Sub main advice please

[Matthew]

First post!!!

Very newly qualified so please bare that in mind!!

Recently converted a garage alongside a builder friend. Garage/living annex now has been wired with RFC one lighting circuit. Havent installed yrt but electric underfloor heating and towel radiator (small shower room)
Now what are your thoughts and please explain so i can learn!
I have run 16mm cable from house to garage but nothing connected. I was going to Henley block incoming tails to feed a new CU at house end and new CU garage end. OR could I/ what is stopping me connecting 16mm to current house CU thus preventing installing a new CU off split tails?
Thoughts gratefully recieved

 

['mr2'gd4u]

That's sounds fine, you could send straight to current cu but depends what you already have in your cu. My pref. Would be to fit to new supply like you said. If its more than 3m from supply to cu I'd fit an isolator at the Henley.

 

['mr2'gd4u]

Also the usual.. "get an electrician in to do it/check test and insp." there... I said it lol

 

[Matthew]

Thanks - i am newly qualified but not registered with CPS so will be third party tested/inspected - just after peoples advice and experience

 

[Wilko]

Hi Matthew and Welcome.
Your 16mm cable - what is it, how long is it, how is it installed, how will it be protected? Bonding?

 

[Octopus]

What has your schemes technical support line suggested?

 

[Matthew]

Thanks - 16mm T&E clipped direct to 1st floor joist then SWA trenched to garage all in all approx 15m. Will be earthed via current earth block at CU

 

[Matthew]

Not contacted Tech Support as wanted ither peoples opinions and experience

 

[mhar]

16mm implies either a substantial load or a long length to allow for volt drop.
A 50A mcb in your house consumer unit to protect the cable will not really give any discrimination from the mcbs in your garage cu so the answer is usually to use a fuse, something like a 63A in a switch fuse isolator.
Do your cable calcs really dictate a 16mm supply? Maximum demand is usually significantly less than how the OSG advises how to calculate it. For some (high integrity) cus you may be able to get a fuse holder instead of an mcb and fit a 40A fuse. Do a search on here for 'maximum demand', real life experience is likely to be an eye opener.
I would suggest that a non rcd protected swa from the origin connected into a small rcd/rcbo board is what you would be looking for

 

[Pete999]

What has your schemes technical support line suggested?

The OP doesn't seem to have left any information in his profile, in which case it is very difficult to see what experience, qualifications or any Scheme membership he has.

 

[Pete999]

Thanks - i am newly qualified but not registered with CPS so will be third party tested/inspected - just after peoples advice and experience

Thanks Matthew.

 

[Wilko]

Thanks - 16mm T&E clipped direct to 1st floor joist then SWA trenched to garage all in all approx 15m. Will be earthed via current earth block at CU

Hi - not meaning to sound funny, but as a learning opportunity perhaps have a cup of tea and a read of Reg 522.6 section in relation to how you've run your cable. See if anything stands out .

 

[Matthew]

Cable is more than 50mm from top and bottom.

 

[Pete999]

Cable is more than 50mm from top and bottom.

From top and bottom of what Matthew?

 

[davesparks]

That's sounds fine, you could send straight to current cu but depends what you already have in your cu. My pref. Would be to fit to new supply like you said. If its more than 3m from supply to cu I'd fit an isolator at the Henley.

Why an isolator? It needs an OCPD not just a switch.