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Discuss Consumer unit extension wiring in the UK Electrical Forum area at ElectriciansForums.net

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Hi all! I'm not a spark but know enough to be able to install off grid solar etc. I've just purchased a new house and have noticed the consumer unit was extended at some point:

[ElectriciansForums.net] Consumer unit extension wiring


The additional unit is from the kitchen as they had a new kitchen fitted. My concerns are with the quality of the work. No glands are used and all wiring enters the side, the cables also have sheathing cut short so the wires are exposed. I'd have thought some simple chaffing could expose a wire and short the consumer unit:


[ElectriciansForums.net] Consumer unit extension wiring


Due to these concerns I opened up the box to take a look at the method used to extend the wires:

[ElectriciansForums.net] Consumer unit extension wiring


I have a few questions here... why are glands not used? Is it ok not to use a DIN rail and simply extend all circuits with lever terminals? If so, would splice connectors 221-2411 not be more suitable? If the cables aren't long enough to reach a DIN rail, would it be best to use a Wiska Consumer Unit Relocator for any circuits that do have a wire long enough, and then extend the others?

I'm assuming this is legal, but sloppy work.
 
It's rough but, provided connectors are able to handle the rated current of each outgoing circuit, there's no real issue on that front.

Cables should indeed be restrained and IP rating of enclosures maintained. The main issue, as you've highlighted, is cable sheaths and exposed insulation entering through a cut metal edge. There are a number of ways this could be resolved and glanding individual cables is one of them. To make the best of what you have, I'd probably replace the 2 gang surface box with a small adaptable box and run a short length of 2x2" PVC trunking between it and the board, which would provide space to place some sort of gromment over that cable entry.

I'd be slightly concerned about what's inside your CU, but it may all be fine.
 
Cut that box the get the cables out without dissing the wagos. Replace with a Wago XL box, which has cable restraint built in. Then tidy up the connections 1 at a time. Be nice to see a pic. of the CU wiring.
 
Cheers all, I like the idea of a Wago XL box - I'll have to check if the original cables are long enough to reach a box as they seem to be quite short.

Here's the CU:

[ElectriciansForums.net] Consumer unit extension wiring

[ElectriciansForums.net] Consumer unit extension wiring



Seems ok although not the neatest and the grommet looks cross threaded:

[ElectriciansForums.net] Consumer unit extension wiring


What was slightly alarming was the lack of sheathing on an earth cable in the side entry:

[ElectriciansForums.net] Consumer unit extension wiring



I've put a sheathing on it for now as a temporary measure until its sorted properly. As I unscrewed it, it was pretty chewed up where it joined the earth bar also:

[ElectriciansForums.net] Consumer unit extension wiring


I'll look into replacing the surface box based upon how long the cables are...
 

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I hate to say it, but looking at that chewed up earth, I fear every terminal was tightened with an impact driver. At an absolute minimum I'd turn the power off and look at the other CPC's (earth wires). If required trim them so you are biting on undamaged copper and loop the end around (similar to how the Neutral's are) so you get a better connection.
 
You would normally put the two lighting circuits on separate RCDs, so one RCD tripping doesn't plunge the whole house into darkness. But it could be done this way because of a borrowed neutral e.g. the landing light (L supplied from downstairs, N to upstairs) and they couldn't be bothered to fix that.
 
You would normally put the two lighting circuits on separate RCDs, so one RCD tripping doesn't plunge the whole house into darkness. But it could be done this way because of a borrowed neutral e.g. the landing light (L supplied from downstairs, N to upstairs) and they couldn't be bothered to fix that.
A borrowed neutral is required to be on one circuit rather than just one RCD though for safety reasons (which of course would no longer render it a borrowed neutral).
 
Pretty grim. I've spent time on it today to put new cables in and glands:

[ElectriciansForums.net] Consumer unit extension wiring



Still not perfect but have addressed the side entry issues. Unfortunately the cables aren't long enough to allow the Wago junction box to be used correctly, what's the best way to resolve this, if any?


[ElectriciansForums.net] Consumer unit extension wiring
 

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