55 amps at 60°C, 65 amps at 75°C and 75 amps at 90°C under NEC Table 310.16. In practice, 6 gauge NM-B cable is a 55 amp cable and 6 AWG THHN in conduit with 75°C terminals is a 65 amp conductor.
Can I use 6 gauge wire on a 60 amp breaker?
Yes with 6 AWG copper THHN or THWN in conduit and 75°C rated terminals, because it is rated 65 amps. With 6/2 or 6/3 NM-B the cable is limited to 55 amps, so a 50 amp breaker is the standard choice unless your inspector accepts the next size up rule in Section 240.4(B) for that load.
Is 6/3 Romex good for 60 amps?
Not for a continuous load such as a 48 amp EV charger, which needs at least 60 amps of conductor ampacity. 6/3 NM-B is rated 55 amps at the 60°C column. Use 4/3 NM-B or 6 AWG THHN in conduit for a full 60 amp circuit.
How many amps can 6 AWG aluminum wire carry?
6 AWG aluminum is rated 40 amps at 60°C, 50 amps at 75°C and 55 amps at 90°C. With 75°C terminals marked for aluminum, it is used as a 50 amp conductor, which is roughly what 8 AWG copper carries.
How far can I run 6 gauge wire?
On a 240 V circuit, 6 AWG copper keeps voltage drop under 3% up to about 244 feet at 30 amps, 183 feet at 40 amps and 153 feet at 48 amps. On a 120 V circuit the distances are half as long. For longer runs, step up to 4 AWG.
