If you’re planning a new bathroom or upgrading an existing shower, the choice between electric and mixer models often comes down to your home’s hot water system, available space and budget. An electric shower heats cold mains water instantly, giving you a hot shower without relying on your boiler or hot water cylinder. For many UK homeowners, that independence alone makes it worth serious consideration. This article explains how electric showers work, when they’re a strong fit, what installation looks like in practice, and what you need to know about costs and compliance.
What is an electric shower?
An electric shower is essentially an instant water heater built into the shower unit itself. Cold water from the mains supply passes over a heating element inside the unit, so it reaches your chosen temperature on demand. There’s no need for a hot water tank, boiler connection or separate pump. Most domestic electric showers are rated between 8.5 kW and 10.8 kW, with higher wattages delivering a stronger flow rate.
- 8.5 kW – around 3–4 litres per minute; suitable for single-person use.
- 9.5 kW – about 4–5 litres per minute; a common choice for family bathrooms.
- 10.8 kW+ – 5 litres per minute or more; better flow for multiple users or larger households.
Because they draw cold water directly from the mains, electric showers are largely unaffected by the state of your central heating system. This makes them particularly reliable in homes where the boiler or hot water cylinder is shared across multiple rooms or where space for a large cylinder is limited.
When does an electric shower make sense?
Electric showers are not the right choice for every home, but they offer clear advantages in several common scenarios.
Homes with limited hot water capacity – If your hot water cylinder is small or struggles to keep up with demand (for example, in a busy household or an en-suite added later), an electric shower takes that load off the cylinder. Each shower draws only cold water, so other taps and baths can still use stored hot water.
Properties without a compatible boiler – Gravity-fed systems, older combi boilers, or homes that rely on a back-boiler may not provide enough pressure for a thermostatic mixer shower. An electric shower works from mains cold water pressure alone, so it can deliver consistent performance even when your heating system is less than ideal.
Space-constrained installations – Electric showers are compact. The unit fits on the wall inside the shower area, and there’s no need to run hot water pipes from the cylinder. This makes them a practical option for loft conversions, cloakroom showers, or small bathrooms where pipework routes are difficult.
Retrofit simplicity – A like-for-like electric shower swap is one of the quickest bathroom upgrades. If the existing cable and plumbing are in good condition, a competent electrician can usually complete the job in a single morning. That minimal disruption is valuable in occupied homes.
Hard-to-treat homes – Properties with solid walls, no space for a hot water cylinder, or limited access for pipework can be challenging for mixer or power showers. Electric showers avoid many of those constraints. When combined with a Waste Water Heat Recovery system (WWHRS), some modern electric showers can reduce annual energy use by up to 51% and water consumption by 44% compared with an efficient 8 L/min mixer shower, according to manufacturer performance data.
Understanding installation costs and complexity
Installation costs for an electric shower vary widely depending on the scope of work. It’s useful to think in tiers rather than a single price.
Like-for-like replacement (simple swap) If you’re replacing an existing electric shower with a new unit of similar wattage, and the existing cable and pipework are adequate, the job is straightforward. Expect to pay between £350 and £650 for the complete job, including the unit (typically £150–£400) and the installer’s labour. This is the most cost-effective route.
Upgrading to a higher wattage or new circuit If you want a more powerful shower (e.g., moving from 7.5 kW to 10.5 kW), you may need a new dedicated cable from the consumer unit and a corresponding circuit breaker. That adds complexity and cost. The electrical work alone is often quoted at around £280–£380 per day by a Part P registered electrician, and the total installation might run from £430 to £665 depending on cable routing, wall finish and any plumbing adjustments.
Complete new installation where none existed If there is no existing shower and no dedicated circuit in place, the work includes running a new 6 mm² or 10 mm² cable, installing an RCD-protected breaker, fitting the unit, and making good any tile or plaster damage. This is a multi-trade job and prices typically start around £750 and can exceed £1,400 if the shower enclosure or tray also needs installing.
