Summary
Hot tub installation is overwhelmingly sold and delivered by hot tub retailers as a supply-and-place service, but the electrical connection is very often subcontracted to (or arranged separately with) a qualified electrician — and it's here that pricing goes wrong most often, because retailers frequently understate what "just wire it in" actually involves. A hot tub is not a simple 13A plug-in appliance in the way retail marketing sometimes implies (some smaller "plug-and-play" spas genuinely are, but most 4kW+ hardwired hot tubs are not) — most hardwired domestic hot tubs need a dedicated circuit, correctly sized cable, and specific RCD and isolation arrangements because they sit within a BS 7671 Section 702 special location (swimming pools and other basins).
The pricing driver isn't the hot tub itself — it's what already exists at the property. A consumer unit with a spare way and RCBO/RCD protection close to the tub location is a modest job. A consumer unit that's full, doesn't have appropriate RCD protection, or is a long cable run away (needing trenching across a garden, potentially under a path or driveway) turns this into a significantly bigger job, and quoting without first confirming the existing consumer unit's capacity and the cable route is the most common way this work gets under-priced.
Key Facts
- Notifiable work — new circuit installation for a hot tub is notifiable under Building Regulations Part P; must be self-certified by a registered competent person (NICEIC, NAPIT etc.) or notified to and inspected by Building Control.
- BS 7671 Section 702 — the special locations section covering swimming pools and other basins (which includes hot tubs/spas); defines zones around the tub (Zone 0, 1, 2) with different permitted equipment and protection requirements in each.
- Dedicated circuit — most hardwired hot tubs (typically 3kW–7kW heater load plus pumps) need their own circuit from the consumer unit, not a shared circuit or standard socket — sized to the manufacturer's stated load.
- RCD protection — a 30mA RCD (or RCBO) is required for the circuit, consistent with special-locations requirements for equipment in and around water.
- Isolation — a local isolator switch is typically required within reach of the tub but positioned to comply with the zone restrictions (i.e., not within the zone where standard switchgear is prohibited) — usually at least 3m from the water's edge, or per manufacturer/zone guidance.
- Cable type — outdoor/underground cable runs typically use SWA (steel wire armoured) cable, correctly buried at regulation depth or in ducting, with appropriate glanding and termination at both ends.
- Equipotential bonding — supplementary bonding of accessible metalwork within the zones may be required depending on the installation, per Section 702's bonding requirements.
- "Plug-and-play" spas — genuinely smaller/lower-power inflatable or entry-level spas that are designed to run from a standard 13A socket on an RCD-protected circuit are a real, distinct product category from hardwired hot tubs — always confirm which type is being installed before quoting, since the electrical scope differs enormously.
- Consumer unit capacity — the most common reason a "simple" hot tub electrical job turns into a bigger one: an older or fully-populated consumer unit may need a spare way, an upgrade, or even a full consumer unit replacement to accommodate the new circuit safely.
- Trenching — where the tub sits away from the house, SWA cable typically needs to be laid in a trench at appropriate depth (or in ducting under hard landscaping/driveways), which can be a significant labour cost on its own, especially crossing patios or driveways that need reinstating.
- Manufacturer spec sheet — always work from the specific hot tub model's electrical requirements (load, phase, breaker size) rather than assuming a generic figure — this varies meaningfully between models.
Quick Reference Table
Spending too long on quotes? squote turns a 2-minute voice recording into a professional quote.
Try squote free →| Job element | Typical price | Notes |
|---|---|---|
| Dedicated circuit, consumer unit has spare capacity, short run (<10m) | £350–£650 | RCBO way, cable, isolator, testing/certification |
| Longer cable run (10–25m), some trenching | £650–£1,200 | Labour-dominated: trench digging/reinstatement |
| Consumer unit upgrade required (no spare capacity) | +£400–£1,200 | Depends on full replacement vs added board |
| Trenching under driveway/patio (core drill or breaking out) | +£200–£800 | Reinstatement cost included |
| Plug-and-play spa (13A socket circuit only) | £120–£300 | RCD-protected outdoor socket installation |
| Full installation incl. certification and Part P notification | Add to above | Certificate issue, Building Control notification if not self-certified |
Detailed Guidance
Confirming the job type before quoting
HOT TUB ELECTRICAL JOB TRIAGE
-------------------------------
Check manufacturer spec sheet FIRST:
"Plug-and-play" (13A, RCD socket)?
