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Electrical consumer unit question

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Bellie 18 Sep 2017
A question for the electrical bods out there. I have an outbuilding about 15m away from the house. It has power from its own MCB on the board. The incoming cable goes into an old mini consumer unit in the outbuilding - basically a switch and 2 old style fuses (1 32A, 1 6A) which powers the mains side and lighting in the outbuildings.

It needs replacing now. But my question is - does it need its own consumer unit or as it is already fed from a fused connection from the house should I just replace the old unit with a junction box to create the continuation for the 32A circuit and a fused spur to drop the lighting down to 6A that way.

I cant see the need for the extra consumer unit- unless the distance from the house is the issue.

The 32A mains then trundles off another 20m to a further consumer unit in the barn too.

Any help appreciated.
 Philip 18 Sep 2017
In reply to Bellie:

You need something, and a small consumer unit is probably the neatest way of downsizing the cabling + protection for circuits. Depends how simple you wiring is. A little CU gives you flexibility for the future.

https://www.tlc-direct.co.uk/Products/MK5704SSP1.html

£40 for this little CU.
 arch 18 Sep 2017
In reply to Bellie:

My shed is fed from the sockets in our Garage.

4 double sockets and a 5' Fluro spured off the sockets circuit with a switched fused spur with a 5amp fuse in it. The sockets are rarely used. Works for me, but it wont please the UKC/H electrical police.
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Bellie 18 Sep 2017
In reply to arch:

Yes, I'm thinking my incoming cable from the board into a double socket then a spur for the lights. The socket forms part of the ring main.

I can see the smartness of a consumer unit, but do wonder about the amount of trip circuits once I have a consumer unit in the barn too.

 arch 18 Sep 2017
In reply to Bellie:

> Yes, I'm thinking my incoming cable from the board into a double socket then a spur for the lights. The socket forms part of the ring main.

Its load at the end of the day. You could have a lamp on a plugtop into a socket, same thing really.

 DancingOnRock 18 Sep 2017
In reply to Bellie:

What size cable is on the 6A lighting circuit? Do you really want that cable/circuit backed up by a 32A breaker?
 GrahamD 18 Sep 2017
In reply to Bellie:

When you come to do work on the outbuilding, I think you'll regret not having at least some capability of isolating and protecting individual parts of the system . Our outbuilding is similar, with a very small old school ECU in place. Incidentally why do you think it needs to be replaced ?
Bellie 18 Sep 2017
In reply to DancingOnRock:

Its 2.5 t & E and would be off a 6A Fused unit. Are you saying that it would be better to be off a 6A breaker instead? I'll easily get one put in if thats the case - if dasiy chaining breakers isn't an issue.


Bellie 18 Sep 2017
In reply to GrahamD:

Its the on/off switch in it, getting to the point where it feels like its not opening breaking properly. Recently the power in that section has been going off, and only comes back on once I've done a switch back and forth. Time to get updated - along with my wiring.
 krikoman 18 Sep 2017
In reply to Bellie:

I'd be tempted to fit a new DB (<£50) unless money is really tight, at least then you get some RCD protection, which from the sound of things you don't have at present.
 Kevster 18 Sep 2017
In reply to Bellie:

Several items being missed here.

RCD protection. Please get this if not already installed.
Earthing and earth stake, some view it as minor, but depends on your incoming supply and the what ifs are not minor, if they happen.

As a sparks, please be careful if you do it your self, not that you're meant to.....

Bellie 18 Sep 2017
In reply to Bellie:

Thanks all for the replies.

Yes the main board in the house has a RCD on it. I think I'll grab a new little consumer unit and stick that in. Then at least I'm starting as I mean to go on. I am replacing all the wiring in the outbuildings and sticking it all in conduit and sorting out new cable runs, so may as well. I have a spark coming to do the important bits so it will be a damn sight better than the state I got the place!

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 DancingOnRock 18 Sep 2017
In reply to Bellie:

> Its 2.5 t & E and would be off a 6A Fused unit. Are you saying that it would be better to be off a 6A breaker instead? I'll easily get one put in if thats the case - if dasiy chaining breakers isn't an issue.

Normally the lighting circuit would be on 1.5mm (it's cheaper and 2.5mm is overkill) and as you say it's fused with a 6A fuse so I'd swap it with a 6A MCB. Separate breakers means if something takes the MCB for the sockets out, you still have lighting.

The breaker inside the house feeding the outbuilding would be an RCBO.
 birdie num num 18 Sep 2017
In reply to Bellie:

The best thing to do would be to wire your shed in directly from the street lamp.
Bellie 19 Sep 2017
In reply to DancingOnRock:

Cheers. Yes, all my new lighting circuit is 1.5mm. This was the old one which I think just got done years ago with all the same stuff (it was a farm so if he got a job lot that would be it). If you wanted an idea of how not to cable a place - then the original wiring is a good example!

Consumer unit it is then.

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