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Outbuildings - multiple consumer units

Former Community Member
Former Community Member
Evening all,


In a situation where I'm shortly going to be rewiring a new house I'm moving into and am hoping someone can provide me with some clarity on the best way to provide power to multiple outbuildings. 

Essentially I had planned to install a main consumer unit indoors and then feed the outbuilding via an RCBO on this consumer unit, i.e. consumer unit to, twin and earth, to junction box internal, to SWA across the garden, to secondary consumer unit in outbuilding - repeat this 2 or 3 times to the various outbuildings I need power in. However when doing a bit of research on the subject there seems to be differing opinions on whether to do this or to install a Henley block at the main incoming supply and then come out of that with one feed to my 'main consumer unit' and another feed out to the 'secondary outbuilding consumer unit' or multiple consumer units. It never occurred to me that this was an option and frankly I'm in a muddle as to what the consensus is on best practice, some mentioning a Switched fuse also.


If anyone could give me their opinion on what the safest and best practice is i'd be extremely grateful! TIA
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    There are pros and cons to both the henley block, and the breaker(s) in the CU approach.

    The obvious one is ease of isolation and if you want to turn the house of and leave the outbuilding on or vice versa.

    You must have some sort of fuse or breaker between the meter and the long run of cable to the outbuilding, but it does not have to be along side all the others. But note you should have a clear place for isolating the whole installation, ideally a single point.

    Total load also comes into it as well, if the outbuilding loads are more than a few tens of amps then you do not want them  eating up the capacity of the main CU. Depending on the layout you could feed one outbuilding from another, but this may not make sense if they are not in the same direction.

    More details may clarify some of this.

    Then there is earthing - do any of the outbuildings have water or gas supplies that would need earthing ? If so then you may need a 10mm2 earth bond.

    Or if they have earth floors or will supply things outside like a caravan or a car charger, you may prefer to make them TT islands.



    Mike.

Reply
  • 0
    There are pros and cons to both the henley block, and the breaker(s) in the CU approach.

    The obvious one is ease of isolation and if you want to turn the house of and leave the outbuilding on or vice versa.

    You must have some sort of fuse or breaker between the meter and the long run of cable to the outbuilding, but it does not have to be along side all the others. But note you should have a clear place for isolating the whole installation, ideally a single point.

    Total load also comes into it as well, if the outbuilding loads are more than a few tens of amps then you do not want them  eating up the capacity of the main CU. Depending on the layout you could feed one outbuilding from another, but this may not make sense if they are not in the same direction.

    More details may clarify some of this.

    Then there is earthing - do any of the outbuildings have water or gas supplies that would need earthing ? If so then you may need a 10mm2 earth bond.

    Or if they have earth floors or will supply things outside like a caravan or a car charger, you may prefer to make them TT islands.



    Mike.

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