10mm T&E to 6mm T&E

[farqu01]

Hi

I have recently had a bathroom replaced which had an electric shower, this was changed out for a mixer shower off the combi boiler.

The shower cable is a 10mm twin and earth which was pulled back to loft space and JB'd.
A 40amp cb fed the shower.

I am wondering if it is ok run a 6mm supply to my garage, tying into the above JB with the 10mm cable?

There will be a garage consumer unit installed which has a 40amp 30ma rcd, 32amp and 6amp cbs fitted.

The 10mm cable appears to be a horrendous,tight run hense reason asking if ok to utilise jb for supply.

Thanks

 

[ipf]

Of course all depends on garage location, cable length, type and route.

Exactly. What are the odds in a domestic situation? Presumptuous, to say the least, to leave it at 40amp.

Think what you like but I wouldn't be installing a T+E without rcd, sub feed or not.

 

[ipf]

Also to add, if you can get an 32A RCBO to fit your current CU so it has independent RCD protection from the house circuits then you could feed the T&E from that and simply omit the RCD in the garage CU if you want.

Two 30mA RCD in series won't be selective on a fault, but it is not in any way dangerous, just mildly inconvenient to have to check and/or reset both after some trip. Had the feed been inaccessible by the folk using the garage then it would be a whole lot more trouble and a better planned installation worth doing (e.g. SWA cable so no feed RCD necessary).

Plenty good points in both posts.

I think we're getting a bit involved for a DIY job, though.

It'd be a bit more interesting to see the 10mm JB arrangement in the attic.

 

[farqu01]

Ok thanks for the replies it is appreciated.
Garage is

So just to reflect

Exactly. What are the odds in a domestic situation? Presumptuous, to say the least, to leave it at 40amp.

Think what you like but I wouldn't be installing a T+E without rcd, sub feed or not.

Ok thanks for the info guys.

So what do you rekon of this then?

Change 40amp breaker for 32amp.
Use 6mm ties into 10mm via junction box then out to garage.
Keeping 32 amp breaker rcd side in house cu?

Is that workable or will i just bite the bullet and run my new 6mm cable end to end approx 20 meters. garage is attached to house so no out side cable run?

 

[pc1966]

If it is all "indoors" as an attached garage then go with the physically easier option of the 10mm-6mm join and keep it on the RCD side with a 32A breaker.

Make sure you have a proper JB that will take 10mm though. Something like this:

60A Junction Box 3 Terminal White

A selected range of special purpose moulded and stainless steel accessories

www.cef.co.uk

 

[timhoward]

Just to comment that I wasn't thinking enough about the original 10mm length when I posted above, I'd got idea it was all ref method C for some reason which as fairly stated is highly unlikely. Sorry for confusing matters.

 

[littlespark]

There’s quite a few of us in Scotland if you need an “eyes on” recommendation.
but I see nothing wrong with what’s been proposed so far.

 

[ipf]

If it is all "indoors" as an attached garage then go with the physically easier option of the 10mm-6mm join and keep it on the RCD side with a 32A breaker.

Make sure you have a proper JB that will take 10mm though. Something like this:

60A Junction Box 3 Terminal White

A selected range of special purpose moulded and stainless steel accessories

www.cef.co.uk

With there being a 10mm T+E, maybe a 50amp Crabtree oblong 4500 DP switch in the attic.

 

[Petej999]

Hi

I have recently had a bathroom replaced which had an electric shower, this was changed out for a mixer shower off the combi boiler.

The shower cable is a 10mm twin and earth which was pulled back to loft space and JB'd.
A 40amp cb fed the shower.

I am wondering if it is ok run a 6mm supply to my garage, tying into the above JB with the 10mm cable?

There will be a garage consumer unit installed which has a 40amp 30ma rcd, 32amp and 6amp cbs fitted.

The 10mm cable appears to be a horrendous,tight run hense reason asking if ok to utilise jb for supply.

Thanks

What KW is the shower??

 

[Petej999]

What KW is the shower??

IGNORE please didn't read the bit about the boiler

 

[littlespark]

You can edit your most recent posts, pete

 

[AJB Temple]

Personally I would fork out for a bit of 10mm, which for that amount will not be super expensive, and keep it all the same.

 

[loz2754]

After almost a year I suspect it's all been sorted by now...

 

[AJB Temple]

Ooops! I only read this because I clicked on new posts and it popped up. Apologies.