Every price is an example you replace with your own quote; this electric shower installation cost calculator holds no market data. The current figure is a design estimate only: cable size, protective device and RCD protection must be designed, installed, tested and certified by a qualified electrician to BS 7671, with Part P applying in England and Wales.
Formula and breakdown
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This electric shower installation cost calculator prices fitting an electric shower in a UK home, whether it needs a brand-new circuit, an upgrade to a higher kW model or a straight swap. It adds the unit, labour, cable, protective device, plumbing and VAT, and it also shows the current your chosen rating draws, so you can see before the survey whether the existing circuit is likely to be enough.
Quick answer: An electric shower installation cost calculator adds the shower unit, labour, any new cable and protective device, plumbing, board work and VAT. A 9.5 kW shower rated at 230 V draws about 41 A, so it needs its own circuit; a new circuit is notifiable under Part P and must be installed by a qualified electrician.
What Is an Electric Shower Installation Cost Calculator?
An electric shower installation cost calculator is a tool that estimates the full price of fitting an electric shower by adding each part of the job and showing the electrical load it creates. In plain words: total equals the unit price plus labour hours times the hourly rate, plus cable length times the price per metre and the new protective device when a circuit is added or upgraded, plus any consumer unit work, plus plumbing and making good, plus VAT, plus a building control fee when the work is not self-certified.
The electrical side matters because an electric shower heats water as it flows, using a large element. The current it draws equals the power in watts divided by the voltage, and that current decides whether the existing cable and breaker can cope. Every price in the tool is an example to replace with your own quotes, because no official source publishes installation prices.
How Do You Use the Electric Shower Installation Cost Calculator?
- Choose the job: a new shower on a new circuit, an upgrade to a higher kW model, or a like-for-like swap.
- Enter the shower’s kW rating and the voltage that rating is quoted at, from the data plate or manual.
- For a swap or upgrade, enter the rating of the breaker or fuse that protects the existing shower circuit.
- Replace the example unit price, labour, cable and device figures with the lines on your quote.
- Add any consumer unit work and plumbing, choose the certification route and VAT, and enter your quoted total.
- Read the total, the current draw, the circuit check and the Part P note, then open the breakdown to see every sum.
How Many Amps Does an Electric Shower Draw?
Current in amps equals the rating in watts divided by the voltage, so a 9.5 kW shower at 230 V draws 9,500 / 230 = 41.3 A. That is far more than any socket circuit appliance, which is why the shower is supplied by its own circuit from the consumer unit. The table shows the current for ratings sold today, such as the 8.5, 9.8 and 10.8 kW models in the Mira range, worked out at 230 V.
| Shower rating | Current at 230 V | Current if the rating is quoted at 240 V | Power delivered at 230 V if rated at 240 V |
|---|---|---|---|
| 7.5 kW | 32.6 A | 31.3 A | 6.89 kW |
| 8.5 kW | 37.0 A | 35.4 A | 7.81 kW |
| 9.5 kW | 41.3 A | 39.6 A | 8.72 kW |
| 9.8 kW | 42.6 A | 40.8 A | 9.00 kW |
| 10.5 kW | 45.7 A | 43.8 A | 9.64 kW |
| 10.8 kW | 47.0 A | 45.0 A | 9.92 kW |
The last column uses the resistive heating relation described in the Wikipedia article on Joule heating: for a fixed element, power changes with the square of the voltage. Check which voltage your shower’s rating is quoted at before comparing models. You can convert any appliance rating with the kW to amps converter or test the relation with the Ohm’s law calculator.
Can You Fit a Higher kW Shower on the Existing Circuit?
Only if the existing cable and protective device are rated for the new, higher current, which the electrician must check. Mira, a shower manufacturer, notes that with a higher rating you may need to change existing cables to withstand higher currents, and that you will always need a professional electrician to install an electric shower.
The electric shower installation cost calculator compares the current your new model draws with the breaker or fuse rating you enter. If the current is higher, the result flags that the cable and protection must be checked and are likely to need upgrading, so budget for the cable run and device. Long runs also add voltage drop, which the electrician considers when choosing the cable; the voltage drop calculator shows how length affects it. Choosing cable size and protection is design work under BS 7671, not something to pick from a table at home.
