Electric supply to new annex

[Locum Sparky]

I'm converting my old garage into a two bedroom annex. At its nearest point it is approx 10m from main house.
I plan it to be all electric, UFH, electric shower, electric hot water, cooker.
Now, I think there are 2 ways of supplying power to the new annex:
1. Run 25mm SWA tails from henley blocks in the meter box, underground to the annex, and into a new consumer unit.
2. Expand the old consumer unit in the main house, and run the required circuit cables from there to the annex.

I would prefer option 1 with a new CU in the annex, but how long can tails be after the 100A service cut out?

Opinions/advice gladly received.

 

[richy3333]

No you cant do it that way, and 3m

 

[Vortigern]

Henley to switched fuse, then 25mm SWA from there to annex. I assume you did not mean SWA tails and that was a typo. Is it just bedrooms or beds. and kitchen lounge etc?

 

[Locum Sparky]

Henley to switched fuse, then 25mm SWA from there to annex. I assume you did not mean SWA tails and that was a typo. Is it just bedrooms or beds. and kitchen lounge etc?

It would be self contained 2 bedroom annex, kitchen, lounge.
Either Henley to switched fuse then 25mm SWA 10m long to new CU in annex.
Or, extend existing CU in main house to accommodate new circuits needed for annex (lights, power, shower, cooker).

 

[Dustydazzler]

I would do as already advised and take a 25mm SWA via a suitable switch fuse

Nice little 6 way Rcbo boarrd in the Annex

Job done

 

[Vortigern]

with the load of combined house and annex you may be above the switch rating in the house CU. I would usually separate them split at henleys. Nice and independent of each other as well. Depends on diversity allowances.