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Shower and undersink water heater.
Former Community Member
I have a property that has 6mm mains swa cable coming into the consumer unit via an RCD isolation switch. The home has a 7.2kw electric shower and I wanted to add a 7kw under sink water heater. So as to prevent overheating of the main cable and tripping of the main incoming fuse which is just 40 amps, could I put a 32 Amp 3 Pole Change Over Switch ahead of the two six mm cable wires which would be serving the shower and the water heater. Therefore negating overloading the main wire coming into the home by allowing only one of the appliances to be used at a time.
You could indeed have a simple change-over switch (a double pole or even single pole would do) - nothing electrically wrong with that. Might be a bit inconvenient for the user though - about to step into the shower and find the switch is in the wrong position...
The other approach is to automatically disconnect the water heater when the shower is in use - there are various load shedding relays available to do that, or they can come ready assembled as a "priority" unit - e.g. https://www.meteorelectrical.com/catalogsearch/result/?q=priority (just one example).
You could indeed have a simple change-over switch (a double pole or even single pole would do) - nothing electrically wrong with that. Might be a bit inconvenient for the user though - about to step into the shower and find the switch is in the wrong position...
The other approach is to automatically disconnect the water heater when the shower is in use - there are various load shedding relays available to do that, or they can come ready assembled as a "priority" unit - e.g. https://www.meteorelectrical.com/catalogsearch/result/?q=priority (just one example).
