garage supply and rcd protection

[tawraste]

hi all,
could you please advise me on the following?

assume a small consumer unit in an outbuilding, connected via swa cable to the main consumer unit, and supplying a simple light circuit and a ring with 3 double sockets.
now if the whole thing has an rcbo at the main consumer unit, do you then need to put another one in the garage? and after that do you need to put rcbos or rcds on the small circuits themselves?

for instance,

45A rcbo at the main cu followed by 40A rcbo in the outbuilding, followed by a 32A rcbo for the sockets and a 6A rcbo for the lights.

surely this is rcd protection gone overboard? let alone very expensive!

cheers !

tawraste

 

[One_of_them]

no

RCBO at main CU

or depending on method of install regarding SWA, you could do away with RCBO at supply end and just fit in the garage as upfront RCD. As if the garage is far away, walking all the way back to the house to sort a tripped RCD/RCBO could be a pain in the rear

 

[tawraste]

cheers sparky,
i'm getting myself all mixed up with the requirement to rcd protect sockets and to provide discrimination! still studying hard, still getting confused!
that does make sense to me though, thank you.