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Topic Title: Moving/installing new consumer unit with old conduit earthing arrangement
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Created On: 06 August 2014 09:23 AM
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 06 August 2014 09:23 AM
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apj100

Posts: 57
Joined: 22 October 2009

Hi,

I have been asked to move a consumer unit in a house mid refurb. The old board is metal clad with the earthing being provided via conduit throughout. How would you go about relocating/installing a board with full RCD protection without extending all the conduit to a new metal clad board or requiring. Is it possible to extend the cables and then clamp onto each conduit and run an earth wire to the new board?

Thanks
 06 August 2014 09:39 AM
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AJJewsbury

Posts: 11462
Joined: 13 August 2003

Presuming it's modern threaded steel conduit rather than the old butt-seamed 1930s stuff, the best solution would of course be to extend the conduit and re-thread the cables to the 1st point on each circuit. It sounds like a very good quality existing installation and it would feel like a shame to 'downgrade' it to an ordinary T&E effort.

Patching something on the end of the existing conduit raises a few challenges... Presumably the customer wants the CU moved because they don't want electrical equipment at the original position - so say sticking in a steel box to terminate the conduit to and contain connectors for the wires presumably wouldn't be acceptable (likewise re-purposing the old CU case as a joint box). Any conventional clamps on the ends of the conduit would have screw connections, so would need to remain accessible - so can't be buried in the wall for instance. As ever, the devil is in the detail and the solution will probably depend on what compromises the customer will accept, so probably more detail needed.

- Andy.
 06 August 2014 12:05 PM
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BrucieBonus

Posts: 687
Joined: 20 February 2007

If the house is being refurbed are any changes being made to socket/light positions?

It will be pretty difficult to do this with the existing conduit as earth system and so rewiring the circuit with t and e is what generally happens.
 06 August 2014 12:42 PM
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eclipse

Posts: 149
Joined: 03 November 2006

Well providing the conduit is of a modern type, then why not use knock on conduit accessories,

-------------------------
Thanks

Alan.

Now what was that reg no?
 06 August 2014 01:29 PM
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mapj1

Posts: 2795
Joined: 22 July 2004

How far do you want to move it, and is the conduit sunk into in the wall or surface by it meets the old CU. If you really don't want to continue in more conduit or rectangular trunking, and it is a fairly long way to the new CU and not in a straight line, it might be easier to abandon the last few feet of conduit and connect on to the existing wiring either under the floor or at ceiling level. At that point any conduit box where you can fit some wago blocks and attach a CPC is in order, and then you can be into the cable of your choice.

Conduit is not constrained by concerns of safe zones and so forth, but anything you do that is not in conduit will be, and if the idea is to have a clear wall where the old CU was, it may then be awkward for future users to realise there is wiring there.
I think to advise better than generalities we need a bit more info.

-------------------------
regards Mike
 07 August 2014 10:59 AM
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peteTLM

Posts: 3152
Joined: 31 March 2005

Would that be METAL conduit is not constrained Mike...............:-)

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 07 August 2014 11:13 AM
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peteTLM

Posts: 3152
Joined: 31 March 2005

Really you should be looking at adding a cpc to all the affected circuits. If it is slip conduit, it will no longer be fit for purpose as a cpc.

If its old enough to not have a actual cpc conductor, how old is the cabling, hoe much longer will it go on for!?

The easiest way is to leave the back of the old consumer unit in place with all the conduits still attached, and make up a paxolin cover for the front of it. Use this as a big metalclad junction box and extend away from there to your new position.
Often this is done with huge kopex tubing to contain the new lengths of cable, but you could in theory use any means as long as you bear in mind safe zones etc.

-------------------------
----------------------------------------
Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 07 August 2014 01:51 PM
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mapj1

Posts: 2795
Joined: 22 July 2004

Would that be METAL conduit is not constrained Mike...............:-)

yes.
Metal conduit, not the toy plastic stuff. Sorry, my non-domestic side showing again, and not thinking of that.

-------------------------
regards Mike
 09 August 2014 09:05 AM
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Fm

Posts: 672
Joined: 24 August 2011

Earth clamp the conduits and loop and conductor back to the board.
Fit rubber grommett to the cut conduit and wire in t and e.
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