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[Lefty]

Following installation of solar water heating, I am removing an electric (3.8KW) shower and replacing it with a mixer shower fed directly from the hot and cold tanks. Because the head of water is only about 800mm, I also intend to install a twin impeller shower pump (in the airing cupboard).

I will be disconnecting the power supply to the old shower back to the isolation switch in the airing cupboard, but will need a supply to the pump and there is no ring main socket in the vicinity to spur from.

Currently the shower is on a separate 40 amp RCD. Could this be downrated and the existing wiring be used to supply the pump or does a new spur HAVE to be taken from a (distant) ring main socket ?

[Gloucester Sparky]

Yep…. that’s fine.

As you said you will need to down grade the fuse at the consumer unit and use the old isolation switch ( pull cord I presume ) as both a junction box and isolation point.

If you now find that you have no RCD protection then replace the pull cord with an RCD FCU

Good luck with the pump they can be a bit noisy ( more noticeable at night )

Whilst you are at it, it would be a good time to bring your supplementary bonding up to date

Hope this helps

Gloucester Sparky

[Lefty]

Thanks, that's really helpful. Do you mind me asking what you mean by 'supplementary bonding' ?

[thedoctor]

If you are working on a special area circuit (bathroom) you need to get the work carried out by an electrician qualified to do so under part P of the building regulations. This is enforcable by law.