Sauna electrical installation: what to plan before the base
Most sauna problems start before the first session, in the cable between the house and the garden. A heater is a fixed appliance drawing tens of amps, and the supply has to be planned like one.
How much power a sauna needs
A 6 kW heater at 230 V draws about 26 A. An 8 kW heater draws about 35 A. Add lighting and a control panel and the figure rises slightly. That is well beyond a domestic socket circuit, which is usually 13 A in the UK or 15–20 A in North America.
What the installation involves
- A dedicated circuit from the consumer unit, sized for the heater.
- An isolator near the sauna, so the heater can be switched off locally.
- Correct cable for the run length and the load, usually armoured if it goes underground.
- RCD protection, given the wet environment.
- A qualified electrician to certify the work.
What to check before ordering
| Check | Why it matters |
|---|---|
| Available supply at the property | Older supplies may need an upgrade |
| Distance from the consumer unit | Long runs need thicker cable |
| Heater rating | Determines breaker and cable size |
| Local regulations | Garden buildings may need notification |
| Access for the cable route | Digging or drilling is easier before the base is built |
The cost of getting it wrong
An undersized cable overheats; an oversized breaker protects nothing. Both are expensive to fix after the base is laid and the sauna assembled. The cheapest moment to plan the supply is before the kit arrives.
Can a sauna run from a standard socket?
Small infrared cabins sometimes can, since panels draw less. Traditional heaters cannot. Check the rating on the specific model, not the category.
Frequently asked questions
Do I need a permit?
Depends on the country and the size of the building. Garden structures above a certain height or area often need notification; electrical work usually needs certification.
Can I install the heater myself?
In many places it is not permitted for a fixed high-power appliance. Even where it is, certification is usually required for insurance.
How long does installation take?
The electrical work is typically a day for a straightforward run, longer if a trench is needed.
What about a generator?
Possible, but the start-up load of a heater is heavy. Size the generator above the heater rating and check it can handle the surge.
Does the sauna need its own earth?
The installation must be earthed as part of the circuit. Your electrician will confirm the arrangement for the site.
The short version
Plan the supply before the base: dedicated circuit, correct cable, local isolator, RCD, and a certified installation. The heater is the last thing to buy, not the first.