The hot tub arrives on a pallet on Friday, the family wants it bubbling by Saturday, and the delivery driver cheerfully points out that the electrics are your problem. Hot tub electrical installation is the part of the purchase most buyers never price in, and it is the part that decides whether your new spa is safe. A 13 amp plug-and-play model and a 32 amp hard-wired tub have completely different requirements, and getting them wrong can trip your whole house or worse. Here is what a qualified electrician actually does, and what it costs in June 2026.

Why a hot tub electrical installation needs its own circuit

Most full-size tubs draw between 13 and 40 amps when the heater and pumps run together. That is more than a kettle, a washing machine, and a tumble dryer combined, running for hours at a time. Sharing a circuit with anything else means nuisance tripping at best and overheated cable at worst.

A proper installation runs steel wire armoured cable from your consumer unit to a dedicated outdoor rotary isolator beside the tub. The circuit gets its own breaker and 30 mA RCD protection, sized to the manufacturer’s stated load. Our domestic electrical services team sizes the cable for the route length too, because a long garden run on undersized cable loses voltage and cooks the insulation.

Plug-and-play tubs sold as 13 amp models still deserve respect. They should run from a single dedicated socket, never an extension lead, and that socket needs RCD protection. The garden electrics guidance from Electrical Safety First is blunt about extension leads and water: do not mix them.

One more detail buyers miss: the RCD type. Modern tub control packs use variable speed pumps whose electronics can leak small DC currents, and a standard Type AC device may not detect them. Most manufacturers now specify a Type A or Type B RCD in their installation manuals, and an installer who has not read that page is telling you something about the rest of the job.

The regulations: Part P, BS 7671, and why notification matters

Outdoor electrical work in England falls under Building Regulations. Approved Document P makes new circuits in a garden notifiable work, which means the job must either be signed off by a registered electrician or inspected by building control. A registered installer self-certifies and issues the certificate, which is the cheaper and faster route.

BS 7671 adds the technical detail: zones around the water where equipment is restricted, minimum distances for sockets and switches, and mandatory RCD protection for outdoor circuits. An unregistered installation with no certificate shows up the moment you sell the house or make an insurance claim. Buyers’ solicitors now routinely ask for electrical certificates, so a missing one costs real money later.

What it costs in 2026

For a typical North West garden, a hard-wired hot tub supply sits between £450 and £900 fitted. The spread comes from cable route length, whether the cable can be clipped to a wall or has to be buried in trench, and the state of your consumer unit. If the board is full or has no spare RCD-protected way, allow another £150 to £300 for a new circuit module or a small board upgrade.

Trenching is the hidden cost. Buried armoured cable should sit at least 450 mm deep with warning tape above it, and digging that across a patio costs more than crossing a lawn. Some customers combine the trench with new garden lighting circuits so one excavation serves two jobs. That single decision often saves £200 or more.

Timing is worth a thought too. Tub retailers run their biggest promotions in May and June, which means electricians’ diaries fill with supply work in exactly those weeks. Booking the electrical survey before the tub is even ordered usually means the circuit is ready the day the crane arrives, rather than the tub sitting empty on the patio for a fortnight.

Getting an older property hot tub ready

Houses wired before the mid 2000s often have consumer units with no spare capacity and no RCD protection at all. Before quoting a tub supply on an older property, a good electrician checks the earthing arrangement, the main fuse rating, and the condition of the existing board. A 60 amp main fuse with electric heating already on it may not have headroom for a 32 amp tub.

If your wiring has never been formally tested, booking an EICR inspection before the tub arrives is the sensible order of work. It costs from around £140 for a typical three-bedroom semi and tells you exactly what the installation can support. Finding out the board needs replacing after the tub is sat full of water is the expensive version of the same conversation.

Mistakes that delay the first soak

The most common mistake is ordering the tub before anyone has looked at the electrics. Delivery dates are fixed by the retailer, electrical surveys are not, and the two need to happen in the right order. A ten-minute phone call with a photo of your consumer unit settles most of the questions before any money changes hands.

Next is placing the tub before thinking about the isolator. The switch must be within sight of the water but out of the splash zones, and a tub pushed hard against a fence can leave nowhere compliant to mount it. Agree the final position with both the spa supplier and the electrician before the base is laid.

The third is treating the crane day as the deadline for everything. Cable routes, trenching, and consumer unit work can all be finished a week early, leaving only the final connection and testing for delivery day. Sequencing the work that way costs nothing and removes the single biggest cause of a tub sitting empty into July.

Frequently Asked Questions