Bathroom electrics & Part P
A bathroom is the one room where water and electricity share the same small space, which is exactly why the rules around bathroom wiring are the strictest in the house. Every bit of electrical work in a bathroom falls under Part P of the Building Regulations, has to meet the current wiring regulations, and must be tested and certified on completion. This guide explains what that means in plain terms — the safety zones, the IP ratings, the RCD protection and the certificate you should always be handed — so you know exactly what a properly wired full bathroom installation includes.
What Part P actually means
Part P is the section of the Building Regulations that covers electrical safety in homes. It exists because electricity in the wrong place — near a bath, a basin or a shower — can be lethal, and bathrooms concentrate all three. In practice, Part P means any fixed electrical work in a bathroom must be designed, installed, inspected and tested to the current wiring regulations (BS 7671), and then certified by a competent person. That certificate is your proof that the work is safe and signed off — and you should insist on it.
This isn’t box-ticking. The certification process forces the important safety features to actually be there and to actually work: the right fittings for each zone, proper earthing and bonding, RCD protection, correctly rated cable, and a set of test results that prove the whole installation is sound. A bathroom wired by someone who can’t or won’t certify it is a bathroom you can’t be sure about — and one that can cause you real problems when you come to sell, because a buyer’s solicitor may well ask for the paperwork.
Certified electrics are a standard part of every full installation we carry out — it’s covered in your fixed quote, not sprung on you as an extra. It runs in two stages alongside the plumbing: the electrical first fix chases in the cable while the walls are open, and the second fix fits and connects the fittings before the whole lot is tested and certified.
The bathroom safety zones
The wiring regulations divide a bathroom into zones based on how close things are to water. Each zone allows only fittings rated to survive the amount of water they might meet there, measured as an IP rating (Ingress Protection). Getting the right fitting in the right zone is the heart of safe bathroom electrics.
Zone 0 — inside the bath or shower tray
The wettest place of all — literally where the water sits. Anything here must be low voltage and rated to be fully immersed, typically IPX7. In practice very little goes in Zone 0, and only fittings specifically made for it. This is not somewhere for a standard downlight or socket, ever.
Zone 1 — above the bath or in the shower
The area directly above the bath or within the shower enclosure, up to 2.25m. Fittings here need to be rated at least IPX4 against splashing — more if a shower jet could reach them. Shower lights, ceiling downlights over the bath and an electric shower unit all live in this zone and must be specced accordingly.
Zone 2 — beside the bath or basin
The area stretching 0.6m beyond Zone 1, and around a washbasin. Fittings need to be at least IPX4. Wall lights, the extractor fan and heated mirrors typically sit here, chosen for the right rating. A shaver socket to the correct standard is permitted in Zone 2.
Outside the zones
Beyond Zone 2, normal fittings can be used — but the whole circuit still needs RCD protection and the room still needs proper earthing and bonding. Standard sockets are kept well away from the wet zones, which is why you rarely see a normal plug socket in a bathroom at all.
We work these zones out for your specific room at survey and design the lighting, extractor, shaver point and any electric shower or underfloor heating around them — so every fitting is both safe and suited to where it sits.
What certified bathroom electrics covers
On a full installation, the certified electrical work usually takes in the whole list below. Each item is specced for its zone, wired in correctly rated cable, protected by an RCD, and tested before it’s signed off.
Lighting
IP-rated downlights and any wall or mirror lights, positioned for their zone. Good bathroom lighting is layered — bright for the mirror, softer for ambience — and all of it rated for the damp.
Extractor fan
Wired to run when it’s needed — often humidity-sensing or on an over-run timer — to clear steam and protect the room from damp and mould. Part of meeting the ventilation requirements too.
Electric shower
An electric shower is a high-load appliance needing its own correctly rated cable and circuit protection. Getting the cable size right is essential — undersized cable on a powerful shower is a genuine fire risk.
Underfloor heating
Electric underfloor heating needs its own supply, a thermostat and RCD protection, wired and tested as part of the installation. It’s laid at first fix under the tiles and connected at second fix.
Shaver socket & heated mirror
A shaver socket to the correct standard and any heated, demisting mirror are wired to suit their zone — the small conveniences that make a bathroom feel finished, done safely.
Heated towel rail (electric)
Where a towel rail is electric rather than plumbed, it’s wired and protected properly. On accessible bathrooms we’ll also plan switching and heights around ease of use — see accessible bathrooms.
Earthing, bonding, RCDs & testing
Behind the fittings you can see are the protections you can’t — and they’re what actually keep you safe. This is the part unqualified work most often gets wrong, because it doesn’t show and it’s tempting to skip.
