Section 702 of BS 7671:2018+A4:2026 covers swimming pools, paddling pools and fountain basins, and by extension hot tubs. It defines three zones around the water: zone 0 is inside the basin, zone 1 runs 2 m horizontally from the rim and 2.5 m up, and zone 2 runs a further 1.5 m beyond zone 1. In zones 0 and 1 the only protective measure allowed is SELV at 12 V AC or 30 V DC or less, with the source outside all three zones. No socket-outlets or switchgear go in zones 0 or 1, everything in zone 2 needs 30 mA RCD, SELV or electrical separation, and all extraneous-conductive-parts in the zones need supplementary bonding.
- Zones: 0 is the water, 1 is 2 m from the rim (2.5 m high), 2 is a further 1.5 m. Zone 2 does not apply to fountains.
- Zones 0 and 1: SELV only, 12 V AC / 30 V DC maximum, source outside the zones. No sockets, no switches, no junction boxes (SELV excepted in zone 1).
- Zone 2: sockets and switches allowed only with SELV, electrical separation for one item, or 30 mA RCD.
- IP ratings: IPX8 in zone 0, IPX4 in zone 1 (IPX5 where water jets are used), IPX2 indoors or IPX4 outdoors in zone 2.
- Supplementary bonding of all extraneous-conductive-parts in zones 0, 1 and 2 to the protective conductors of equipment in those zones.
- A hot tub is a new circuit: EIC, Part P notification, and the manufacturer's instructions on RCD type and isolator position.
What does Section 702 actually cover?
Regulation 702.11 sets the scope: the basins of swimming pools, fountains and paddling pools, and the zones around them. It does not name hot tubs, spas or plunge pools. That gap catches people out, because the domestic job you are most likely to get is a plastic hot tub on a patio, not a tiled pool.
The accepted position, set out in IET Guidance Note 7 (Special Locations) and in Electrical Safety First's best practice guidance, is that a hot tub is a basin of water with people in it and so the Section 702 zones and protective measures are applied. BS 7671 backs that up in Regulation 134.1.1, which requires equipment to be installed in accordance with the manufacturer's instructions, and every hot tub manual on the market specifies a dedicated RCD-protected supply and an isolator a set distance from the tub.
Fountains are treated differently in a few places: zone 2 does not exist for fountains (702.32), and the rules on luminaires and pumps in fountain basins are their own subsection. This guide sticks to pools and hot tubs.
Where are zones 0, 1 and 2?
The zones are measured from the basin itself, not from the pump house or the plant room. Walls, fixed partitions and doors limit a zone in the same way they do in a bathroom under Section 701: if a solid wall stops you reaching from the water to a point, that point is outside the zone.
| Zone | Extent | Height | Typical contents |
|---|---|---|---|
| 0 | Interior of the basin, including the jet nozzles and any foot-wash basin | Water surface | Underwater luminaires, jets, SELV only |
| 1 | 2 m horizontally from the rim of the basin | 2.5 m above the floor or the surface people stand on | Steps, diving boards, rails, pumps built into the tub shell |
| 2 | 1.5 m beyond zone 1 (3.5 m from the rim in total) | 2.5 m above the floor | Isolators, sockets, lighting, heater plant |
Two details from Regulation 702.32 matter on a real job. First, the 2.5 m height in zone 1 is measured from the floor, but where there is a diving board, starting block, chute or slide, zone 1 extends 1.5 m around it and up to 2.5 m above the highest surface a person could stand on. Second, a pool on a raised deck or a hot tub sunk into decking still has its zones measured from the rim, so a sunken tub has zone 1 at deck level extending 2 m from the edge.
Compare this with the 0.6 m and 2.25 m limits of Section 701 bathroom zones (/guides/bathroom-zones-section-701) and you can see why pool jobs need more room: a 2 m by 2 m hot tub on a 4 m deep patio puts the whole patio and the back wall of the house in zone 1 or 2.
What protective measures are allowed in each zone?
Regulation 702.410.3.4 is the heart of the section.
In zones 0 and 1, the only permitted protective measure is SELV at a nominal voltage not exceeding 12 V AC or 30 V ripple-free DC, and the safety source must be outside zones 0, 1 and 2 (702.410.3.4.1). There is a specific allowance for fixed equipment designed for use in pools in zone 1, such as filter pumps and jet pumps, under 702.55.1 and 702.55.4, provided it is supplied through a circuit with 30 mA RCD protection and the equipment is inside an insulating enclosure of Class II or equivalent, or is separated from the pool by a fixed partition that cannot be removed without tools. That is what makes the built-in pump pack of a hot tub acceptable: it is designed for the location and is behind the tub's own panel.
