What Affects the Cost of Fitting an Electric Shower?

Electric showers heat water instantly as it passes through, which makes them one of the most power-hungry appliances in a home. A typical unit is rated somewhere between about 7.5kW and 10.5kW, drawing a heavy current whenever it runs. That's why the electrical work matters so much, and why two quotes for "fitting a shower" can describe very different jobs. This guide explains the factors; it doesn't give prices, because every installation is different.

Like-for-like replacement or an upgrade?

The simplest job is swapping an old shower for a new one of the same rating, on a circuit that was correctly installed and is still in good condition. The electrician disconnects the old unit, connects the new one, and tests the circuit. Even here, testing may reveal problems, such as a damaged cable or poor connections at the isolator, that need fixing first.

Moving to a higher kW shower is different. A more powerful unit draws more current, and the existing cable and protective device may not be rated for it. Fitting a higher-rated shower on an undersized cable risks overheating, so the circuit has to be checked before anything is connected.

A new circuit and cable size

If there's no existing shower circuit, or the old one isn't suitable, a new one has to be run from the consumer unit to the bathroom. Cable size depends on the shower's rating, the length of the run and how the cable is installed: cable buried in insulation in a loft, for example, needs to be larger than cable clipped to a joist. Longer runs, solid floors, finished decoration and difficult access all add time.

Consumer unit capacity

The new circuit needs a spare way in the consumer unit with suitable RCD protection. If the board is full, very old, uses rewireable fuses or has no RCD protection, it may need upgrading or extending before a shower can be added. The overall demand on the supply also matters: a shower, an EV charger and an electric oven running at once can be a lot for some installations. Our guide to consumer unit upgrade costs explains what affects that part of the work.

The isolator switch

Every electric shower needs a double-pole isolator rated for its current, usually a ceiling pull-cord switch in the bathroom or a wall switch outside it. Older or under-rated switches can overheat with a modern shower, so replacing the isolator is often part of the job. Its position also affects the cable route.

Plumbing and bathroom work by others

An electrician handles the electrical side. The water supply, any changes to pipework and the tiling are normally done by a plumber or bathroom fitter. When a shower is moving to a new position, or a bathroom is being refitted, coordinating the trades so the cable is in place before walls are tiled saves time and avoids disturbing new finishes.

Testing and certification

Bathrooms are a special location in the wiring regulations, and a new shower circuit is notifiable work in England. The work is tested on completion and you receive the appropriate certificate. Allow for this when comparing quotes: a quote that leaves out testing and certification isn't comparing like with like.

Getting an accurate quote

To quote accurately, an electrician needs to know the rating of the old and new showers, where the consumer unit is, the route to the bathroom and whether there's an existing circuit. Photos of the consumer unit, the shower and the isolator are a good start. See our electric shower installation page for how we approach the work. For a fixed quote, call 01235 430442.