Electric Showers Explained
Electric showers can be used within any domestic water system. They, in most cases, are connected to the mains cold water and an element within the shower heats the water as it passes through the unit. If you can arrange a clearance of 10 metres from your shower spray to the underside of the cold water tank, you can fit an electric shower to this. In this situation the shower must have an independent cold supply from the tank.
The water at your mains entry must have a running pressure of min 1 bar, must flow at a rate of 8 litres per minute and have a maximum static pressure of 10 bar. Most electric showers will be configured for these water bye law stipulations but it is as well to check with the manufactures instructions.
Your shower must be connected to the mains via a 15mm water pipe and it is just as well to install an isolation valve in this run. The valve can be turned off if and when maintenance is required to the shower and this removes the need for water to be turned off at the mains, disrupting all other water uses.
The electrical connections to an electric shower are covered by many regulations. An electric shower must be installed on its own circuit and not spurred from any other connections or appliance. First you must check that your fuseboard is capable of providing the current necessary and must be rated above 60 amps. An RCD (residual current device) must be installed as, either part of your existing fuseboard, or separately, interrupting the circuit to the shower. Connection to the fuseboard should be by means of a MCB (miniature circuit breaker). Fuse, switch and cable ratings are also vital and we would suggest that 10mm cable is used for all installations. This makes upgrading your shower much easier in the future.
Electric Shower Power Ratings and Power Cable Information
- Showers up to 7kw may carry a 6mm cable as long as the shower unit is within 18 metres of the fuseboard. Fuses and switches should be rated at 32 amps.
- Showers up to 9kw may carry a 6mm cable as long as the shower unit is within 18 meters of the fuseboard. Fuses and switches should be rated at 40 amps.
- Showers up to 9.5kw should carry a 10mm cable to units within 35 metres of the fuseboard. Fuses and switches should be rated at 45amp
- Showers up to 12.5kw should carry a 10mm cable to units within 35 metres of the fuseboard. Fuses and switches should be rated at 50 amps.
In all cases the circuit should be interrupted by a double pole pull cord switch with a neon on/off indicator and a mechanical indicator should the neon fail.
It is essential, in all cases, that the shower supply pipes are independently cross bonded to earth.
In all cases, please note this is for guidance only, please consult a Part 'P' registered Electrician.