In zone 2 (702.410.3.4.2) you can choose any one of SELV, electrical separation supplying one item of current-using equipment, or automatic disconnection of supply with additional protection by a 30 mA RCD. In practice that means a 30 mA RCD or RCBO on the circuit, and that is what you will see on nearly every job.
Outside the zones the general rules apply, but remember that an outdoor socket-outlet rated up to 32 A needs 30 mA RCD protection under Regulation 411.3.3 whatever zone it is in, and buried cables need RCD protection or earthed metallic covering under 522.6.204. Our garden socket guide (/guides/garden-and-outdoor-sockets-regulations) covers the outdoor rules in more depth.
Where can sockets, switches and junction boxes go?
Regulation 702.53 is blunt: in zones 0 and 1, no switchgear, controlgear or socket-outlet. Regulation 702.522.24 adds that junction boxes are not allowed in zones 0 and 1 either, except SELV boxes in zone 1.
Zone 2 allows socket-outlets, switches and accessories, but only with one of the three zone 2 protective measures above. For a small pool where zone 1 physically cannot be avoided, 702.53 does allow a socket-outlet or switch in zone 1 if it is outside arm's reach (at least 1.25 m) from the zone 0 boundary, at least 0.3 m above the floor, and protected by SELV, electrical separation or a 30 mA RCD. Treat that as the exception for a plant room that backs onto a plunge pool, not a licence to put a socket next to a hot tub.
For hot tubs, the isolator is the thing customers and inspectors both look at. Manufacturers typically ask for a rotary isolator or a switched fused connection unit at least 2 m from the tub, which lands it just outside zone 1 and inside zone 2, so it still needs to be on the RCD-protected circuit, and it must be weatherproof (IP44 minimum outdoors, IP65 or IP66 is normal for a rotary isolator on a wall). The user needs to be able to reach it without getting in the water, and the pump pack itself must not be the only means of isolation.
What IP ratings apply?
Regulation 702.512.2 sets the minimum ingress protection for equipment in each zone.
| Zone | Minimum IP rating | Note |
|---|---|---|
| 0 | IPX8 | Continuous immersion |
| 1 | IPX4 | IPX5 where water jets are used for cleaning |
| 2 | IPX2 indoors, IPX4 outdoors | IPX5 where water jets are used for cleaning |
Manufacturers' pump packs are usually tested to their own product standard rather than to IPX4, which is another reason the fixed-equipment exception in 702.55 leans on Class II construction and a fixed partition rather than an IP code. Outdoor lighting on a wall inside zone 2 needs IPX4 as a minimum; a bathroom IP44 downlight satisfies that, but its supply still needs to come from an RCD-protected circuit.
What bonding is required?
Regulation 702.415.2 requires supplementary equipotential bonding connecting all extraneous-conductive-parts in zones 0, 1 and 2 to the protective conductors of all exposed-conductive-parts of equipment in those zones. That is a wider net than a bathroom. It catches metal ladders, handrails, starting blocks, drain covers, metal grids in the floor, metallic pool liners and reinforcement, and the steel frame of a pool enclosure.
Two points on the practicalities. Regulation 702.415.2 note: for a pool with a reinforced concrete basin the reinforcing steel can be bonded via the metal grid it forms, and a reinforced floor around the pool may also count as an extraneous-conductive-part. And for a moulded acrylic hot tub on a wooden deck, there may be no extraneous-conductive-parts within the zones at all, in which case you record that no supplementary bonding was required and why. If there is a metal handrail bolted into a concrete plinth, bond it.
Main protective bonding at the origin is unaffected by any of this (/guides/what-is-main-protective-bonding). The 10 mm² main bonding for a PME supply is still needed, and the supplementary bonding conductor size follows Regulation 544.2: at least 2.5 mm² if mechanically protected, 4 mm² if not.
PME or TT for an outdoor hot tub?
Section 702 does not prohibit the use of a PME earth in the way Section 722 does for EV charging or Section 708 for caravans. Most domestic hot tubs on a PME supply are fed by SWA from the house consumer unit, with the armour as the CPC or a separate CPC inside the cable, and a 30 mA RCD upstream.
