Sorry in advance for a common post.

I've Googled and checked and it seems to be OK, but could somebody just
have a read through and confirm if the set-up below is as per the
regulations.

Old set up:
Remote brick built shed, originally wired up by a previous owner. Fed via
a 13 fused spur from the downstairs ring main and terminated in a two way
fused CU in the shed. Power use in minimum - occasional hand tool, LV
garden lights. Internal 13A socket accessible for garden use as required.

Proposed new set up:
3core 4mm SWA - earth is taken through the yellow wire - with the armour
sleeving bonded to the yellow wire at both ends.

Two way CU in the shed with mcbs and protected by integral 30mA RCD.
Sockets (probably three) in the shed, either as a ring main or as a radial
circuit, plus an external socket mounted externally on the shed wall for
garden use.
- 2.5mm T&E fed from a 16A mcb

Shed lighting plus external light
- 1.25mm T&E fed from a 6A mcb

In-house connection is to a 32A mcb on a split CU and is protected by the
integral 30mA RCD in the CU (there are two split CUs in the house, this CU
only feeds shower and outside lights, so if it trips it's not a problem).

SWA terminated in the shed and indoors in a metal knockout box using
suitable glands. Metal box is also earthed (I assume that a plastic box
could be used instead if required?)

6mm T&E is used to complete the circuit from the SWA to the CU at both
ends.

I realise that this means that the shed light will be lost if the RCD
trips in the shed. I could solve this by using a separate CU in the shed
for lighting only (I have a spare CU) or is this not permissible as the
light would still be lost if the 32A mcb tripped in the house CU?

An alternative would be to use the existing supply from the fused spur on
the ring main to feed a separate CU in the shed just for the lighting,
using a 5A fuse in the spur instead of the current 13A one. However, I
would have liked to have got rid of that cable altogether.

I assume that if a separate CU was used in the shed for the lighting, that
this would also require its own RCD?

Thanks

Roger
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