Need Help

[tonywevans]

Hi,

I hope someone can help with this problem. I have been trying to locate and fix a fault in a domestic installation. All of the circuits were dead when I arrived. When I checked the fusebox none of the circuits were identified. When I removed the fuse for what should be the final ring the lights and cooker circuits were energised. When I checked the 30amp fuse for what should be the final ring I found 4 conductors wired in. I tested for end to end ring continuity for each combination of these conductors without success. The previous owner of the house was well known as an enthusiastic DIYer.

Would appreciate any advice on how I should proceed further.

 

[kung]

Hi Tony
Id say stop have a brew and start again dewire cu and do dead tests you might also find 2 radials instead of 1 ring hence no end-end readings start from first socket and discon outgoing feed and test back to board then add next socket feed and from that do same etc same with lights etc you say no power to circuits ? is main switch an rcd type and tripping or meter tails pulled and bad/loose conection etc etc ? or is it feed to cu ok and main switch faulty ? Id say you need a PIR when was the last one done ?

 

[tonywevans]

Hi Kung,

Many thanks for your advice. The fusebox is and old Wylex unit with re-wirable fuses and no RCDs at all anywhere in the installation. I'll let you know how I get on next week.

 

[kung]

Thanks and good luck Tony !
right pain when you have an installation wired weirdly i know its time consuming but when you have it sorted best to do a diagram of each circuit for record. With the no power fault was the main switch on and everything dead ?
Regards
Kung.

 

[tonywevans]

Yes. When I first arrived the main switch was on but there were no lights or cooker. I turned the power off at the main switch,removed the fuse for the sockets and then the lights and cooker came on when I turned the power back on at the main switch.

 

[kung]

Good luck Tony bit of an elimination fault find that one but strange on one of those cu's to latch up power to whole board ! from what your saying its on the socket circuit although if no end to end reading would be intresting to see how its wired ie one radial socket one feed for imm/boiler or 2 radials etc anythings possible lol even seen a porch light with no cpc off a junction on the ring under floor ! hang in there buddy all part of the fun. had a fault in kitchen ring on an old deaf doris's house all she kept doing was telling me she had to put her dinner on and what time would it be working ? told her it was gas ! repeated myself 16 times ! then whilst unplugging fridge etc under work surface all of a sudden heard a loud bang made my cheeks twitch a bit and banged me head on work top whilst i was scrambling out thought my back was getting hot she'd put the pan on and threw a handfull of wet mushrooms in the pan and i was getting splatterd with fat ! turned out to be faulty dishwasher was glad to get out of there !

 

[tonywevans]

Hi Kung,

I had a good laugh at your last posting.Thanks again for the help.

Well I de-wired the CU as you suggested and spent the rest of the day doing the dead tests on the sockets. Looks like 4 radials coming from the same fuse!

I found 3 faults in the sockets relating to a short between earth and neutral and a couple of sockets with conductors hanging out- one contacting with the metal back box.. I thought fixing these would do the trick so I rewired just the sockets into the CU and energised the circuit. This is where my nightmare begins. Each socket was showing live. When I plugged in a fan this appeared to work OK. So then I plugged in the freezer into the same socket and this was dead. So was the fridge.

I then de-wired the sockets in the CU and wired up the cooker and hob. Tests were OK. I then energised the cooker circuit and the timer light came on. I then switched the oven on and the timer light went out and the oven didn't get hot. I did the same thing with the hob with a similar result. I might have originally thought the oven itself was faulty but not the hob as well!

Somebody suggested I carry out Zs tests but I'm not sure this would be the right way.

I get the feeling I'm missing something a bit fundamental here so I would appreciate some more advice.

 

[Gravid]

Hey up Tony, did you check the fuses in the fridge/freezer, maybe they've blown.

 

[old dog]

hi sound like you are loosing power when you connect a load.
could be a loose connection on the main incomer.
check the terminals both sides of the main switch
is there a henley block present

 

[tonywevans]

Hi Old Dog,

That's what crossed my mind but I couldn't get my head round how this could happen.

Yes there is something like a Henley block on the neutral but there's a BS88 on the phase. This has a seal on it.

 

[old dog]

Hi Old Dog,

That's what crossed my mind but I couldn't get my head round how this could happen.

Yes there is something like a Henley block on the neutral but there's a BS88 on the phase. This has a seal on it.

yes just tighten up the connections on the main tails and check the terminations
supply and load side of the main switch in the cu
£5 its on the neutral

 

[tonywevans]

I checked and tightened the terminals on the incomer as suggested and I also replaced the switch on the CU. Unfortunately this hasn't fixed the problem. I still think there is a drop in power because I noticed the internal light in the fridge was on but the light was very dull.

The people in the house also mentioned that they have been experiencing mild shocks from the sink. On checking under the sink there looks as if the incoming water pipes were bonded at some point but there isn't a cable attached to the clamp. There's no main bonding at the CU.

 

[Spudnik]

What type of supply is it?

 

[tonywevans]

It's a PME.

Looked like we finally ran out of options so we contacted the DNO who checked out their side and advised that the cable in the street was corroded.

What test could I have done to detect the fault on the DNO side without having to eliminate problems in the installation first?

 

[Monkey1984]

If you checked the incoming voltage what was it showing out of interest? Say for example if you plugged an MFT into a socket and see what the voltage was registering at?

Only reason I ask is that you mentioned the fridge light was dull wondered if the incoming voltage was low?

 

[tonywevans]

The incoming voltage at the sockets was 230V.