House ring main failed - help!

[Richard10002]

Watching TV this evening when everything went off, or so it seemed. However, when I got to the main fuse box, if I turned off the “downstairs ring main”, the “main switch” that was automatically turning everything off, stayed on.

 

So the problem is somewhere in the downstairs ring main sockets. I turned all the sockets I could find/think of off at their switches, thinking this would remove the problem, then I could turn them on one by one, and the faulty one would cause the switch to throw.

 

Not to be - having turned all the sockets off at the socket switch, turning the downstairs ring main switch on caused the main switch to throw. So I either haven’t found all of the sockets on the ring, or the problem is with the wiring to the sockets, or something else that I can’t think of.

 

I don’t want to waste the time waiting for an electrician if this is something I can diagnose myself, so I wonder if anyone, (an electrician?), has any pointers. I’ve got a few tools and meters, so should be able to do what an electrician would do.... up to a point.

 

Hope that makes sense,

 

Richard

 

BTW: it seems that we have a Kitchen and Garage ring main, so there are some ground floor sockets that work, and I have managed to get critical stuff working with a few extension leads, (TV and Fridge Freezer mainly).

 

 

[TheBiscuits]

 

Start by unplugging everything from the ring and see if it will come back on.  A faulty appliance can cause this, and is obviously easier to fix than a circuit fault!

 

Have you missed any fused spurs that aren't sockets when switching stuff off?  Boiler, immersion heater, towel rail, underfloor heating etc.

 

Is anything wet? Apparently it's been raining a bit today ...

 

Did you get a flicker of lights just before it went off? There may well have been strange power surges because of flooding in the areas nearby.

 

I am assuming that what you are calling the main switch is actually an RCD (it'll have a test button on it) for all the above, but you'll do no harm by checking all of them if not.

 

 

 

 

 

 

 

 

[hovrin]

I'm not an electrician (though I have rewired two houses) but it sounds to me like an earth fault. As TheBiscuits says, unplug everything first. Then if the problem remains, with the isolator switch off, check for continuity from live and neutral to earth. If that exists then you will have to work through your sockets one by one, removing the covers and checking the connections.

[Tony Brooks]

Sounds to me as if the "main switch" is an RCD so that suggests there is a neutral to earth leak somewhere.  Do as @TheBiscuits says, especially any spurs. There may be such things in the kitchen for under counter appliances. If the house is older and extended then sompoen might have spured extension lighting off the ring main.

 

Look for signs of damp/water near the sockets and spurs.

 

Then it depends upon how competent you are with mains work. I would carefully take each socket off the wall for inspection of the connections. Look for things like cables that have been trapped so insulation has rubbed through - probably black/blue ones but check all. Normally there will be just two cables to each socket. If you find three then you have found a spur so find out where it goes.

 

If that does not find a fault or if you are in any way concerned about doing  get a professional in. Mains cam kill.

[Alan de Enfield]

6 hours ago, Richard10002 said:

So the problem is somewhere in the downstairs ring main sockets. I turned all the sockets I could find/think of off at their switches, thinking this would remove the problem, then I could turn them on one by one, and the faulty one would cause the switch to throw.

 

 

Turning off switches at the socket doesn't stop the 'leccy getting to them, if theere is a fault in the wiring in the switch, (or, as we had once a mouse in the wall chewing the wires), switching off switches doesn't isolate them.

 

As the Biscuits suggests, unless you have test equipment, all you can do is disconnect everything from the sockets and see if it then works OK.

Alternatively, in your 'fuse box' there may be different circuits, if so, swith off each circuit breaker individually, put the ;master back on, and then turn on the individual circuit breakers one by one until you identify the faulty one, you can then disconnect sockets and 'fault-find' it.

[robtheplod]

Do you have anything external that gets it's power from the ring main? with it being so wet it has to be up there on suspects.... good luck!!

[frangar]

21 minutes ago, Alan de Enfield said:

 

 

Turning off switches at the socket doesn't stop the 'leccy getting to them, if theere is a fault in the wiring in the switch, (or, as we had once a mouse in the wall chewing the wires), switching off switches doesn't isolate them.

 

As the Biscuits suggests, unless you have test equipment, all you can do is disconnect everything from the sockets and see if it then works OK.

