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Hot tub electrical installation.
Most hot tubs need a dedicated supply from the house. Get it right and the tub is safe and reliable; get it wrong and it trips, overheats or worse.
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What the supply involves
| Tub | Typical supply | What to check |
|---|---|---|
| Small plug-in (“13 amp”) tubs | An RCD-protected outdoor socket | The heater often cannot run with the pump on high |
| Most hard-wired tubs | A dedicated 16 A or 32 A circuit | The manufacturer’s spec decides the rating |
| Larger tubs and swim spas | 32 A or more, sometimes two supplies | Whether the house supply can take the load |
- 30 mA RCD protection on the circuit.
- A local isolator so the tub can be switched off for maintenance, placed where the manufacturer says, out of reach of anyone in the water.
- Armoured cable buried or ducted from the house, sized for the load and the distance.
- Notification: a new outdoor circuit is notifiable under Part P in England. We certify and notify it.
Before you buy the tub
- Send us the model so we can check its electrical spec.
- Check the consumer unit has a spare way and the incoming supply can take the extra load. Older boards may need upgrading.
- Decide where it goes, with a clear cable route from the house and somewhere for the isolator.
Photographs: a private residence in Totteridge (a project led by our director Michael Simm and now maintained by SEGplc) and new-build houses in Radlett.
Questions we’re asked
Can a hot tub be plugged into a normal socket?
Only small tubs designed for it, on an RCD-protected outdoor socket. Most hard-wired tubs need a dedicated 16 A or 32 A circuit.
How far from the tub should the isolator be?
Out of reach of anyone in the water, where the manufacturer specifies. Many specify a minimum distance; we follow the instructions for your tub.
Will I need a new consumer unit?
Sometimes. If the board has no spare way or no suitable RCD protection, it may need upgrading. We check on survey.
Written by SEGplc. Last updated 19 October 2026.
Need it done by a date?
Tell us the deadline. We’ll tell you honestly whether we can hit it — and we usually can.