-> Small job: outdoor RCD-protected socket circuit
Hardwired (dedicated circuit, 16A-32A+ typical)?
-> Full Section 702 special-locations job:
- dedicated circuit + RCD/RCBO
- correct cable size/type for run length
- isolator positioned per zone rules
- equipotential bonding if required
- Part P notification/certification
Why the consumer unit is the real pricing variable
The hot tub's own electrical requirement is usually well-documented by the manufacturer and predictable. What varies job to job is what's already at the property: a modern consumer unit with dual RCD split and a spare way is a straightforward add; an older unit at capacity, or one without adequate RCD protection across the board, means the electrician is now pricing a partial or full consumer unit upgrade as well — a materially bigger job that should be surveyed and quoted separately from the "just connect the tub" assumption many customers arrive with.
Cable routing and trenching reality
Hot tubs are frequently sited away from the house for practical or aesthetic reasons, which means the SWA cable run often crosses open garden, and sometimes needs to go under a path, patio or driveway. Trenching by hand across soft ground is a modest labour addition; needing to break out and reinstate hard landscaping, or core-drill through a wall/foundation, adds real cost that's easy to miss on a phone-quote before seeing the site.
Frequently Asked Questions
Can I just plug a hot tub into a normal socket?
Only if it's genuinely a "plug-and-play" spa designed by the manufacturer to run from a standard 13A socket — and even then, that socket needs to be suitably RCD-protected and rated for outdoor/damp-location use. Most hardwired domestic hot tubs are not designed to run from a standard socket and need a dedicated circuit sized to the manufacturer's load — check the specific model's spec sheet, don't assume.
Is hot tub wiring notifiable Building Regulations work?
Yes. New circuit installation is notifiable under Part P. It must either be self-certified by a registered competent person (NICEIC, NAPIT, etc.) or notified to Building Control for inspection and certification. This applies regardless of whether the work is subcontracted from a hot tub retailer or arranged directly with an electrician.
What is BS 7671 Section 702 and why does it matter for hot tubs?
It's the special locations section of the UK Wiring Regulations covering swimming pools and other basins, which includes hot tubs and spas. It defines protection zones around the water (with different rules on permitted equipment, RCD protection, and bonding in each) — this is why a hot tub circuit isn't just "any outdoor circuit" but has specific positioning and protection requirements for the isolator switch, socket outlets and any other electrical equipment nearby.
Why did my hot tub quote come back much higher than expected?
The most common reason is the existing consumer unit not having spare capacity or adequate RCD protection, requiring an upgrade alongside the new circuit — or a longer cable run than expected requiring significant trenching, particularly where hard landscaping (patio, driveway) needs to be crossed and reinstated. Both of these are site-specific and can't be accurately quoted without a survey.
Regulations & Standards
Building Regulations Part P (Electrical safety – dwellings) — notification requirements for new hot tub circuits.
BS 7671 (IET Wiring Regulations), Section 702 — special locations: swimming pools and other basins, covering zones, RCD protection and bonding for hot tub/spa installations.
Electricity at Work Regulations 1989 — general electrical safety duties applicable to the installer.
IET — BS 7671 Wiring Regulations — the governing wiring standard, including Section 702.
GOV.UK — Building Regulations Part P: Electrical safety — notification requirements.
NICEIC — Special locations guidance — competent person scheme technical guidance on Section 702 installations.
Electrical Safety First — outdoor electrics guidance — safety guidance for garden and outdoor electrical installations.
hot tub installation pricing guide — the broader hot tub supply-and-install cost picture
consumer units — consumer unit capacity and RCD/RCBO context
sauna installation pricing guide — comparable garden-leisure electrical connection job
ev charger installation types — comparable dedicated-circuit garden/outdoor electrical job for cost/method comparison