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  • Replacing MCB's with RBCBO's in old Crabtree box?.

    From tony sayer@tony@bancom.co.uk to uk.d-i-y on Tue Sep 22 23:51:36 2026
    From Newsgroup: uk.d-i-y


    Offspring has a small house that has the consumer unit under a worktop
    in a very awkward position to get to and it seems to be recessed into
    the wall.

    Said box has a main 100 amp switch and around 5 or 6 MCB's.

    We'd very much like to add in RCD protection but there isn't room.
    Assuming that a RCBO would physically fit in the MCB's place is that
    permitted at all?, anyone done that?

    TIA..
    --
    Tony Sayer


    Man is least himself when he talks in his own person.

    Give him a keyboard, and he will reveal himself.


    --- Synchronet 3.22a-Linux NewsLink 1.2
  • From John Rumm@see.my.signature@nowhere.null to uk.d-i-y on Wed Sep 23 03:01:43 2026
    From Newsgroup: uk.d-i-y

    On 22/09/2026 23:51, tony sayer wrote:

    Offspring has a small house that has the consumer unit under a worktop
    in a very awkward position to get to and it seems to be recessed into
    the wall.

    Said box has a main 100 amp switch and around 5 or 6 MCB's.

    We'd very much like to add in RCD protection but there isn't room.
    Assuming that a RCBO would physically fit in the MCB's place is that permitted at all?, anyone done that?

    It is acceptable to replace a MCB with a RCBO. However finding one that
    will fit an old CU might be a challenge.

    Could one relegate the existing CU to function as a switch fuse, and
    feed a submain to a new CU sited somewhere better?
    --
    Cheers,

    John.

    /=================================================================\
    | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------|
    | John Rumm - john(at)internode(dot)co(dot)uk | \=================================================================/
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  • From tony sayer@tony@bancom.co.uk to uk.d-i-y on Wed Sep 23 19:01:53 2026
    From Newsgroup: uk.d-i-y

    In article <118vbu6$1c5p9$2@dont-email.me>, John Rumm <see.my.signature@ nowhere.null> scribeth thus
    On 22/09/2026 23:51, tony sayer wrote:

    Offspring has a small house that has the consumer unit under a worktop
    in a very awkward position to get to and it seems to be recessed into
    the wall.

    Said box has a main 100 amp switch and around 5 or 6 MCB's.

    We'd very much like to add in RCD protection but there isn't room.
    Assuming that a RCBO would physically fit in the MCB's place is that
    permitted at all?, anyone done that?

    It is acceptable to replace a MCB with a RCBO. However finding one that
    will fit an old CU might be a challenge.


    We'll get one from TLC and see how it measures up:)



    Could one relegate the existing CU to function as a switch fuse, and
    feed a submain to a new CU sited somewhere better?


    If it were that simple but it'd need a kitchen refit, not a lot of room
    there let alone awkward to get to!..
    --
    Tony Sayer


    Man is least himself when he talks in his own person.

    Give him a keyboard, and he will reveal himself.


    --- Synchronet 3.22a-Linux NewsLink 1.2