Fitting the Electrical Unit

Electric showers have definite advantages and disadvantages. They are relatively cheap to buy, and fairly simple to install. Requiring only a cold supply direct from the rising main, there is no need for cold water storage. The water is heated instantly, as it is forced through the shower unit’s heating element under mains water pressure. A built-in, thermostatically controlled safety valve controls the temperature, and will switch itself off automatically if the water pressure is too low. Ensure that a non-return valve and an isolating valve are fitted to the supply pipe to allow for easy servicing (see diagram below) or unit replacement, should the need arise.

Combining a corner shower surround with an electric unit makes for an instant shower in more than one sense, as you don’t need to build an extra wall to make the enclosure. The main advantage of a clear-glass surround is that it looks wonderful while letting in lots of light 1. The big disadvantage, though, is that it may take a bit of effort to keep it sparkling, especially if you live in a hard water area and you don’t have a water softener. If you squeegee the glass off after each shower, however, and train the rest of the family to do the same, you can reduce the major cleaning work considerably.

Water and Electricity Supply
1. separate circuit from consumer unit 2. mains water supply 3. non-return valve 4. shower unit	5. ceiling-mounted double-pole isolating switch 6. mains electric supply (via double-pole switch)

The flow of water through the shower unit triggers a switch to turn on the element that heats the water as it passes through. Because there’s so little time to heat the flowing water, a powerful electrical load is required, anything from 6-10.8 KW. This must be supplied by a separate radial circuit, protected by a 30 milliamp RCD 2.

The electric supply cable must be a minimum 10mm2 twin (two-core) and earth cable. The circuit needs a 45 amp double-pole isolating switch, which is usually a ceiling-mounted type as shown in the diagram opposite. The switch must have a mechanical on-off indicator as well as a neon one. It is also imperative that the shower unit and all metal pipes are bonded to earth. If you are in any doubt about the wiring requirements ask a qualified electrician to advise you. Indeed, you will almost certainly need to get an electrician to bring the new circuit for the shower from the consumer unit.

Once the electricity supply has been installed, fit a single 15mm (%in) pipe to bring water direct from the cold supply to the wall. Fix the shower unit to the tiled wall (see page 121 for fixing to tiles). With the power still switched off, feed the electric cable through the backplate of the unit and wire it up 3, following the manufacturer’s instructions. Join the water inlet pipe to the unit and tighten with a compression fitting 4. Fit the cover and attach the shower hose to the outlet at the base 5. Attach the shower head to the wall, high enough to avoid any back-siphonage 6.

Bathroom Tip: Buy a shower waste with a pull-out section so you can unclog the waste overflow regularly before a build-up of hair can cause blockage problems 7.

Related posts:

1. Choosing a shower