Advice please - supply to shed disconnected after consumer unit upgrade

[Markcastle]

Hi all, I was hoping to ask a couple of questions and take advantage of your collective knowledge and recommendations.

If this is in the wrong forum please move.

I’ve recently moved into a new house, as part of the sale the vendor had the old fuse board replaced with a new consumer unit (CU). The work was carried out by an approved electrician and the vendor was issued with a certificate, on which it states that the supply to the shed (6 sockets and 1 light) has been disconnected due to fault readings and advising that further investigation is required in order to reinstate. Other than that the rest of the installation was fine.

The shed is supplied by a single cable (2.5mm2 by my estimates) running approx 10m underground in protected housing from the CU under the stairs, this terminates in a 2 way fuse box (MEM rewirable type, 5A for light and 15A for sockets) with main switch. This then feeds a single light and 6 sockets on a radial circuit. I checked the live supply before the fuse box in the shed and there is no current, I also checked the fuses and rewired the 5A one.

I then moved onto investigate the CU, it’s a British General one with 2 RCD’s and 10 MCB’s (6A, 16A, 32A and 40A). There are 6 MCB’s in use and labelled (shower, cooker, alarm, sockets, up lights and down lights), there is also one more MCB with a live wire attached but no label, the screw connecting it to the Busbar is also not tightened at all. What could this MCB be for?

I also found a single live and neutral pair (2.5mm2 estimated) taped together and pushed behind the other wires in the top of the CU. Could this be the disconnected supply to the shed? I haven’t been able to trace the supply back from the shed so I’m unsure. Would this be the way an electrician would leave a circuit that was disconnected from the CU? If these wires are the supply could I reconnect them in order to check for certain? If so how would you recommend I do this (use the 16A MCB etc)?

As the circuit displayed a fault I understand why it would have been disconnected, are there any tests that I can do myself that might identify the fault?

I hope that I’ve supplied enough info; I’d really appreciate any help you could offer.

Thanks

Mark

 

[Engineer54]

Seems like you're messing around inside a consumer unit, which can be dangerous. Why don't you just get a electrician in to check the garage circuit out properly, so it can either be be repaired and improved or as the case may be replaced!!

External electrical installations is definitely not in the realms of the DIY'er, so be warned!! Not only that, but this work could, if replacement is required, be notifiable along with a hefty 230 quid LABC inspection fee. Having a fully qualified electrician that is also Part P registered do the work, and that LABC fee disappears and you'll have peace of mind and a valid certificate of conformance to boot!!

 

[Octopus]

On the certificate for the new CU what does it "list" as the unlabelled circuit? What does it actually say about the "fault" on the shed circuit?

 

[Markcastle]

On the certificate for the new CU what does it "list" as the unlabelled circuit? What does it actually say about the "fault" on the shed circuit?

In answer to your questions -

There are 7 MCBs in use in the CU (live wires entering them)
Of these 6 are labelled
But on the certificate the are only 5 circuits listed (the shower circuit isn't mentioned)

So I'm not sure what that unlabelled MCB might be for, any ideas? Could it be the supply to the shed, left connected but not labelled?

In the 'comments on existing installation' section on the certificate it has this -

'satisfactory
Disconnected supply to shed due to fault readings. Further investigation req'd in order to reinstate'

The certificate doesn't seem much help in identifying a problem, I was told that the supply to the shed was working fine before the new CU was installed.

Ideally I'd like to identify the wires which feed the shed, then also try and help identify any fault with the installation in the shed, loose wires, water ingress etc with any checks I can do myself.

Thanks for your help

 

[Octopus]

In answer to your questions -

There are 7 MCBs in use in the CU (live wires entering them)
Of these 6 are labelled
But on the certificate the are only 5 circuits listed (the shower circuit isn't mentioned)

So I'm not sure what that unlabelled MCB might be for, any ideas? Could it be the supply to the shed, left connected but not labelled?

In the 'comments on existing installation' section on the certificate it has this -

'satisfactory
Disconnected supply to shed due to fault readings. Further investigation req'd in order to reinstate'

The certificate doesn't seem much help in identifying a problem, I was told that the supply to the shed was working fine before the new CU was installed.

Ideally I'd like to identify the wires which feed the shed, then also try and help identify any fault with the installation in the shed, loose wires, water ingress etc with any checks I can do myself.

Thanks for your help

re the labelling - poor workmanship I'm afraid. Re the unknown circuit - switch it off and see what doesn't work and re fault finding - good luck with this as you may need a MFT to check this out. What were the readings on the cert for the "shed" circuit?

 

[Markcastle]

re the labelling - poor workmanship I'm afraid. Re the unknown circuit - switch it off and see what doesn't work and re fault finding - good luck with this as you may need a MFT to check this out. What were the readings on the cert for the "shed" circuit?

Other than the short bit in the comments on existing installation part, I can see no other mention of the shed on the whole certificate. There are 5 circuits listed (sockets, up lights, Down lights, cooker, alarm) along with the test values next to each. However there is no mention of the shed circuit. Should there be?

Do you have any idea about what those taped together live and neutral wires in the CU might be?

Thanks

 

[Octopus]

How many RCD's does your CU have?

 

[Markcastle]

How many RCD's does your CU have?

It's a British General one with 2 RCDs and 10 MCBs. 6 are in use plus the one that isn't labelled.

 

[Octopus]

I really think that the person who fitted the CU was a bit of a cowboy. The "poor" circuit should have been tested and the results noted on the cert. The unlabelled circuit should also have been identified and tested. My guess is that the disconnected circuit is the shed circuit - and will trip the RCD.

I would recommend you get a competent spark in to test the circuits not on the certificate.

I feel sorry for people like you as you have a bit of a shambles on your hands.

Why don't you give a more accurate location and see if anyone on here is local to you?

 

[Markcastle]

Yea it looks that way. Thanks for all your advice.

Re that she'd circuit tripping the RCD, I guess there could be any number of reasons?

I live in Northwich, Cheshire. If anyone is local and would be able to help I'd really love to hear from them.

Thanks
Mark

 

[telectrix]

mark, if you still about, i have sent you pm. can sort it when i get back off holiday. 11th may.

 

[GMES]

mark, if you still about, i have sent you pm. can sort it when i get back off holiday. 11th may.

There you go Mark, Let Tel sort it for you, he Will be able to get to the bottom of it in no time.

 

[Markcastle]

Thanks very much for the offer tel

Mark

 

[Markcastle]

Quick update for anyone interested – Problem sorted

*

Over the weekend I went about some simple fault finding on the sockets, fuses etc. In one of the six double sockets (radial circuit) in the shed I discovered an unconnected neutral wire, which seemed strange as the screw connecting the other neutral was tight. I connected this back up and moved on. There are also two further sockets at the end of the garden (approx 40m away), they were IP55 but were in a bad state. The front weatherproof flaps had broken off at some point, I took the faceplate off and found it was full of wet soil, 2 worms and a slug! I disconnected the sockets, clipped the wires and taped them up. I then reconnected the supply in the consumer unit to a spare 16A MCB and tested the sockets in the shed, which were now working. So the waterlogged sockets at the end of the garden were the main problem, not such a big deal after all. I’ve now reconnected a new double IP55 socket and made sure it was fully sealed using silicone on the screws and around the supply entry hole. Tested it all again and all sockets are working perfectly, no problems at all.

*

Thanks for the advice and offer of help.

Mark

 

[Engineer54]

I doubt very much if you even possess the test equipment required to make the statement '' Tested it all again and all sockets are working perfectly, no problems at all.'' You're basically winging it on a hope and a prayer!!