Shower cable size question

[Robster_1981]

Hi
Apologies if this has been covered many times.

I'm fitting a triton shower at my girlfriends (i think it's 8 or 8.5kw) and bought some 10mm cable with a 30a fuse for the consumer box and 45a double pole pull switch.

I didn't buy enough cable for the job, but have some 6mm left over from something else.

Question is, is it ok to run 10mm from consumer to switch, then 6mm from switch to shower? also, is the 30a fuse adequate? (it's an old consumer with the two pin fuse's)

Cheers

 

[davy_owen_88]

Right, I'll start by informing you that this work is notifiable so if you haven't informed your BCO then do so BEFORE you start.

Another, far better solution is to get a registered electrician to do the work for you. No offence but fitting a shower is not a job for DIY'ers.

8000W / 230V = 34.78A
8500W / 230V = 36.97A

So no... A 30A fuse is not sufficient.

Are you aware that showers should be RCD protected? I doubt you have an RCD fitted if you have an old consumer unit.

Are you sure all supplementary bonding is up to scratch?

What length cable will you need to go from the switch to the shower?

Davy

 

[Mighty Quinn]

Right, I'll start by informing you that this work is notifiable so if you haven't informed your BCO then do so BEFORE you start.

Another, far better solution is to get a registered electrician to do the work for you. No offence but fitting a shower is not a job for DIY'ers.

8000W / 230V = 34.78A
8500W / 230V = 36.97A

So no... A 30A fuse is not sufficient.

Are you aware that showers should be RCD protected? I doubt you have an RCD fitted if you have an old consumer unit.

Are you sure all supplementary bonding is up to scratch?

What length cable will you need to go from the switch to the shower?

Davy

What he said. Also supplementary bonding to take into consideration. I'm not paying £400 a year whilst DIYers hoy any old crap in

 

[Steve]

Aye your girlfriend needs to update the fusebox to a consumer unit with RCD protection, before you fit this shower. Those old things were never designed with loads over 30 amps in mind.

There's also the liability issue. If the shower you fit blows up, kiss goodbye to your girlfriend and the settlement for damage to the house . . . Of course electricians have liability insurance for the money side of things.

then there's part p. This work is very notifiable to your local building control, as you are creating a new circuit and working in a bathroom and working in the consumer unit! Not notifying and paying their fee is against the law, and could be shown as negligence on your part, should anything go wrong in future, thus re-inforcing any settlement claim made against you.

Sorry to go all legal on you, but this had to be said. Dont do it.

 

[Robster_1981]

There was an electric shower in our house when we moved in (unknown rating) but we have an old consumer unit and it was running on a 30a fuse and we had no problems at all in the 2 years we had it.

Also, just to satisfy my curiosity, wouldn't the fuse just blow if the current was too high?

I take your comments on board, and thank you, I am just trying to confirm what i am thinking

 

[davy_owen_88]

There was an electric shower in our house when we moved in (unknown rating) but we have an old consumer unit and it was running on a 30a fuse and we had no problems at all in the 2 years we had it.

Also, just to satisfy my curiosity, wouldn't the fuse just blow if the current was too high?

I take your comments on board, and thank you, I am just trying to confirm what i am thinking

The old shower worked because it was obviously of a lower rating, somewhere around 7kW.

If you fit the shower you intend to the fuse you intend then the fuse would 'just blow' when you start using the shower.

Davy

 

[sm1thson]

Robster_1981, dont take offense at the sparks trying to put you off. note they did point out that you can do this works, its just by law you have to inform building control. and that aside there is the safety issues, the supplementry and main boding both need to be up to scratch -you can do these within the scope of the law. an RCD is essential where water and electricity may mix. it looks like you are clearly going to go ahead anyway, if this is the case you need to sit back and do some more reading first and do the job properly, your name and your girlfriends life are on this now! just because there wasnt an RCD before doesnt mean you /she will be so lucky nexttime.

 

[Steve]

dont forget to update that fusebox too

 

[Robster_1981]

Thanks again for the comments!!

Can an RCD be fitted to an old CU? i'm now having doubts when i was at first so confident
The big problem we face is cost, and fitting a new consumer unit is not within our budget at the moment, so is it possible to fit this shower safely with the existing CU?

Cheers

 

[breezer]

probably not.

but to be sure post a pic

pic info is in forum information

 

[RF Lighting]

You could fit a new 1 way CU just for the shower.

They are only about £35

 

[Robster_1981]

You could fit a new 1 way CU just for the shower.

They are only about £35

Something like this?

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A332309&ts=46636&id=29659

 

[Steve]

Yep. Oh look, its a Crabtree too!

But then you have the complication of connecting it to the meter tails.

 

[breezer]

you just beat me to it.

i will also sosay, sorry its NOT a diy job

 

[Robster_1981]

What have i got myself into! she's going to kill me if i say i cant do it it's all plumbed up too