Adding a consumer unit

[towman]

Apologies - I know some of this has been done before but finding it all and summarising isn't that easy !

I'm thinking of having some electrical work done to add sockets to a conservatoty and garage. Conservatory would be 4 doubles and garage may in the future be converted to office/utility - it currently houses tumble dryer etc.
I'm thinking that it would be better to look at worst case scenario - could be a couple of heaters on in the conservatory, tumble drier running, maybe some other stuff in garage too(or conversion if/when it gets done) so would be better to have 2 rings to supply garage and conservatory and a lighting ring too.
The meter and house CU are about 10m away on opposite side of house to garage and conservatory so I guess the easiest solution would be to split the meter tails at a Henley block. From there 1 set to present CU and 1 set to a fused isolator (60A?). SWA from the isolator to a second CU in the garage and rings running from that.
This seems a "better" and neater and more convenient solution than trying to run at least 6 cables from the present CU or trying to extend the existing ring to cover the conservatory and possible garage conversion.
I would be getting a "proper" electrician in to check on/do the work but would just like to know if what I'm proposing is OK - I'd rather not have to try and get cables all through the house and get a larger house CU to accomodate extra rings!
Thanks for any help/suggestions - of a polite variety

 

[plugwash]

cant see any real problem with doing that

probablly best to use a metalclad switchfuse and CU so you can terminate the armoured cable to them directly.

 

[felix]

This sounds like a well planned job. Only one possible problem comes to mind - how big is the fuse on your incoming supply? Let's hope that the electrician who does the job asks the same question!

 

[Damocles]

As felix just suggested, do you really need 30A in the conservatory and another 30A in the garage? Bearing in mind your house supply may only be rated 60A. Bearing in mind most houses would run without problem with every socket in the property running from one ring. Bearing in mind the best place for a separate ring is the kitchen as it is the most likely place to use lots of power at once.

Now isn't it a perverse lesson we have here. People build conservatories because they are exempted from building regs and planning. Then they use them as living space in winter, which is wholly not what they are designed for. And thus the law forces us to live in a freezing greenhouse wasting heat like crazy.

I think generally it would be better to keep all the CU in one place, so if there is ever a problem you only need to look in one place. Also a little ugly to have a CU on the wall of your office.

 

[plugwash]

it seems in nearly all cases the rec will uprate a service fuse to 100A the first time you blow it.

i agree that rating the submain at 60A is probablly overkill but it means if someone decides to fit say an electric shower they have the option of taking it to the second CU.

finally i just rembered you can get 16mm T&E which is fine for a 60A submain so if the run is inside theres no need to use SWA

 

[towman]

Thanks for your help and advice - you were right - supply fuse is 60A - I'm hoping REC will uprate it when I have the isolator fitted in VNF.

60A (14.4 kW)seems a bit light nowadays ? It wouldn't take many appliances to push that surely? Thinks - WMC 2.5 kW, TD 2.5 kW, DW 2 kW,mwave 1.5 kW,oven 2.5 kW,electric shower 8 kW etc - and yes I can forsee plenty of cases where all those things could be on at once - and I haven't included immersion heater etc? (granted that not all these loads are constants) but there doesn't seem to be a lot of capacity left?

Point taken about conservatory use - if I could afford a proper extension that was worthwhile I would !

There is a chance that a route for one large cable could be found internally - might have to go in surface conduit as a temp measure. Having a small CU elsewhere not a problem for me - no uglier than the current one sited in the hallway!
Cheers again - Towman