On 01/05/2019 07:33, wrote:
The 6mm2 cable runs from the back of the consumer unit through a
double skin wall straight into a ceiling-floor void for 2.5m and then
straight through a double skin wall. The cable is then direct
clipped on the wall at a height of 2.5m towards the garage door, past
the garage door and then along the opposite side wall.

In which case you can probably argue that a deviation is acceptable, and
feed the T&E from a non RCD protected B32 MCB.

There will be a cooker switch style isolator which is how the 6mm2
cable will connect to the 10mm2 SWA.

ok

I cannot see a situation where a rcbo is required in the house
consumer unit....

Technically speaking, all cables should now have RCD protection unless
they are mechanically (or otherwise) protected from damage. Surface
mounting is in some cases an acceptable way of protecting it (i.e. you
are less likely to drill into it etc).

The SWA is then buried under lawn before coming out into metal shed
to feed the second consumer unit.


--
Cheers,

John.

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