Most hot tubs sold in the UK need a dedicated 32A electrical circuit. That is not a sales formality or an installer preference. It is a safety and performance requirement built into the tub itself. This guide explains what both types of supply look like, what an electrician actually does, what it costs, and where the lines are.
Two types of supply
Hot tubs run on one of two electrical setups: a standard 13A plug-and-play connection, or a dedicated 32A hardwired circuit. The difference matters more than most buyers expect.
13A plug-and-play
A plug-and-play tub connects to a standard 3-pin plug via a weatherproof outdoor socket. No rewiring, no consumer unit work, no electrician needed beyond confirming the outdoor socket is safe and correctly rated.
This works well for a specific type of buyer. Renters who cannot make structural changes to the property. People who want a small tub in a garden that already has a suitable outdoor socket. Buyers who are trialling hot tub ownership before committing to a larger model.
The trade-off is real. A 13A supply limits the heater to roughly 1.5kW to 2kW. That means slower heating, often twelve to twenty-four hours to reach temperature from cold. It also limits pump performance, so you will not get full jet power from a plug-and-play tub. Most plug-and-play models are compact, four-seater tubs by design. Manufacturers build them around the supply, not the other way round.
If you know you want a plug-and-play tub, make sure your outdoor socket is properly installed, IP-rated for outdoor use, protected by an RCD, and positioned at least two metres from the tub. A socket bolted to the garden wall that has been there for fifteen years may not meet current standards. Worth checking before the tub arrives.
32A hardwired
Most hot tubs, including every model in the VitaSpa and Reef Spas ranges, need a 32A dedicated circuit. This is a separate cable run from the consumer unit, protected by its own circuit breaker and RCD, terminating at a lockable outdoor isolator switch within sight of the tub.
The reason is straightforward. A full-size hot tub typically runs a 3kW heater alongside two or three pumps drawing additional current. The total load during a heating cycle easily exceeds what a 13A circuit can handle safely. A 32A circuit is sized to carry that load continuously without tripping, overheating cable, or causing a fault.
Three-phase supply (400V) is occasionally relevant for large swim spas or commercial installations. For a domestic hot tub in a Hampshire garden, you will almost certainly not need it. If a supplier tells you otherwise, ask them to show you the spec sheet.
What an electrician actually does
This is the practical bit most buyers have no visibility of until it is happening in their garden.
- The electrician identifies a suitable spare way in the consumer unit and fits the correct MCB and RCD protection for a 32A outdoor circuit.
- They run a suitably rated SWA (steel wire armoured) cable from the consumer unit to the installation location. This is typically buried in conduit or run along a wall. The route determines how long the job takes.
- An outdoor isolator switch is fitted within line of sight of the tub. This allows anyone near the tub to cut power immediately if needed. It is not optional, it is a Part P requirement.
- The circuit is tested, a test certificate is issued, and the work is notified to building control under Part P of the Building Regulations.
Safety note: All fixed electrical work outdoors, including hot tub supplies, falls under Part P of the Building Regulations. This means the work must be carried out by a registered electrician (typically NICEIC or NAPIT registered) or notified to building control and inspected before the installation is signed off. The test certificate is not bureaucracy. It is the document that confirms the circuit is safe, and you will need it if you ever sell the house.
Can I do it myself?
No. This is not a grey area.
Under Part P of the Building Regulations, any new circuit outdoors must be carried out by a competent registered electrician, or notified to building control and certified. DIY wiring of a hot tub supply is not legal, not insurable, and not safe. If there is ever a fault and your insurance investigator finds the circuit was not certified, you will not have a claim.
This applies even if you are confident with basic electrics. A 32A outdoor circuit buried in a garden, terminating at water, is not the same job as fitting a new socket in a kitchen.
Common mistakes
These come up more often than they should.
- Running an extension lead. An extension lead is not rated for continuous outdoor use or for the sustained load of a hot tub heater. This is a fire risk, not just a performance issue.
- Running a cable through a window or door. The cable is pinched, the door cannot seal, moisture gets in. No.
- Using underrated cable. A 2.5mm cable where a 6mm or 10mm is required will overheat under load. Cable rating must match the circuit and the run length.
- Skipping the RCD. A residual current device is not optional on an outdoor circuit near water. It is the protection that cuts power in milliseconds if there is a fault.
- Assuming the outdoor socket will do. A plug-and-play tub needs a socket that meets current outdoor standards. An old socket that was fine for garden lighting is not necessarily fine for a tub drawing 2kW continuously.
What does electrical work cost?
For a straightforward 32A circuit in a typical Hampshire garden, expect to pay between £300 and £600. The main variable is the cable run. A consumer unit on the back wall of the house, ten metres from the tub location, is a simpler job than a run of thirty metres around the side of the property with a road crossing.
If the consumer unit is already at capacity, there may be an additional cost to upgrade it or fit a sub-board. Your electrician will tell you this at the quote stage. It is not common, but it happens.
The test certificate and Part P notification are included in any reputable electrician’s quote. If someone offers to skip that step for a cheaper price, walk away.
How we handle it
When you buy a hot tub from us, Alex coordinates the electrical side as part of the install process. We can recommend a local registered electrician who has done this work before and knows what a hot tub circuit needs. They come out ahead of or on the day of installation, so the supply is live and certified when the tub is ready to fill.
You do not need to source an electrician independently or brief them on what a hot tub supply requires. We handle that conversation. If you already have an electrician you use and trust, that is fine too. We will make sure they have the spec they need.
If you are not sure whether your property is suitable for a 32A circuit, or you want to know what a cable run to your proposed tub location would involve, come into the showroom or give us a call. We can usually give you a good sense of what is involved before you commit to anything.