How to Price an Electric Shower Installation
An electric shower needs its own high-current circuit, so the price is driven by the cable run to the board and whether there is spare capacity — not by fitting the shower itself.
Fitting an electric shower is mostly an electrical job: a modern 9–10.5 kW unit draws a heavy current and needs a dedicated, correctly-sized circuit with RCD protection and local isolation. The price is dominated by the cable run from the board to the bathroom and whether the board can take another high-load circuit.
This guide covers sizing the circuit for the shower's kW rating, surveying the route, the special-location rules that apply in a bathroom, and how to certify and quote. It assumes a new dedicated circuit installed to BS 7671, Amendment 2.
Key takeaways
- An electric shower needs its own dedicated circuit sized to its kW rating.
- The cable run to the consumer unit is the main cost — survey it before quoting.
- RCD protection is required, and a bathroom is a special location with specific rules.
- Check the board has spare capacity and the supply can take the load.
- The install is notifiable and needs an Electrical Installation Certificate.
Size the circuit to the shower
The shower's kW rating sets the design current, which sets the cable size and protective device. A 10.5 kW shower on a 230 V supply draws around 45 A, so you are typically looking at a 10 mm² cable and a 45–50 A device, adjusted for the installation method, length and grouping. Never assume a cable size — calculate it for the specific run.
A too-small cable on a long run is a fire and voltage-drop problem, and an undersized existing circuit inherited from a smaller shower must be upgraded, not reused.
Calculate, don't guess
Work the cable size from the shower's rated current, the run length and the installation method. A cable-sizing check takes minutes and keeps you the right side of BS 7671.
Survey the route and the supply
The cable run from the consumer unit to the shower is where the labour lives. A first-floor bathroom above the board with a clear route is quick; a bathroom at the far end of the house with solid walls, chasing and making good is a very different quote. Note the pull-cord or double-pole isolator position and the shower unit location.
Check the consumer unit has a spare way and enough capacity, and that the supply and main fuse can take another heavy load — a new shower circuit on a maxed-out board may force a board upgrade, which is a separate quote.
Doing this on a job? Electrical Installation Certificate — part of TradePlanr. Free to start, no card needed.
Special-location rules and RCD protection
A bathroom is a special location under BS 7671 Section 701, with zones that dictate what equipment can go where and IP ratings for accessories. The shower circuit requires RCD protection, and supplementary bonding may be required unless the conditions for omitting it are met. Local isolation must be by a pull-cord or an out-of-zone double-pole switch.
Getting these details right is part of the job and part of the price — they are not optional extras.
Certify it on site
Issue the Electrical Installation Certificate for the new shower circuit from TradePlanr with the test results, so the customer has proof of a compliant, notified install before you leave.
Building and presenting the quote
Price the cable and accessories, the labour for the run and making good, and the test-and-certify time. Be clear about what is included: the circuit, the isolator, testing, the certificate, and building control notification. State whether removing the old shower and any redecoration are in or out.
If a board upgrade is likely to be needed, flag it as a priced option rather than discovering it on the day.
From guidance to action
Frequently asked questions
Does an electric shower need its own circuit?
Yes. A modern electric shower draws a heavy current and requires a dedicated circuit sized to its kW rating, with RCD protection and local double-pole isolation. It cannot share a circuit with other loads.
What size cable does an electric shower need?
It depends on the kW rating, run length and installation method. A 10.5 kW shower typically needs 10 mm² cable and a 45–50 A device, but you must calculate it for the specific circuit rather than assume.
Is fitting an electric shower notifiable?
A new circuit for an electric shower in a bathroom is notifiable work. It requires an Electrical Installation Certificate with test results and notification to building control, usually via your competent person scheme.
Related guides
Electric Shower Installation
Cable sizing, protection, isolation and bathroom-zone rules for an electric shower circuit.
Electric Shower Keeps Tripping: Causes and Fixes
A tripping shower almost always means a failing element leaking to earth — how to confirm and trace it.
Cable Sizing to BS 7671
The full cable sizing method — design current, correction factors, tabulated ratings and volt drop.
