how to install an electric shower

INSTALLING A SHOWER PAGE 2

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As stated on the previous page a 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 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

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.

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 OUT

FEED LOAD

SUPPLY LOAD

Connecting at the shower unit

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.

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Connecting at the double pole switch
		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,


Double Pole 45 A Pull cord switch with Neon and mechanical ON/OFF indicator		Double Pole 45 A switch with Neon

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

Connecting at the shower unit
	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.