Fitting an Electric Shower: Planning the Installation
PLANNING THE INSTALLATION
The easiest place to position a shower is on the end wall over the bath, where drainage is already taken care of and there is probably some form of splash-resistant surface. The drawback is that this doesn’t provide a separate shower facility — often the main reason for having a shower in the first place.
If you do choose the bath, make sure the surfaces around the shower are suitable — either tiles with waterproof grout, or eggshell paint. You may need to extend a tiled splash-back to suit, in which case do so after fitting the shower so that the pipe and cable can be buried in the wall. You should also decide what other splash protections you need — either a curtain or splash panels — and position the shower unit accordingly.
A separate shower cubicle can go in the bathroom, a bedroom, a downstairs cloakroom— or even under the stairs. The main restriction is whether or not you can run a 38mm (1-1/2") waste pipe from here to a nearby stack or gully. Also, showers mustn’t be fitted within 2.5m (8′ 2-1/2") of a power socket or conventional light switch.
Check the points shown below before finalizing what you need, then make a list. In particular, decide how you are going to hide the pipe and cable — see Problem Solver – Surface Mounting Pipes and Cables if the shower area is tiled, and you need to surface mount them.
The shower unit canand plug to a masonry wall. On a stud wall, you must directly to the frame timbers – if necessary, by cutting out the plasterboard and fixing extra between studs.
The coldshould be an independent branch taken direct from the rising main to avoid pressure problems when the shower is in use. In most houses where the shower is going upstairs, it’s generally simplest to tee off the pipe supplying the cold water storage tank.
In a direct system with no tank, tee off the main pipe supplying the upstairs plumbing fittings — not off a branch to a basin or bath.
Pipework can be copper, plastic or stainless steel. Plastic is convenient, but the joints may be too bulky if burying the pipe or surface mounting. Stainless steel is a good choice for pipes left on show.
If you decide to bury the metal pipe in the wall, either use the plastic coated type, or wrap the pipe in a protective tape such as ‘Denso’; plaster can corrode bare metal.
Work out the pipe route to take advantage of any cavities, boxing-in or inconspicuous corners. In many cases, the supply cable can follow part or all of the same route (see also Problem Solver – Surface Mounting Pipes and Cables).
A common arrangement when teeing off near the cold storage tank is to run the pipe through the floor, down the corner, and across the wall to the shower.
Connections at the shower may be via a threaded 1/2" BSP fitting, a compression elbow or a combined stopcock/connector; check the fitting instructions when you buy.
Thesupply must be via a separate cable wired to its own fuseway in the consumer unit; the size of cable and the fuse rating of the circuit are determined by the total length of the run and by the power output of the shower.
A suitable double pole isolating switch must be fitted in the supply cable. Normally, it’s best to use a 45 amp pull cord ceiling shower switch.
Check the seals
"When fitting a shower over the bath, don’t forget to check the condition of the sealant between the bath and the wall —many people overlook this, only to find that the ceiling comes crashing down a few months later because the water has seeped down behind the bath and gathered in the ceiling cavity."