New 10.5Kw Shower - Help please

[aw11star]

Hi,

I've had a 10.5Kw Electric shower fitted but the electrician has only wired it directly to the Consumer unit. It was meant to be like this temporarily, but i'm not having him come back to finish off as the job so far was not done very well.

So to sum up - 10.5Kw shower wired to Pull switch with new 10mm cable then wire to consumer unit also with new 10mm cable. The cable is partly in conduit face fixed to wall and partly ran through the joists.

The Consumer unit is an old type Wylex, brown plastic with plug in type re-wireable fuses, the shower cable is wired directly into a 30a cartridge on the CU.

I've tried the shower on full power for 30mins and the 30a fuse hasn't blown - even though a 45a fuse is recommended for this shower.

So question is

Yes I know I need to replace my CU, the house actually requires a re-wire at some point (about 50% of circuits are in old rubber cabling) but I wasn't planning on doing this until christmas as I'm planning on running the cabling myself and then getting an electrician to sort CU and loose ends.

Will It be safe if I simple put a 45a MCB and carrier into the current CU or do I need to fit a separate shower CU?

If i need to fit a separate shower CU (the combined RCD with 40a MCD type) can I connect this inline between the main CU and Shower pull switch - I.e. split the 10mm cable from the Main CU and wire it into the Shower CU?

I know I may seem tight but I've been stung by the last Electrician and being as i'm going to do a re-wire shortly I don't really want to pay out for something that will be redundant shortly.

Another thought I had was to buy a new CU and use that Inline of the old one (on the shower circuit as above) and run the shower through that until I get the rewire done.

Cheers

Any advice would be much appreciated.

 

[flameport]

The Consumer unit is an old type Wylex, brown plastic with plug in type re-wireable fuses

The shower should never have been connected to this at all - even temporarily. The correct way would be to install a small additional CU for the shower.

Will It be safe if I simple put a 45a MCB and carrier into the current CU

No. It is very unlikely that the fusebox you have will accept devices above 30A, and even if it did, there is no way to add an RCD to that kind of fusebox.

You should not use the shower at all in its current state - it is not safe, and there is no way to make it safe with the old fusebox you have.

If i need to fit a separate shower CU (the combined RCD with 40a MCD type) can I connect this inline between the main CU and Shower pull switch

Another thought I had was to buy a new CU and use that Inline of the old one (on the shower circuit as above)

No. You cannot connect the shower or any additional CU to the existing fusebox in any way.

Given the state of your other wiring (rubber cables etc.), fitting a complete new CU and connecting the old circuits to it is NOT an option. Not much point in buying a small shower CU either, since it would be redundant once the rewire is done.

If there is space, one option is to fit a new CU with space for all of the planned circuits, and connect the shower to this. When the other circuits are rewired, they can be connected into the new CU, and once all done, the old fusebox can be removed.

You will also need to have a double pole isolator fitting after the meter, both so the new CU can be connected to the supply, and to provide a single point of isolation while you have both the old fusebox and new consumer unit in use.

All of this is notifiable work (Part P).

 

[mikethesparky]

Hi aw11star,

Firstly by the sounds of things i would get on with that rewire as soon as possible, especially if you running on rubber. as a quick fix i would definatley change to a 45A cartridge MCB. when you rewire it will go on the RCD side of a split load board it will not need its own CU, if you wanted to fit a seperate rcd unit you could fit one in the 10mm circuit as suggested but its not best practise, usually you would double up the incomming tails in a henley block which would give your shower its own mini CU. you could however if you have the room, while were knockin ideas about, have another more reliabe sparky come and split your tails and fit you a new split load CU next to your wylex. Run the shower off the new one, then as you rewire your new circuits they can be added to the new CU until you old one is redundant then throw it off a cliff....

lots to think about there, hope it helps a little.[/img]

 

[mikethesparky]

sorry if i repeated what was said above i hasd lunch mid way and didnt read flameports answer.

