What Size Electric Wire for a Hot Tub?

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Using the correct size wire is important when connecting a hot tub.
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Wires are electrical conductors that transfer electricity from a power source to an electrical device. They come in different sizes or gauges, materials and colors that refer to their intended function. Choosing the correct wire for a hot tub ensure a safe, energy efficient usage and increase the lifespan of your equipment. When in doubt, consult a licensed electrician with experience hooking up hot tubs.


Wire Size

Wire size or gauge is determined by a measure referred to as the American wire gauge number. This number refers to its thickness and ability to handle certainly volume and current pressures measured in amps and volts. The higher the AWG number, the thinner the wire. Check with the manufacturer or consult to user's manual to determine the correct wire gauge, it can differ by spa model. You may use a wire with an AWG number that is lower than the required gauge, but never one that is higher. Thick wires can handle lighter loads, but thin wires cannot heavier loads. Check the circuit breaker to make sure you are using a wire with a corresponding AWG number.


Wire Length

Wire length is also an important consideration when connecting a hot tub. In general, it is best to keep the distance between the hot tub and the ground fault circuit interrupter breaker as short as possible. This reduces the chance of ground faults that may trip the GFCI breaker due to moisture buildup in the conduit. Use a wire with a lower AWG number if the hot tub is far from the GFCI breaker.

Wire Material and Color

Copper is the preferred wire material for hot tubs. Avoid using aluminum or copper-coated aluminum wires, which are less efficient. Use a solid rather than a stranded wire because solid wires are less resistant. If your hot tub uses a four-wire system, which is the most common these days, you need a green ground wire, black and red hot wires, and a white neutral wire. Three-wire systems do not use a white neutral wire.



Connecting a hot tub is a risky and challenging process. Only electricians and those with ample experience should connect hot tubs themselves. If you do connect the hot tub yourself, hire an electrician to test the system before use. Don't install a hot tub under active power lines or within 10 feet of outdoor lighting. Check the GFCI breaker device frequently by pressing the "TEST" button. Never connect a four-wire hot tub to a three-wire circuit.