Alternatively, in your 'fuse box' there may be different circuits, if so, swith off each circuit breaker individually, put the ;master back on, and then turn on the individual circuit breakers one by one until you identify the faulty one, you can then disconnect sockets and 'fault-find' it.

The breakers are usually single pole & on the live side tho....whilst it’s a good start it won’t find a neutral/earth fault. 
 

This sort of fault is why rcbo’s are better than one overall RCD. 

[twbm]

Proably worth taking the fronts off all the sockets. I had this, admittedly in the garden shed,  - a particularly fat slug had managed to bridge the live and earth on it's travels.  Also it's not unheard of for wires to work loose, I've no idea how.   

[Jen-in-Wellies]

8 minutes ago, twbm said:

Proably worth taking the fronts off all the sockets. I had this, admittedly in the garden shed,  - a particularly fat slug had managed to bridge the live and earth on it's travels.  Also it's not unheard of for wires to work loose, I've no idea how.   

You managed to still tell it was a slug afterwards!

[Guest]

15 minutes ago, twbm said:

 Also it's not unheard of for wires to work loose, I've no idea how.   

 

They can. About ten years after moving into this house we started to get a 'fishy' smell in the lounge whenever we used the kettle in the kitchen. This turns out to be an indication of over heating electrical insulation.

 

On pulling each socket plate off I found one where the screws were so loose that I could pull the wires out without further loosening. There was also evidence of over heating so I renewed the whole fitting. Never been an issue since.

 

When we had a new kitchen fitted 3 years ago the sparky found similar at the main trip switch in the fuse box, that was also replaced due to heat damage.

 

[Guest]

6 hours ago, TheBiscuits said:

 

Start by unplugging everything from the ring and see if it will come back on.  A faulty appliance can cause this, and is obviously easier to fix than a circuit fault!

 

Have you missed any fused spurs that aren't sockets when switching stuff off?  Boiler, immersion heater, towel rail, underfloor heating etc.

 

Is anything wet? Apparently it's been raining a bit today ...

 

Did you get a flicker of lights just before it went off? There may well have been strange power surges because of flooding in the areas nearby.

 

I am assuming that what you are calling the main switch is actually an RCD (it'll have a test button on it) for all the above, but you'll do no harm by checking all of them if not.

 

 

 

 

 

 

 

 

 

Anything with an element in them would be a prime suspect, towel rail, immersion heater etc etc. but shouldnt an immersion heater be on its own dedicated circuit/circuit breaker?

[Tracy D'arth]

5 minutes ago, The Happy Nomad said:

 

They can. About ten years after moving into this house we started to get a 'fishy' smell in the lounge whenever we used the kettle in the kitchen. This turns out to be an indication of over heating electrical insulation.

 

On pulling each socket plate off I found one where the screws were so loose that I could pull the wires out without further loosening. There was also evidence of over heating so I renewed the whole fitting. Never been an issue since.

 

When we had a new kitchen fitted 3 years ago the sparky found similar at the main trip switch in the fuse box, that was also replaced due to heat damage.

 

I have noticed that fishy smell, its always an accessory that is burning, cables don't smell the same.

[Guest]

Just now, Tracy D'arth said:

I have noticed that fishy smell, its always an accessory that is burning, cables don't smell the same.

 

Well all l can say is a rellie who is a sparky told me what to look for and the work I did cured it.

[Tracy D'arth]

1 minute ago, The Happy Nomad said:

 

Well all l can say is a rellie who is a sparky told me what to look for and the work I did cured it.

Yes, its the plastic that sockets etc. are made from. The loose wire means that the terminal moulded into the plastic gets hot and smells.  

[Guest]

1 minute ago, Tracy D'arth said:

Yes, its the plastic that sockets etc. are made from. The loose wire means that the terminal moulded into the plastic gets hot and smells.  

 

I may have 'misremembred' the exact precise bit of the system that smells like fish when it over heats but the fact is the screws were loose and once the socket was replaced and the screws correctly tightened I cured it. Ok?

[Rob-M]

12 minutes ago, Tracy D'arth said:

Yes, its the plastic that sockets etc. are made from. The loose wire means that the terminal moulded into the plastic gets hot and smells.  

According to Google...

The electrical components and wires in your walls and outlets are coated with heat resistant chemicals and plastic coating for insulation. When these chemicals and plastic heat up significantly, they give off a burning odor that can smell like fish.

[Wizzer]

If it is an RCD that is tripping unplug the fridge and  try it again. 

