Plug-and-play Lay-Z-Spas through to hardwired 40A spas with sub-boards. Weatherproof IP-rated isolators within sight of the tub, SWA cable for buried runs, 30mA Type A or Type B RCBO on every circuit, supplementary bonding where required. From £180 + VAT @ 20%.
07889 334849 · Dan Stevens
NAPIT
CHAS
City & Guilds
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Part P
BS 7671Section 702 of BS 7671 governs swimming pools, paddling pools, hot tubs and whirlpools because the user is sitting in conductive water with reduced body resistance. Three things matter most: the supply circuit (sized to the spa label), the isolator (weatherproof, within sight of the tub), and supplementary bonding to any extraneous metalwork. Get those right and the install is safe, certified and warranty-friendly.
Plug-and-play tubs run from a 13A radial. Hardwired spas range from 16A through 40A depending on heater rating and pump count. Cable usually 6mm² minimum, 10mm² for long runs or 40A circuits.
Every hot tub circuit must have 30mA RCD protection. Type A handles the AC plus pulsating DC fault currents typical of modern spa pumps. Type B is needed if the spa has a variable-speed drive that produces smooth DC.
An accessible IP-rated rotary isolator within sight of the hot tub so anyone can cut supply fast. Mounted on a nearby wall, post or housing — close enough to be useful, far enough to be out of splash. Lockable, labelled.
Real DS Electrical install — weatherproof IP-rated outdoor accessory, the standard we apply to every hot tub feed.
No corner-cutting. Whether it’s a 13A weekend Lay-Z-Spa feed or a hardwired 40A install with sub-board, the standard is the same. Sized to the spa label, weatherproof isolator within sight, SWA where it goes underground, RCBO of the correct type and rating, supplementary bonding where required, certificate emailed before we leave.
We read the spa rating plate on site — current draw, voltage, RCD type required — and size the circuit and cable to that, not to a guess. No undersizing, no oversizing.
If the cable is going underground, it goes in steel-wire-armoured cable at correct depth on warning tape, glanded both ends. T&E in conduit is not adequate for permanent buried runs.
IP65 or IP66 rotary isolator within sight of the tub, lockable for service isolation, clearly labelled, sited out of splash range. Compliant with Section 702.
Type A as default for spas with simple inverter pumps. Type B where a variable-speed drive produces smooth DC fault currents. We choose, not guess.
Assessed against Section 702 on the day — bonding to handrails, metal pipework, heater body where required. Documented on the EIC.
Electrical Installation Certificate, NAPIT Part P notification lodged with Building Control. Paperwork in your inbox before we leave site.
Final price depends on cable run length, whether it’s a surface or buried run, ground conditions, the spa rating and whether existing consumer unit capacity is available. Survey is free; written quote is fixed. Read the disclaimer below the cards before assuming.
Hot tubs sit alongside garden rooms, outdoor sockets, EV chargers and outside lighting — everything outside needs the same disciplined approach. IP rating to suit exposure, SWA underground, isolation that works in the rain, terminations that don’t corrode. We do all of it across Wells, Bath, Frome and the surrounding villages.
Only if the manufacturer explicitly says it’s a 13A plug-and-play model (most Lay-Z-Spa and other inflatable tubs are). Even then it should be on a dedicated weatherproof IP-rated outdoor socket, on its own RCD-protected circuit — not a daisy-chain off an extension lead, which is the single most common cause of tripping and burnt plug-tops we get called to. Anything bigger than a small inflatable is hardwired only.
Section 702 covers swimming pools, paddling pools and the basins of fountains, plus locations containing them — and BS 7671 explicitly extends similar special-location thinking to hot tubs and whirlpools. Practical implications: 30mA RCD on every circuit, IP-rated accessories, an isolator within sight of the tub so it can be killed without going back to the consumer unit, and supplementary equipotential bonding to any extraneous metalwork (handrails, metal pipework, the heater body) where applicable. We design every install to those requirements before we lift a screwdriver.
Read the spa label — it states the maximum current draw and required circuit size. Plug-and-play models = 13A radial. Most mid-size hardwired tubs (Marquis, Caldera entry models) = 16A or 32A on a 30mA RCBO. Larger spas with multiple pumps and 6kW heaters = 32A or 40A, often on a sub-board next to the tub. Cable size is usually 6mm² minimum from the consumer unit, going up to 10mm² for long runs or 40A circuits. We size the circuit and cable from the actual rating plate on the day of survey, never guess.
BS 7671 requires an accessible means of isolation within sight of the hot tub — typically a weatherproof IP65/IP66 rotary isolator on a nearby wall or post, ideally within 2–3 metres of the tub but not so close it’s in a splash zone. The point is that anyone in the tub can be cut off from supply quickly without somebody having to run back inside to find the consumer unit. We always fit a labelled, lockable IP-rated isolator and walk you through how to use it.
Type A as default — it handles AC plus pulsating DC fault currents, which covers most modern spa pumps. Type B is required if the spa has a variable-speed drive (VSD) pump that can produce smooth DC fault currents, because Type A devices can be blinded by smooth DC and fail to operate. Manufacturer documentation usually states the required type; if it doesn’t, we err towards Type B for high-end or VSD-equipped spas.
Yes. A new dedicated circuit for a hot tub is notifiable work under Part P. We notify automatically through our NAPIT registration — you do not need to apply separately. Every job ends with an Electrical Installation Certificate, plus the NAPIT compliance certificate logged on the national database. That paperwork is what the spa manufacturer’s warranty department, your home insurer and any future buyer’s surveyor will want to see.
Hot tubs always need the electrics ready before delivery day. Get the cable run, isolator and circuit booked in early — we’ll co-ordinate with the spa company. Free survey, fixed quote, NAPIT certified.
07889 334849