 

[ericmark]

The question is "can I" and by the fact you have already employed an electrician I can assume your not qualified so all this work will come under Part P and the only person who can answer the question "can I" is the local authority building inspector.
If rephrased to "can the following be done" then yes most likely but first one would need to view the installation certificate issued by the first electrician to know what routes etc.
10mm cable does not have a fixed current rating and may be only rated at 32 amp if reference method 103 is used so until one knows all the facts no one can answer your question.
If your running cables then you will have already declared your intentions to LABC who then become responsible for site safety and as such you should ask their advice as otherwise you could so easily be required to rip it out and start again. You will need to declare the route and indicate the method of installation for all cables and they will need inspecting at various stages. If you have not already done so then do down load the Part P document.
If your is Scotland then there are stricter rules which I can't help with.
Eric

 

[ericmark]

flameport answer only appeared after I posted mine all he says is true and reinforces what I was trying to say which is it is all Part P and you are unlikely to be able to do anything yourself.
Do ensure the electrician used is registered that means he can sign the building control completion certificate it is your responsibility to ensure Part P is complied with. If an electrician says he is Part P and isn't you have redress but if he does not claim to be Part P registered it is your responsibility to inform building control as with many builder an electrician who is not registered may do it all for you but responsibility is still yours.
With the state of your house as described I would expect an all or nothing approach and any good electrician will either want to do complete rewire or will walk away his registered status is too important to take a risk and you are only likely to get poor electricians interested in part job and as a result your very likely to be ripped off.
It is now very easy for the rouge trader as if you break the law he knows your unlikely to report him for bad workmanship. Like stealing off a thief. If he can persuade you to brake the law by not declaring the work under Part P he knows he is safe and and bodge and run.
Eric

 

[aw11star]

Gents,

Thanks very much for all your responses.

Hate to admit it but appears I have genuinely been ripped off! Basically I've been charged £300 just to run a cable from under the stairs to the bath room (small 3 bed semi).

This guy is NICEIC registered but supposed to be a mate, guess he thought he was doing me a favour doing half a job (don't need friends like that).

Cheers

DEC

 

[Pensdown]

This guy is NICEIC registered but supposed to be a mate, guess he thought he was doing me a favour doing half a job (don't need friends like that).

Cheers

DEC

He may well be NIC registered but unless he's also NIC registered as a Domestic Installer he can't sign the work off.

 

[ban-all-sheds]

The Consumer unit is an old type Wylex, brown plastic with plug in type re-wireable fuses, the shower cable is wired directly into a 30a cartridge on the CU.

How else should it be wired?

What was temporary about it, and what were the planned changes when it was going to be made permanent?

I've tried the shower on full power for 30mins and the 30a fuse hasn't blown - even though a 45a fuse is recommended for this shower.

The type of "30A" fuse you have will pass 54A indefinitely, and up to 60A for over an hour....

I'm planning on running the cabling myself and then getting an electrician to sort CU and loose ends.

It doesn't work like that.

If i need to fit a separate shower CU (the combined RCD with 40a MCD type) can I connect this inline between the main CU and Shower pull switch - I.e. split the 10mm cable from the Main CU and wire it into the Shower CU?

Apart from giving you an RCD (which is worthwhile), what would that do to fix the possible overloading of the CU that you've got?

Another thought I had was to buy a new CU and use that Inline of the old one (on the shower circuit as above) and run the shower through that until I get the rewire done.

Ditto.

 

[ban-all-sheds]

You should not use the shower at all in its current state - it is not safe,

In what way is it not safe?

 

[ban-all-sheds]

Do ensure the electrician used is registered that means he can sign the building control completion certificate it is your responsibility to ensure Part P is complied with. If an electrician says he is Part P and isn't you have redress but if he does not claim to be Part P registered it is your responsibility to inform building control as with many builder an electrician who is not registered may do it all for you but responsibility is still yours.

Really?

How do you reconcile that view with the number of times the Building Regulations use the phrase "the person carrying out the work", or a variant thereof?

Or with the number of places where it talks about the need to notify being waived if the person carrying out the work is a member of one of the list of self-certifying schemes?

Or with the fact that the Building Regulations Explanatory Booklet says "The primary responsibility for achieving compliance with the
regulations rests with the person carrying out the building work."?

If it doesn't comply then the householder is the one left holding the baby, but it is not his responsibility to ensure that it does.

 

[flameport]

Not safe, because 45A through a 30A fuse will result in something like this, or worse.

 

[electronicsuk]

You should not use the shower at all in its current state - it is not safe,

In what way is it not safe?

Surely you're not saying that it's a good idea to intentionally overload a rewireable fuse? Bear in mind that the fusewire is going to get very hot when running at near its full capacity.

EDIT: Beaten to it! A picture speaks a thousand words, as they say. That is, until you look at the brand of the CU...