Factors that most affect the final price:
- Shower wattage (higher kW requires heavier cable and larger breaker)
- Need for a new circuit and RCD protection
- Cable run distance and routing (e.g., through floor voids or walls)
- Tile cutting, plastering or making good
- Existing water pressure – very high mains pressure may require a pressure reducing valve
- Whether the installer needs to provide Building Control certification (see below)
Electrical requirements and safety compliance
An electric shower is one of the highest-load appliances in a typical home, so it must be installed correctly to avoid fire risk and electric shock. The following requirements are specified in BS 7671 (the Wiring Regulations) and Part P of the Building Regulations.
Dedicated radial circuit Every electric shower must be on its own circuit from the consumer unit. It cannot share a circuit with sockets, lighting or other appliances. Cable sizing depends on the shower’s wattage and the length of the run:
- 8.5 kW – minimum 6 mm² cable, 40 A breaker
- 9.5 kW – 10 mm² cable recommended, 45 A MCB or 40 A RCBO
- 10.8 kW – 10 mm² cable, 45–50 A breaker
RCD protection BS 7671 Regulation 701.411.3.3 requires that all low-voltage circuits serving a room containing a bath or shower, and any circuits passing through Zones 1 and 2, have additional protection by a 30 mA RCD. This is typically provided by an RCBO at the consumer unit or an RCD covering the shower circuit. If your existing consumer unit doesn’t have RCD protection, the installation may require a replacement consumer unit or a separate RCD enclosure.
Isolation and bonding A 45 A ceiling-pull isolation switch (or a wall-mounted switch outside the bathroom) must be fitted to allow safe isolation of the shower. Supplementary bonding of the shower unit, pipework and any exposed metal is required unless the main bonding is already adequate under the latest edition of BS 7671.
Part P of the Building Regulations Any electrical work that involves a new circuit, a change to the consumer unit, or work in a bathroom zone is notifiable under Part P. This means the work must be either:
- Carried out by a registered competent person (e.g., NICEIC, NAPIT or ECA registered electrician) who then self-certifies the work, or
- Notified to the local authority Building Control before work starts, which typically comes with a higher fee and possibly an inspection.
A simple like-for-like swap of an electric shower (no new circuit, no consumer unit changes) is often considered non-notifiable, but if you are unsure, it is safest to use a Part P registered electrician who can advise correctly. Always keep the certificate for your records – it will be needed if you sell the house.
Electric vs mixer showers: a quick comparison
Understanding the trade-offs helps you decide which type fits your home best.
| Factor | Electric shower | Mixer shower |
|---|---|---|
| Hot water source | Cold mains only | Hot and cold from boiler or cylinder |
| Boiler dependency | None | Relies on boiler/cylinder and its pressure |
| Water pressure needed | Minimum ~1.0 bar from mains | Varies by system; gravity-fed may give low flow |
| Flow rate typical | 3–5 L/min (higher kW = more flow) | 8–18 L/min if pressure is good |
| Installation cost | Lower (if like-for-like) | Higher if pipework changes needed |
| Running cost per shower | ~8–14p (2026 electricity rates) | Lower if using gas-heated hot water |
| Space needed | Wall unit only | Requires hot and cold pipework; may need pump |
| Energy efficiency | Good with WWHRS; no standing losses | Cylinder heat loss unless insulated |
When an electric shower wins: You have low mains pressure, limited hot water capacity, or you want to avoid boiler dependency. It is also a strong choice for en-suites, loft conversions and homes where running hot water pipes would be expensive or impractical.
When a mixer shower wins: You have excellent mains pressure and a modern combi or unvented cylinder. The flow rate is more luxurious, and if your hot water is gas-heated, the running cost per shower is lower.
Both types can be safe, reliable and efficient when installed correctly. The best choice depends on your specific water pressure, heating system and budget.
Frequently asked questions
Will an electric shower work if my boiler breaks? Yes. Electric showers heat cold water directly from the mains supply, so they operate entirely independently of your boiler or hot water cylinder. You can still enjoy a hot shower even if your central heating is off.
How long does an electric shower installation take? A straightforward like-for-like swap usually takes 2–4 hours. If a new circuit or cable run is needed, allow a full day. Complex installations (new enclosure, tiling work) can take 1–2 days.
What size cable does an electric shower need? For an 8.5 kW shower, 6 mm² cable is typical. For 9.5 kW to 10.8