There is a body of opinion, reflected in IET guidance on outdoor installations, that where a person in the water can also touch true earth (a metal fence post, wet ground) a broken PEN conductor on a PME supply could put the tub's metalwork at a dangerous potential. Where the risk of simultaneous contact is real, a TT arrangement with its own earth electrode and RCD protection removes that hazard. If you go TT, treat it as a proper TT installation: electrode test, RA below 200 Ω and ideally below 100 Ω, and Zs checked against the RCD rather than the MCB. Our SWA and TT versus PME guide (/guides/outbuilding-garden-supply-swa-tt-pme) and the earth electrode testing guide (/guides/earth-electrode-testing-tt-systems) cover the testing.
Whatever you choose, record the earthing arrangement for the outdoor part of the installation on the certificate, and if it differs from the house, say so in the comments.
What RCD type does a hot tub need?
The RCD rating is fixed at 30 mA by Section 702. The RCD type is set by the load. Modern hot tubs use variable-speed circulation pumps and electronic heaters, which can produce DC components or high-frequency leakage that a Type AC RCD cannot see. Regulation 531.3.3 requires the RCD type to suit the residual current expected from the equipment, and manufacturers' installation manuals increasingly state Type A as a minimum, with some specifying Type B for tubs with inverter-driven pumps.
Read the manual before you order the RCBO. If the manual says Type B, a Type A will not comply with 134.1.1 even though it satisfies the 30 mA requirement. Record the RCD type and the measured trip time on the schedule of test results; the RCD testing guide (/guides/rcd-testing-explained) covers the test sequence.
Which certificate and is it notifiable?
A hot tub is almost always a new dedicated circuit, typically 32 A single-phase on 6 mm² or 10 mm² SWA depending on length and volt drop. A new circuit means an Electrical Installation Certificate (/guides/electrical-installation-certificate-eic-explained), not a Minor Works certificate. A swimming pool with plant room, lighting and heating is a full installation and may need several circuits on the one EIC.
In England, the work is notifiable under Part P on two counts: it is a new circuit, and it is work in a special location (Approved Document P lists swimming pools alongside bathrooms and saunas). In Wales the notification rules are similar; in Scotland a building warrant may be needed for pool construction and the electrical work is certified by the installer. The Part P guide (/guides/part-p-notification) covers the scheme route.
On the EIC, the items an assessor will look for are: the earthing arrangement of the outdoor supply; the RCD type and trip times; the Zs at the isolator and at the tub terminals; insulation resistance on the SWA; a note on supplementary bonding (present, or not required and why); and a statement that the manufacturer's installation instructions were followed, which in Certio you can put in the comments on the existing installation or the departures box if you have had to depart from them.
What to look for on an EICR
Hot tubs and pools show up on periodic inspections more often now that the tubs are cheap. Common observations, with the codes we would normally give, are: a 13 A plug-in tub on a socket-outlet without RCD protection (C2); an isolator inside zone 1, reachable from the water (C2); a non-RCD circuit feeding pool lighting in zone 2 (C2); an unbonded metal handrail in zone 1 where other extraneous parts are bonded (C2, or C3 if no other bonding exists and the tub is Class II); an SWA gland with no earth tag and the armour not used as CPC (C2 if it is the only CPC, C3 if a separate CPC is present); and a Type AC RCD where the manufacturer specifies Type A or B (C3 with a note, unless the RCD fails to trip on test, in which case C2). Our observation coding guide (/guides/eicr-observation-codes-c1-c2-c3-fi) sets out the reasoning behind these.
Always record the tub's presence and the zone layout in the extent of the inspection even if you could not access the pump pack, and list the pump pack as a limitation if you did not open it.
Sources
BS 7671:2018+A4:2026 Requirements for Electrical Installations, Section 702 (Regulations 702.11, 702.32, 702.410.3.4, 702.415.2, 702.512.2, 702.53, 702.522, 702.55) and Regulations 134.1.1, 411.3.3, 522.6.204, 531.3.3 and 544.2; IET Guidance Note 7, Special Locations; IET Guidance Note 3, Inspection and Testing; Approved Document P (GOV.UK); Electrical Safety First best practice guidance on outdoor electrical installations; NICEIC technical guidance on hot tub installations.
How Certio helps
Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is free for 7 days, then £5 a month.