RCD protection
An RCD (residual current device) cuts the power in a fraction of a second if it detects current leaking to earth — for instance, through a person. Every bathroom circuit must be RCD-protected. It’s the single most important safety feature in a wet room full of electrics, and it’s non-negotiable on any bathroom we wire.
Earthing & supplementary bonding
Metal parts — pipes, the bath, the towel rail — need to be properly earthed and, where required, bonded together so they can’t ever be at different voltages. Modern installations may not always need supplementary bonding if certain conditions are met, and part of a competent job is knowing exactly when it’s required and confirming it by test.
All of it is then tested: continuity, insulation resistance, earth loop, RCD trip times and more, with the results recorded on the certificate. That certificate — an Electrical Installation Certificate or Minor Works Certificate depending on the scope — is your proof the work meets the regulations. We hand it over as part of the job, and it’s the document you’ll want if you ever sell the house or a surveyor asks. It sits alongside the ventilation and drainage requirements covered in our bathroom ventilation guide and the wider building regulations guide.
Why bathroom electrics is no place to cut corners
We’re all for saving money where it’s sensible — but the electrics are never the place to do it. A cheap or uncertified job might look identical on the day the tiles go up, because everything dangerous is hidden inside the walls and the consumer unit. The problems surface later, and they’re serious: a downlight fitted with the wrong IP rating over a shower, an electric shower run on undersized cable that overheats, a circuit with no working RCD, or bonding that was quietly left out. Any one of those can turn a bathroom into a genuine hazard.
There’s a paperwork cost too. If you sell the house and can’t show that notifiable electrical work was certified, it can slow a sale, knock the price, or land you with the cost of having the work inspected and put right retrospectively. Building control can also take a dim view of unregistered work. Set against all that, having the job certified from the start is one of the cheapest forms of insurance you’ll ever buy — which is exactly why we build it into every quote rather than treating it as an optional line item.
It’s also worth saying plainly: this is skilled, regulated work, not a weekend DIY job. Swapping a like-for-like light fitting elsewhere in the house is one thing; anything fixed in a bathroom is another. If you’re comparing quotes and one fitter can’t tell you clearly how they’ll certify the electrics, that tells you something important about the rest of their work too.
How the electrics fit the installation
The electrical work threads through the whole job rather than happening in one block, which is why a single accountable team makes such a difference — the sparky and the fitter are working to the same plan, on the same schedule, on the same fixed quote.
At survey
We map the zones for your room and agree the lighting, extractor, shaver point and any electric shower or underfloor heating — so it’s all designed in, priced, and ordered before we start.
At first fix
Cable is chased into the open walls and run back to the consumer unit, clear of pipework and set for the fittings to come. This has to happen before boarding, because you can’t easily re-route cable once the wall’s tiled.
At second fix
The lights, fan, shower, thermostat and accessories are fitted and connected once tiling’s cured, then the whole installation is tested and certified — and the certificate handed to you with the rest of your hand-over paperwork.
Because it’s all costed at survey, there’s no mid-job surprise on the electrical side — the price we quote is the price you pay, wiring and certification included. For how it fits the overall budget, see the cost of a bathroom in Plymouth.
Bathroom electrics & Part P FAQs
Do I legally need certified electrics in a bathroom?
Yes. Fixed electrical work in a bathroom is notifiable under Part P of the Building Regulations and must meet the current wiring regulations, then be tested and certified. This isn’t optional — it’s the law, and the certificate is your proof the work is safe. We carry out and certify all the electrical work as a standard part of every full installation, included in your fixed quote.
Can I have a normal plug socket in my bathroom?
Standard 13A sockets aren’t permitted in the bathroom zones and are kept well away from any wet area — which is why you rarely see one in a bathroom at all. What you can have is a shaver socket to the correct standard, typically in Zone 2. If you want charging points or sockets, they’re best placed just outside the bathroom, and we’ll plan that with you at survey.
Will I get paperwork I can show a buyer?
Yes. On completion you’re handed an electrical certificate recording that the installation meets the regulations, along with the test results. Keep it safe — when you sell, a buyer’s solicitor may ask for evidence that electrical work was done properly, and this is exactly that. It’s part of why certified work protects the value of your home, not just your safety.
Can I keep my existing bathroom lights and fan?
Sometimes, if they’re the right rating for their zone and in good order — but in a full installation the walls are open and it’s usually the right moment to renew them, especially if the layout is changing or the old fittings aren’t correctly IP-rated. We’ll tell you honestly at survey what’s worth keeping and what’s better replaced, rather than charging for changes you don’t need.
Proud of every bathroom we fit
Safe, certified, signed off
Certified electrics aren’t an upgrade — they’re the standard we build to on every bathroom, included in your fixed quote and handed over with the paperwork to prove it. Tell us about your room and we’ll give you one clear written price for the whole job.