new shower circuit in old CU

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Hi, need some advice regarding a new MCB for a shower.

I am installing a shower and have a spare MCB (15A) on the CU that I would like to replace with a 45 A MCB. Is this a fairly straight forward task, i.e.. turning off the main switch of the CU, removing existing MCB and then replacing with the new one. I understand that the 45A MCB would need to be closest to the main switch. Is this a case of just moving the other MCB's along and putting the 45A MCB in its respective place?

Any help would be appreciated.

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Lots of people will be along in a moment to check that you really know what you're doing.

You mention a shower - what power rating is it, and has the cable been installed for it yet?
 
Its an 8.5kw Triton. Cable is in place. 10mm. Over all length about 9m from shower. This goes from shower to CU via 45A Pull Cord switch...sorry for late response
 
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He mentions a 15A MCB (not 16A).

I'm guessing old push-button Wylex. Predates split load.

Can you post a picture?
 
Since your shower will draw no more than 36A (if rated at 240V), a 40A MCB would be better suited.

Before adding this to your CU you should ensure that the CU can take the entire load from all the circuits.

If the new shower circuit won't be protected by an RCD, it would be safer to (a) add an extra CU and connect the shower circuit to that, or (b) use an RCBO instead of an MCB, or (c) reconfigure the CU (with substantial testing afterwards) to split the circuits and put the shower on an RCD protected section.

The new shower circuit is also notifiable work, so unless the person installing it is a self-certifying electrician, you need to tell your LABC before work starts.

Whatever you do, you'd also be well advised to carry out proper testing of the new circuit before energising it.
 
Many thanks, all the information I need. Now does anyone know how to build a brick wall?! :LOL:
 
Of course. What you do is say to a brickie: "please build me a wall over there".
 
Last item you need. Check the label on your existing fuseboard. it may say "maximum load 60A" in which case you may be overloading it.

Aren't there regulations governing who can do this sort of work in Renfrewshire?
 
Taylortwocities said:
Last item you need. Check the label on your existing fuseboard. it may say "maximum load 60A" in which case you may be overloading it.
For some reason I thought I'd covered that one. :confused:

Aren't there regulations governing who can do this sort of work in Renfrewshire?
Well, there aren't any in England or Wales either.
 
jjoja said:
Sorry I have no picture at the moment as the shower is in another property.

I suppose this is a rented flat with amateur electrical work in it?
 

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