How to fit an electrical shower - Easy installation guide

Jonathan	Nolan By Jonathan Nolan, 14th Jun 2018 | Follow this author | RSS Feed
Posted in Wikinut>Guides>DIY>Electrical

A guide on fitting and electrical shower in your home yourself. Saving on builder costs!

An introduction to how electricity works

Never work on any part of the electrical installation without first switching off the supply at the consumer unit and, where possible, removing the circuit fuse. Always unplug any electrical appliance before doing any work on it. Check all connections are secure and all covers have been replaced before you turn the electricity on again.

Seeking professional help or advice

If you don't feel competent to do a particular job, always seek the advice of a professional electrician. Make sure that any person you hire is fully qualified. A person registered with the Electrical Contractors Association/ NICEIC, will be approved for undertakingthis type of work and will be well versed in all the wiring regulations for electrical installations in buildings.

Simplified view of the overall electrical distribution

Electricity is fed to the consumer over a complex network of cables. Very high voltages are needed to supply the energy over long distances and are carried by lines suspended from transmission towers. Transformers set up these high voltages, subsequently, reducing them to more manageable distribution levels. Eventually, reducing to, a voltage that can be safely connected to the house.

Throughout the supply network the electricity is distributed in three phases. Effectively, the system combines three separate generators within the one system. A saving in materials is achieved, only three, (or four), supply lines are required, instead of the six required by three separate single-phase systems. At the house, one single-phase supply is provided, the connection details are shown.

The supply input arrangements for the house

The consumer's mains equipment is fixed close to the point where the supply cables enter the home. The actual supply arrangement will normally be either:

The TT System, (mainly used in rural areas)
The TN-CS System, (commonly used for urban districts)
The TN-S System, (used in some urban districts)

Short circuit faults

Short circuits occur when the live and neutral become directly connected. They are usually caused by accidents or carelessness in checking that a newly installed circuit is safe before switching on. In the home, the short circuit fault current is not likely to exceed 10kA and is usually less than 2kA, (2000A). However, the damage cause by the short circuit can be extensive and they must be isolated immediately.

Earthing faults

Earth faults occur when the live conductor makes accidental contact with the surrounding earth protected metal casing. The fault current is returned via the protective conductor or finds its own path. Earth fault currents are not usually as large as the short circuit values, but they still can cause extensive damage and need to be quickly isolated. For portable equipment the isolation time needs to be less than 0.4s.

Fitting your new shower


This sheet gives gives a brief outline, on how to fit an electrical shower unit. It is recommended that you follow individual manufacturers' instructions as well as the following steps:

1 - Choosing the power output of your shower.

2 - Safety features of the showers.

3 - About water pressure.

4 - Arranging the water supply.

5 - Arranging the electrical supply

6 - Arrange the waste discharge from the shower.

7 - Specific installation instructions.


Plumbing tools, electrical tools, drill


Appropriate pipe run, appropriate electrical supply, double pole switch

Choosing the power output of your shower

The power rating of the shower determines the maximum water flow rate. For a hot shower, a 7kW heater has a maximum flow rate of approximately 2litres/3.5 pints per minute. This rate is adequate and not wasteful, but may not be sufficient to overcome a very cold water supply in winter. A 9.5kW unit will give a hot shower at a much more forceful flow rate.

Safety features of the shower

Changes in pressure of the water are dealt with internally by the shower unit so the temperature of the water remains constant.

About water pressure

An electrical shower unit can be fed from the mains system as long as there is adequate pressure, usually 1 bar. If the water pressure falls below the adequate level the unit will shut down automatically or will not function properly. Where the pressure is low, a booster pump will be required. If in doubt consult your water authority.

Arranging the water supply

Supply for your shower should come from the rising main. Use a run of 15mm copper pipe to make the connection and include an isolating valve and double check valve within it. Run the pipe work from the shower before making the connection to the rising main.

Arranging the electrical supply

Showers must be on there own radial circuit directly from the consumer unit. The size of protective device required will depend on the specific kW of the heating unit.

Arranging the waste discharge from the shower

If the shower is in a new area then you must plan the discharge accordingly. There are several waste systems available.

Specific installation instructions

Comprehensive installation instructions are supplied with the shower heater. First choose a location over a bath or shower cubicle. Fit on a finished surface, if this is tiled click on the icon below to find out more. Plan the pipe work and waste carefully. Do the plumbing before the wiring so you can rectify any leaks before you introduce electricity.

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