[matty40s]

.....critical......TV......??

[Guest]

1 hour ago, Rob-M said:

According to Google...

The electrical components and wires in your walls and outlets are coated with heat resistant chemicals and plastic coating for insulation. When these chemicals and plastic heat up significantly, they give off a burning odor that can smell like fish.

 

That is exactly what I remember I was told, but it was a long time ago so I could have been mistaken (but clearly I wasn't).

 

What I couldn't work out at first was the association between using the kettle in the kitchen and the smell appearing in the lounge, but of course that dodgy connection was the weak link in the ring main.

[JonesBoy]

As has already been said the main switch on fuse board will be a RCD so you have an earth leakage fault, again make sure everything on that ring main is unplugged and any items on switched spurs are disconnected. Then try again.

If success then plug items back in one by one until you find the faulty item.

If RCD still trips after all unplugged then you have a wiring problem and these can be very hard to find. Follow Tony Brooks advice and if no luck like he says get an electrician in.

Could be all sorts, mice love wires, nails in floors walls that have nicked a wire and then insulation broken down over time, needs a megger tester on the job.

Sorry to say not easy. But hope all goes well.

[Tony Brooks]

regulations or no regulations if I could not find the fault as we have detailed I would get my megger out and start testing cables between outlets but if I posses a megger it follows I must have experience of using it. I don't think its wise to advise the OP how to do that because I suspect its against the "cowboy tradesman protection" regulations.

[Richard10002]

Thanks to all for the advice and info!
 

I’m “capable” with mains, having done a lot on the boat over the years, and bits at home, so should be OK opening up the sockets and checking the connections.

 

The “main” switch I refer to IS an RCD which controls several circuits.

I have narrowed it down to the Downstairs Ring circuit

 

I think I’ve found everything on the circuit and have unplugged everything from the sockets on the circuit. It’s obviously possible I may have missed a socket or spur, but I don’t think so.

 

Unfortunately my meters are on the boat which is not accessible during the current floods in Manchester..... so it looks like I’ll be taking the socket covers off, one by one  

Thanks again... I’ll report back at some point.

[Tony Brooks]

The meter you have on the boat is unlikely to help much here.

 

Its probably a neutral to earth fault because if its line to earth the MCB would probably trip.

 

You need a much higher voltage to "stress" the insulation than a multimeter can provide. From memory I would use the Megger 500 volt range at home.

[system 4-50]

There will be 2 live wires and 2 neutral wires for the ring main going into the MCB in the consumer unit. 

I would disconnect 1 live AND its associated  neutral and insulate the ends. Then I would open a socket half way around the ring and separate the two sets of wires and insulate all of them. You have now divided the ring main into 2 legs, one of which is connected to the cu. Safely energise at the CU. If the RCD does not trip then then the leg you have energised is ok and the fault is on the other leg.  Stick a lamp into various sockets to see which sockets are on the energised leg. Repeat the process with the other leg.  When you have identified the failing leg, then halve it and repeat the process.  Eventually you should be able to determine which is the failing length of cable. Examine for for faults in either the live or the neutral line.  This should work without many more tools than a screwdriver or 6.  Anybody want quible with the method?  (Don't overload the ringmain when divided.)

[Tony Brooks]

6 minutes ago, system 4-50 said:

There will be 2 live wires and 2 neutral wires for the ring main going into the MCB in the consumer unit. 

I would disconnect 1 live AND its associated  neutral and insulate the ends. Then I would open a socket half way around the ring and separate the two sets of wires and insulate all of them. You have now divided the ring main into 2 legs, one of which is connected to the cu. Safely energise at the CU. If the RCD does not trip then then the leg you have energised is ok and the fault is on the other leg.  Stick a lamp into various sockets to see which sockets are on the energised leg. Repeat the process with the other leg.  When you have identified the failing leg, then halve it and repeat the process.  Eventually you should be able to determine which is the failing length of cable. Examine for for faults in either the live or the neutral line.  This should work without many more tools than a screwdriver or 6.  Anybody want quible with the method?  (Don't overload the ringmain when divided.)

 

NO, its what I would do but use a megger on each leg as I have one  rather than energise it. I think there is a good chance it will turn out to be behind a socket. However is a householder allowed to play with the conections in a consumer unit. I rather suspect not.

Edited January 21, 2021 by Tony Brooks