While most showers are manually operated with gravity and the available water pressure, electric showers can provide several benefits in homes with low pressure or for those who simply want the latest in technology. Electric showers can be installed in conjunction with any domestic plumbing system.
There are a few factors that must be met before an electric shower can be installed. First, there must be a clearance of 10 meters from the shower head to the cold water source. The water at the source must also have a minimum running pressure of 1 bar with a flow of 8 litres per minute. The maximum pressure of the water with the valve closed is 10 bar. Almost every electric shower comes preconfigured for these conditions. Some can be altered for exceptional conditions.
There are several types of electric showers available. All of them hook up directly to the cold water mainline. Some of them connect to a water heater line and operate as mixer showers, while others heat water internally, so only the cold line is required. The cold line main pipe must be a 15 mm pipe to make a direct connection. It is recommended, however, to install an isolation valve between the mainline and the shower so it can be maintained without having to shut off the main water line, disrupting the use of all water in the home or in several connected flats.
It is recommended that the electrical connection for the shower be made by a qualified electrician to make sure all regulations are being met. The shower must be installed on its own circuit and cannot be linked to a circuit with other appliances. The circuit box must be rated for a 60 amp connection for the shower. In addition, a residual current device (RCD) must be installed either as part of the circuit/fuse board or separately on the circuit leading to the shower. The connection from the shower circuit to the board should be through a miniature circuit breaker (MCB). It is recommended that the circuit consist of a 10 mm cable. This will allow for future shower upgrades to be installed.
The following are the minimum wiring requirements for the most common electric showers:
The minimum cable width for a 7 kw shower is 6 mm, but the shower must not be further than 18 meters away from the circuit box. All fuses and switches must be rated for 32 amps.
An 8.5 kw shower within the 18 meter distance is also 6 mm, but the fuses and switches must be rated for 40 amps.
A 9.5 kw shower requires a 10 mm cable and can run up to 35 meters distance. Fuses and switches must be 45 amps.
A 12.5 kw shower also requires a 10 mm cable for up to 35 meters, but fuses and switches must be 50 amps.
For all electric showers, the supply pipes must be cross bonded.