Is Fitting an Electric Shower Notifiable Under Part P?
A new circuit is notifiable in England and Wales, and so is any addition or alteration to existing circuits in a room containing a bath or shower. Both come from regulation 12(6A) of the Building Regulations as set out in paragraph 2.5 of Approved Document P on GOV.UK, and paragraph 2.6 adds that even minor additions and alterations in the bath or shower zone are notifiable.
Paragraph 3.1 gives three routes: a registered competent person who self-certifies, a registered third-party certifier appointed before work starts, or notifying a building control body before work starts. The tool adds a building control fee only when you choose the second option in the certification menu. Ask your electrician whether a straight swap counts as an alteration in your case, and expect an Electrical Installation Certificate for notifiable work.
What Changes the Total in the Electric Shower Installation Cost Calculator?
The biggest jump is between a swap and a new circuit, because a new circuit adds cable, a protective device, an isolator, more labour and sometimes consumer unit work. Other drivers are the cable route length, how much making good is needed after cable runs through walls and ceilings, the plumbing to bring a cold feed to the new position, and the model you choose. If there is no suitable spare way, price a new board with the consumer unit replacement estimate and enter it on the board work line.
Worked Example: Upgrading From 8.5 kW to 10.8 kW
Example: a household replaces an 8.5 kW shower with a 10.8 kW model rated at 230 V. The existing shower circuit is protected by a 40 A breaker. The quote lists a £250 unit, 4 hours of labour at £50 an hour, a 12 m cable run at £4 per metre and a £30 device, with no plumbing changes. The electrician is registered and charges VAT.
- Current: 10,800 / 230 = 47.0 A, which is above the existing 40 A device, so the circuit needs upgrading.
- New circuit parts: 12 x £4 + £30 = £78.
- Labour: 4 x £50 = £200.
- VAT: (£250 + £200 + £78) x 20% = £105.60.
- Total: £250 + £200 + £78 + £105.60 = £633.60.
A quote of £600 is about £34, or 5.3%, below this build-up. If the same household chose a 9.5 kW model instead, the electric shower installation cost calculator shows 41.3 A, still above 40 A, so the cable upgrade would still be needed. Running costs for each rating can be compared with the electric shower running cost estimate.
Frequently Asked Questions
How much does it cost to install an electric shower?
It is the shower unit plus labour, plus cable, a protective device and an isolator if the shower needs a new circuit, plus plumbing, VAT and any consumer unit work. No official body publishes a national price, so enter your quotes and compare the lines each one includes.
Does an electric shower need its own circuit?
An electric shower draws a large current, about 41 A for a 9.5 kW unit rated at 230 V, so it is supplied by its own circuit from the consumer unit. The electrician designs the cable and protective device for that current to BS 7671.
Can I fit a higher kW shower on my existing cable?
Not without checks. A higher rating draws more current, and Mira advises that you may need to change existing cables to withstand higher currents. Enter the new rating and your existing breaker size in the calculator; if the current is higher, budget for a new cable and device.
Is installing an electric shower notifiable under Part P?
A new circuit is notifiable in England and Wales, and so is any addition or alteration to circuits in a room containing a bath or shower. A registered competent person can self-certify the work; otherwise a building control body must be notified before work starts.
Why does my shower give less power than its kW rating?
The rating applies at a stated voltage. A heating element’s power rises and falls with the square of the voltage, so a shower rated at 240 V delivers about 8 percent less at 230 V. The calculator shows the power at 230 V from the rating voltage you enter.
Do I need a new consumer unit for an electric shower?
Only if the board has no suitable spare way or cannot accept the protective device the electrician specifies. Ask during the survey. If a new board is needed, price it separately with our consumer unit replacement estimate and add it to the board work line.
Checked October 2026 by the Solaxyra Editorial Team. Sources: Approved Document P, 2013 edition (PDF), GOV.UK: Approved Document P, Mira Showers: kW ratings explained, Mira Showers: How to replace and fit an electric shower, Wikipedia: Joule heating, GOV.UK: VAT rates.