Hot Tub Electrical Installation Guidelines: UK Requirements

Which supply does your hot tub need?

Plug-in hot tubs come with a standard 13 A plug. Larger tubs are hard-wired to a 32 A or 40 A supply.³ The rating plate and manual for your model give the exact figure, and your electrician plans the whole route from it.

A plug-in tub still needs the right socket: a single outdoor-rated socket at least 2 m from the edge of the tub, on a circuit protected by a 30 mA RCD.³² If you are still choosing a tub, our guide to what to consider when buying a hot tub covers size and seating, and you can browse all hot tubs to see each model's power supply.

A dedicated circuit with a 30 mA RCD

The supply to a hot tub should be protected by a 30 mA RCD.²¹ It switches the power off if current starts to leak to earth, which is what protects you in wet, barefoot conditions.

Larger tubs get a dedicated circuit with no other appliances or sockets sharing it, and a breaker rated to the tub's maximum draw with room for the pumps' start-up surge. A tub drawing 30 A, for example, takes a 32 A breaker.⁵

When the new circuit joins an existing installation, your electrician checks that the consumer unit, the supply and the existing earthing and bonding are right for the extra load.² They also look at your earthing arrangement and whether supplementary bonding or an earth electrode suits your garden.¹

The cable route across the garden

For a hot tub outdoors, the IET recommends applying Section 702 of BS 7671, the section for swimming pools and other basins.² Its main point for the cable is protection along the whole route: armoured cable or a suitable enclosure, never loose cable laid in the soil or clipped to a fence.²

Buried cable goes at least 500 mm below the lowest local ground level, with marker tape about 150 mm below the surface, and the route is recorded on a drawing.² Our manuals suggest ducting (PC pipe) below ground or SWA cable.⁵

Ground levels change when a patio is laid or a lawn is lowered, so the finished level is agreed before the cable goes in. Running it round the edge of the plot keeps it clear of future digging.² Your electrician sizes the cable from the tub's rating, the length of the run and how it is installed.

The isolator beside your tub

An isolator is the switch that disconnects the tub from the mains for servicing. Manuals ask for an all-pole disconnection device in an accessible place close to the tub.⁵ The IET places it outside zone 1, 2 m from the edge of the tub, so it cannot be touched from inside the water.¹

Fix the tub's final position first, then measure out the 2 m. Equipment near the tub is chosen for splashes: at least IPX4, or IPX5 where water jets or hosing can reach it.¹ Fixed wiring is the preferred way to connect the tub, which prevents a socket being misused.¹

Keep every connection waterproof and the tub on its own supply: no extension leads, and no other device wired to it.⁵ Putting the tub in a room instead? Bathroom rules (Section 701) apply,¹ and our indoor or outdoor hot tub guide covers the room. Safety in and around the water is in our hot tub safety guide.

Electrician, Part P and your certificate

In England, a new circuit is notifiable work under Part P of the Building Regulations. It is certified by a registered competent person, a registered third-party certifier, or building control.⁴² Wales and Scotland have their own building rules, and a registered electrician will know the ones that apply to you.²

The electrician inspects and tests the work to BS 7671 and gives you an Electrical Installation Certificate.² Keep it with your tub paperwork.

Our tub manuals ask for a qualified electrician to make all electrical connections, and damage caused by incorrect amperage sits outside the warranty.⁵ Having the supply and isolator in place before delivery day means the final connection is quick.