NEC Wire Sizing
What Size Wire for a Hot Tub?
The breaker, copper and aluminum wire, and ground for a typical hot tub circuit, with the NEC basis and the nameplate caveats that actually decide it.
Hot Tub Circuit Spec
| Voltage | 240V |
| Breaker | 50A GFCI |
| Copper wire | #6 |
| Copper (75°C conduit) | #8 |
| Aluminum wire (75°C, SER or conduit) | #6 |
| Equipment ground (Cu) | #10 |
Portable spas and hot tubs are commonly on a 50A GFCI circuit, but the nameplate rules: some are 40A and some 60A. NEC Article 680 requires GFCI protection and a disconnect within sight and at least 5 feet from the tub. Wire sized at NEC Table 310.16 (copper lead at the 60°C column for NM-B); ground per NEC Table 250.122. The appliance nameplate lists the exact minimum circuit and maximum breaker; it always governs over a typical value.
Aluminum branch conductors are 75°C-rated AA-8000 alloy (SER cable, or XHHW-2 / THWN-2 in conduit); there is no 60°C aluminum NM-B, so the aluminum row uses the 75°C column. Where the terminations are rated 60°C only, size aluminum from the 60°C column instead (#4 here).
Adding this as a new load? Check whether your panel can handle it (the NEC 220.87 service check), or compare it against the breaker size by load chart.
Long Run? Size It Exactly
For a long run where voltage drop matters, or a nameplate that differs from the typical value, enter your exact load, distance, and conditions.
Frequently Asked Questions
What size wire do I need for a hot tub?
A hot tub typically uses a 50A / 240V circuit, which calls for #6 copper (or #6 aluminum) conductors and a #10 copper equipment ground per NEC Table 250.122. That is the 60C column, the NEC default for NM-B cable and terminations 100A and under; on 75C-rated terminals in conduit you may use #8 copper. Portable spas and hot tubs are commonly on a 50A GFCI circuit, but the nameplate rules: some are 40A and some 60A. NEC Article 680 requires GFCI protection and a disconnect within sight and at least 5 feet from the tub.
What size breaker for a hot tub?
A 50A double-pole (240V) breaker. The #6 copper conductors are matched to that 50A rating, and it must be a GFCI breaker (or GFCI protection ahead of the appliance). Do not oversize the breaker to a wire it does not protect: the breaker and the conductor go up together. Always confirm against the appliance nameplate, which lists the exact minimum circuit and maximum overcurrent device.
Does a hot tub need GFCI protection?
Yes. Current NEC requires GFCI protection for this appliance (NEC 680.44 and 210.8). Use a GFCI breaker or a GFCI device ahead of it. For a hot tub or spa, a disconnect within sight and at least 5 feet away is also required (NEC 680).
Can I use aluminum wire for a hot tub?
Yes. On the 75C column (the usual basis for aluminum), a 50A circuit needs #6 aluminum, versus #8 copper. Aluminum is common on larger circuits and services to save cost; apply antioxidant to the terminations, torque to the listed spec, and remember aluminum drops slightly more voltage on long runs.
Wire Size for Other Appliances
Electric Dryer
#10 copper on a 30A / 240V circuit.
Electric Range
#6 copper on a 50A / 240V circuit.
Electric Wall Oven
#8 copper on a 40A / 240V circuit.
Electric Cooktop
#8 copper on a 40A / 240V circuit.
Electric Water Heater
#10 copper on a 30A / 240V circuit.
Dishwasher
#12 copper on a 20A / 120V circuit.
Garbage Disposal
#14 copper on a 15A / 120V circuit.
Built-In Microwave
#12 copper on a 20A / 120V circuit.
Refrigerator
#12 copper on a 20A / 120V circuit.
Freezer
#12 copper on a 20A / 120V circuit.
Garage Door Opener
#12 copper on a 20A / 120V circuit.
Wire Size Calculator
Full NEC 310.16 sizing for any load, distance, and conditions.