Install an electric shower.

Whether you are replacing an old unit or installing a powerful new 10.8kW model, ensuring your consumer unit and cabling can handle the load is critical. This guide covers everything you need to know about the costs, regulations, and technical requirements for a professional installation.

What Does the Work Involve?

• Site Assessment: Checking the existing consumer unit (fuse box) to ensure it has the capacity and RCD protection for the shower's power rating.
• Isolation: Safely turning off the water and electricity supplies before removing any existing hardware.
• Cable Routing: For new installs, pulling the correct gauge of twin and earth cable (usually 6mm or 10mm) from the consumer unit to the bathroom.
• Plumbing Connection: Connecting the unit to the cold water mains using a compression fitting and an isolation valve.
• Electrical Wiring: Terminating the live, neutral, and earth wires into the unit and installing a ceiling-mounted pull-cord isolation switch.
• Testing and Commissioning: Verifying the earth continuity, checking for leaks, and ensuring the thermal cut-out functions correctly.

Typical Costs

The total price is heavily influenced by the distance between your bathroom and the consumer unit. If an electrician has to lift floorboards or chase cables into walls to run a new 10mm cable, labour costs will increase significantly.

Pro Tip: Upgrading from a 7kW to a 10.5kW shower usually requires thicker cabling. Never swap a unit for a higher-powered model without having an electrician verify your existing cable gauge first.

How Long Does It Take?

• Like-for-like replacement: 1–2 hours. This is a straightforward swap where the plumbing and electrics already line up.
• New installation (standard): 4–8 hours. This involves running a new dedicated circuit from the fuse box to the bathroom.
• Complex installation: 1–2 days. Required if extensive routing through walls or floorboards is needed, or if the consumer unit needs replacing.

DIY or Professional?

In the UK, electric shower installation is not a DIY job. Bathrooms are classified as "special locations" under Building Regulations, meaning most electrical work here is "notifiable."

A professional electrician ensures the unit is earthed correctly and protected by an RCD (Residual Current Device), which disconnects the power instantly if a fault occurs. Attempting this yourself is not only dangerous but can invalidate your home insurance and make it difficult to sell your property without a Part P certificate.

Choosing the Right Tradesperson

• Check Credentials: Ensure they are registered with a competent person scheme such as NICEIC, NAPIT, or ELECSA.
• Plumbing Skills: Many electricians are happy to handle the minor plumbing involved, but verify this upfront or you may need a plumber too.
• Get a Written Quote: Ensure the quote specifies whether they are supplying the shower unit or if you are providing it.

Questions to ask:

• "Are you Part P registered and will you provide a Minor Electrical Works Certificate?"
• "Is my current consumer unit up to date, or will it need an RCD fitted?"
• "Does the existing cable gauge support the kW rating of the shower I've chosen?"

UK Regulations

• Part P (Building Regulations): Covers electrical safety in dwellings. Most bathroom electrical work must be notified to Local Authority Building Control.
• BS 7671 (Wiring Regulations): The national standard for electrical installations. Your electrician must ensure the install meets the latest "18th Edition" standards.
• Zoning: Electric showers must have a specific IP (Ingress Protection) rating depending on where they are situated in relation to the bath or cubicle.
• Isolation: A double-pole isolation switch (usually a ceiling pull-cord) must be installed outside the reach of someone using the shower.

Common Problems

• Undersized Cabling: Using 6mm cable for a 10.5kW shower can cause the cable to overheat and potentially start a fire.
• Limescale Buildup: In hard water areas, internal heating elements can fur up, leading to reduced pressure or "surging" temperatures.
• Burned Out Switches: Loose connections in the pull-cord switch often lead to overheating and a smell of burning plastic.
• Pressure Issues: Electric showers require a minimum "maintained" pressure to function; if your mains pressure is too low, the unit may frequently cut out.

Frequently Asked Questions