30amp to 45amp

[jazzy1963]

Hi all
I have a 10.5kw shower, which has the correct width cable and the isolating switch, but it kept blowing the "30"amp fuse!!!. I blew 3 fuses over a few weeks before I realised my stupid error.

My question is now that I have got a 45amp fuse(which of course won't fit in the fuse box) is it a hard job to replace the fuse fitments/box, or is it just a case of turning off the power disconnecting the old one and fitting and connecting the new box?

And is it possible to just change the 30amp insert and replace it with a 45amp insert and plug it in to the present fuse box fitting.

Hope this makes sense

Thanks for any help Geoff

 

[sparkyspike]

If you're talking about Wylex rewireables then yes you can change the 'inserts' for the correct colour for the new fuse. BUT you need to know a few things.

Do you have RCD protection for the shower circuit?
Is the cable rated for a 45A rewireable fuse, taking into account length and installation method?
Do you know this is notifiable work and you need an installation certificate?

 

[electronicsuk]

Hi all
I have a 10.5kw shower, which has the correct width cable and the isolating switch, but it kept blowing the "30"amp fuse!!!. I blew 3 fuses over a few weeks before I realised my stupid error.

The correct 'width' cable? We measure cable sizes by Cross Sectional Area, so when we specify, say, a 10mmsq cable, this is referring to nothing other than the area of the copper conductors themselves. If your old circuit was 30A then it's very likely the existing cable is too small to support your new, larger shower,

My question is now that I have got a 45amp fuse(which of course won't fit in the fuse box) is it a hard job to replace the fuse fitments/box, or is it just a case of turning off the power disconnecting the old one and fitting and connecting the new box?

No, sadly it's nowhere near as simple as that, and not really a DIY job unless you have some idea of what you're doing and notify your local BCO before commencing the work, along with paying their notification fee.

Unless you have a DP isolator fitted after your meter, you would first have to contact the DNO to have them pull your service fuse, after which you'll be without electricity until the job is completed. You will then have to make sure your main bonding to incoming gas, water and any other services you have is up to scratch. You'll need to make sure that your meter tails and main earth are the correct size. Existing circuits will need to be tested and inspected to ensure they're suitable for connection to the new CU. You'll need to know what to install in order to comply with the 17th edition wiring regulations. And then some.

And is it possible to just change the 30amp insert and replace it with a 45amp insert and plug it in to the present fuse box fitting.

No, a Wylex standard board is not really suitable for such large loads, and it's unlikely you have the necessary RCD protection.

 

[Chri5]

I'll ask the logical question.

If you believe the cable is the correct size (10mm dependent on installation method and length of run) why would it have been fused at 30a?

I'd suggest it's a 6mm and that your prognosis isn't correct regarding cable size.

Whatever it is- you will need to seek the services of a professional because the likely work is illegal as a DIY and you wouldn't want any nasty incidents due to incorrect installation and lack of correct testing and certification.

 

[Steve]

Wheres securespark with his photos of burnt out wylex rewireables from this very scenario?

 

[jazzy1963]

hi
The RDC is a pull switch about 3 meters away from the shower, the cable is approx 14mm wide so it must be a 10mm and it is a wylex connection.

I understand I will have to get a pro in to certify the work, I know for safety but also I'll have to ,to keep my insurance validated
Thanks for all your advice.

 

[Steve]

hi
The RDC is a pull switch about 3 meters away from the shower

No it isn't. A pull switch provides no automatic disconnection protection. It is a switch. Simple as. And an RDC is a regional distribution centre. An RCD is a residual current device, and could save your live. Telltale feature is a test button.

A fuse will not save your live. It takes 50mA to kill. A 30amp fuse is 600 times this. A 30mA RCD is a little bit less.

 

[RF Lighting]

Wheres securespark with his photos of burnt out wylex rewireables from this very scenario?

Will mine do?

These photos are the result of someone doing exactly what you are intending.

It is a 45A fuse in a wylex style fusebox.
This sets fuseboxes on fire. Alot.

Oddly enough this required a new fusebox to be installed. That is an expensive call out

 

[electronicsuk]

hi
The RDC is a pull switch about 3 meters away from the shower, the cable is approx 14mm wide so it must be a 10mm and it is a wylex connection.

I understand I will have to get a pro in to certify the work, I know for safety but also I'll have to ,to keep my insurance validated
Thanks for all your advice.

I'm not sure how you've come to the conclusion that a 14mm wide cable must be 10mmsq. In any case, it's irrelevant now as you've already stated that you'll be getting a pro in, he'll be able to provide all the advice you need.

Also, don't assume that you'll be able to do this work yourself and call in an electrician to certify. They aren't permitted to do this, only your LABC can certify DIY work. That's not to say that some electricians won't still certify it anyway, but they would need to be involved right from the start, and as you don't even know what an RCD is it seems unlikely you'd find an electrician willing to lend his name to your work.

 

[securespark]

Wheres securespark with his photos of burnt out wylex rewireables from this very scenario?

[pants heavily]

I came as quick as I could....you mean these in this thread?

//www.diynot.com/forums/viewtopic.php?t=152283

 

[ricicle]

I came as quick as I could....

Didn't interupt anything did we..............????????

 

[securespark]

OK, Finbarr!!

 

[RF Lighting]

I thought you'd been 'done'

 

[securespark]

 

[Spark123]

If you're talking about Wylex rewireables then yes you can change the 'inserts' for the correct colour for the new fuse. BUT you need to know a few things.

Not strictly true - a fuse above 30A will have a keyed base which will only fit certain boards in certain positions.