Ultimate Handyman DIY Home wiring an electric shower

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An electrical shower is one of the largest consumers of electricity in the home and no diversity is allowed when calculating the current usage of the appliance. Due to the new electrical rules installing an electric shower is probably best done by a professional electrician, although it is still possible. Please reade here for more information regarding DIY electrics and the law .

All electrical pages are for information only! New rules have been introduced for electrical safety in the home, please read this document by clicking here, before starting any electrical work

Before working on any electrical circuit you must ensure that it is isolated correctly and cannot accidentally be switched back on. Please read the article on safe isolation procedures before doing any electrical work. If you are not 100% certain what you are doing call a qualified electrician. Building regulations are changing all the time and modifying your home electrics could be against new rules and could invalidate your home insurance, if in doubt check first!

 

 

   

 

For instructions on how to build a shower cubicle please click here- Building a shower cubicle

Electric showers are a very economical way of washing, the amount of water used is about a third of that used by having a bath and the shower only heats the correct amount of water so there is no heating of water that you will not use.

If you have a combination boiler you are much better off with a thermostatic mixer rather than a electric shower but if you have a back boiler or similar a electric shower is your only choice!

A electric shower will normally be fitted above a existing bath, you must ensure that the bath is sealed correctly or you will soon have water in the rooms below. Fitting the shower is relatively easy although it is recommended that you get a  qualified electrician to wire it up to the electricity supply, you can wire up the shower yourself but you must first check the new electrical rules. Wiring a shower would require that the local authorities building control department are notified before you start the work.

It is recommended but not mandatory that electric showers are connected to a RCD, if you have a split way consumer unit this is easy but if you have a normal consumer unit or fuse board fitting a RCD will be expensive as you will need an electrician to fit the RCD! It is also recommended that you have an electrician check the circuit and connect the shower at the consumer unit. Luckily I fitted this shower in 2004 before the new part p regulations came into force.

Position of new shower
After finding a suitable location for the shower you need plan a route for the  water pipe, in the example below the shower is being located on the side of an old airing cupboard which has plenty of space and access for the pipe and the cable.

 

 

pipe and cable
Here I have removed the old plasterboard to enable the pipe to be fed to the required point where the shower will eventually be positioned. Note how I have made two holes for the pipe, this is so that an isolating valve could be situated inside of the cupboard, then servicing the shower is easier, sometimes the shower manufacturers insist on this or the guarantee is invalidated.

 

exterior plywood
Then I have inserted some extra noggins to strengthen  the frame and  fixed 1/2 inch exterior plywood to the frame to make fastening the shower unit and riser rail. This will be tiled completely so will not be seen.

 

Isolation Valve

It is essential that an isolation valve is fitted to the water pipe that is supplying the new shower as it is a requirement by most shower manufacturers. A check valve may also be required.

How to fit an isolation valve

 

New shower
After tiling simply fasten the shower unit and the riser rail to the wall with the appropriate fixing

If you are not 100% sure what you are doing then you should not attempt to install the shower yourself and a electrician should be employed to do the installation for you.

As stated above an electric shower is a large consumer of electricity and so requires it's own circuit and own MCB or fuse, there are several rules that you must follow when installing a circuit for a electric shower.Installing a new shower circuit is now covered by Part P and so you can still do the work your self as long as you inform building control first and get it inspected, or you can get a qualified electrician to install and test it for you. If you are simply changing an existing shower with a like for like unit then you do not need to inform Building control.

All metal pipes in the bathroom may need bonding, please see here for more information

The cables need running in the permitted zones, please see here for more information

The cable must be the correct thickness for the shower, this will depend on the rating of the shower in KW and the distance from the consumer unit to the shower. I normally use 10mm2 as this is suitable in most cases, but you will have to find out which cable you need  from a qualified electrician.It is recommended the a shower is fitted to a RCD, but not compulsory! A RCD constantly measures the difference between Live and Neutral and disconnects the supply as soon as a fault occurs. If you have a modern consumer unit you can fit a RCBO which is a combined MCB and RCD in one unit.A shower circuit must have a double pole isolator switch ( disconnects both live and neutral ) that cannot be operated by someone that is using the shower, if your bathroom is small this may mean installing this switch outside of the bathroom. If you have a large bathroom and wish to install the switch in there it must be of a pull cord type that will normally be located on the ceiling.

When routing the cable it should have a route separate from other cables, it should not pass through insulation or thermal plasterboard, if this is unavoidable use 10mm2 cable even on a small run.

Connecting at the double pole switch  
double pole switch connections You can make it easy on yourself by feeding the wire into the backbox of the double pole switch so that the wires are in the correct place.

Here you can see that the two Lives and two neutral wires are in line ready for connecting to the double pole switch.

This switch is located outside of the bathroom, it may be necessary for you to use a ceiling mounted one, with a pull cord.

The double pole switch needs to be of the correct amperage for the load of the shower, there is no harm in using a higher amperage switch but never use a lower amperage switch! The switch should also incorporate a indicator so that it is obvious when the shower is switched on or off, if the switch is a ceiling mounted pull cord switch then it should also have a mechanical on / Off indicator.

pull cord switch
switch with neon
Double Pole 45 A Pull cord switch with Neon and mechanical ON/OFF indicator
Double Pole 45 A switch with Neon
   
This type of switch can be used inside of a bathroom as long as it cannot be reached by someone using the shower!
This type of switch cannot be installed inside a Bathroom or shower room and must be fitted outside of such rooms

 

Double pole switches are marked up on the reverse, so that you know which wires go where. Some of these can be confusing and are labelled up feed and load, some are labelled up supply and load and others that are more sensibly designed say In and Out!

From consumer unit   To the appliance
IN
to
OUT
FEED
to
LOAD
SUPPLY
to
LOAD

Connecting at the shower unit

 

 

   

electrical connections

 

1. Cable entry point

2. Cable clamp

3. Earthing terminal

4. Connector Block The wire enters the shower through the cable entry point (1)

The wire is then stripped sufficiently for the Neutral and Live wires to be joined to the connector block (4)The most important connection is the earth, this wire is normally bare and needs sleeving with green and yellow sleeving. The earth wire is fastened securely to the earthing terminal (3), this is normally done with a nut.

The cord grip should be tightened(2) so that it grips the wire and prevents it from being removed from the shower.

 

The connections that you make at the consumer unit depend on which type of consumer unit that you have. It is not mandatory that a shower is connected to a RCD but I strongly recommend it. An RCD is a great safety device and is money well spent.

If you have a fused consumer unit like the one below it is advisable to use a dedicated Shower RCD and MCB like the one on the right hand side. In most cases this can be wired into a fuse of the correct Amperage using the correct thickness of cable.

fused consumer unit shower rcd
Fused consumer unit Shower RCD and MCB

 

 

         
If you have a fully RCD protected consumer unit you can wire the shower directly into the correct amperage circuit breaker. If you have a split way consumer unit you must ensure that the shower is wired into the RCD protected side of the unit.

 

 

rcd consumer unit  Modern split way consumer unit
RCD consumer unit
Split way consumer unit

         

 

 

 

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