Tripping ring main

[redkite58]

The problem I have is a ring main is tripping the whole house but nevertrios the rin. Main trip switch. I have by process of elimination identified the ring main that appears to have a fault. If turned off the rest of the electric works fine. Used a basic socket tester and all came back fine. Any suggestions would be really appreciated. I did manage to plug a lamp and test all sockets before it tripped. It didn't trip while doing that , tripped whole house again about 20 mins later. No high use items in fact only really used for bedside lamps Alexa and a diffuser or wife's hairdryer . Even trips with nothing connected and all affected sockets turned off

 

[Harry Bloomfield]

The problem I have is a ring main is tripping the whole house but nevertrios the rin. Main trip switch. I have by process of elimination identified the ring main that appears to have a fault. If turned off the rest of the electric works fine. Used a basic socket tester and all came back fine. Any suggestions would be really appreciated. I did manage to plug a lamp and test all sockets before it tripped. It didn't trip while doing that , tripped whole house again about 20 mins later. No high use items in fact only really used for bedside lamps Alexa and a diffuser or wife's hairdryer . Even trips with nothing connected and all affected sockets turned off

I think you need to identify, the actual device which is tripping, maybe with a photo? Likely, it will be an RCD, but we need to know..

 

[ericmark]

In the main, if it can trip with earth leakage, it has a test button. You can also get 30 mA, 100 mA, 300 mA and type S, AC, A, F, and B although unlikely to find latter 2. Seems likely an earth leakage trip, and one can have line - earth or neutral - earth, since the latter often does not go through an on/off switch, items must be unplugged, switching off and left plugged in does not help.

 

[redkite58]

Even trips with nothing in any of those sockets.

 

[opps]

When you say you unplugged everything, did you unplug things like the fridge/washing machine/boiler?

 

[Harry Bloomfield]

Even trips with nothing in any of those sockets.

You originally said....

The problem I have is a ring main is tripping the whole house but nevertrios the rin. Main trip switch.

But you still have not made it clear - what is tripping. As an alternative way to find out......

1. When that MCB, marked up as number 3 circuit is on, what actually trips? Might it be the one marked Main Switch, on the extreme right, which includes a button marked TEST? FYI, that is what is known as an RCD.

2. Does the above only trip, when that number 3 is turned on?

3. Does it trip instantly, after a delay, or when something is plugged into one of the sockets?

 

[redkite58]

It trips the main switch. When number 3 is on it trips the main switch even with nothing plugged into any of the sockets that is on the number 3 circuit.

 

[redkite58]

There is a delay before the main switch trips normally 5-20 minutes. All other electrics are fully operational

 

[ericmark]

There are three machines, the clamp-on ammeter, the RCD tester, and the insulation tester, they cost around £35, £70, and £35 and the latter which looks like this is the most likely to find the fault. However, you can get multi-faults building up to cause the trip, and faulty RCD's, but in the main if the RCD does not trip on ½ setting, we assume not a build up of faults, and since other circuits do not cause a trip, unlikely to be RCD at fault, so likely can be found with meter shown.

However, these meters use 250, 500, or 1000 volts DC, and are not really designed to be used by the untrained.

Sometimes we are lucky, we can remove a socket and find a dead spider or similar fault, but failing that it is a case of guessing approx centre of the ring final, and testing each half, then taking the faulty half and again guess approx centre and split into two quarters, and see which it is at fault, until the fault is found, the last one I did, someone had been a little careless with knife stripping cables, and the fixing screw was touching the neutral wire.

But there is no magic tester which can pinpoint the fault, we start with guess at likely cause, but if not lucky, it is down to slowly reducing the possibilities until the fault is found.

 

[chivers67]

So the RCD on the right actually trips out? Have you any areas where equipment could be wet?

Needs an insulation resistance test on the conductors with everything Unplugged and disconnected.

 

[Harry Bloomfield]

It trips the main switch. When number 3 is on it trips the main switch even with nothing plugged into any of the sockets that is on the number 3 circuit.

There is a delay before the main switch trips normally 5-20 minutes. All other electrics are fully operational

That suggests, that you have some current leakage, between the L and the E. Often that proves to be due to water, do you have any outdoor sockets or similar items on that ring circuit?

Were it a nail, screw or similarly damaged cable, then I would expect it to trip very quickly, but you mentioned a delay before it trips.

 

[pete01]

Check outside lights and sockets.

 

[opps]

It trips the main switch. When number 3 is on it trips the main switch even with nothing plugged into any of the sockets that is on the number 3 circuit.

I am not an electrician.

The thing that you call the main switch is the RCD. It monitors bridging between the earth and both the live and neutral. If that is tripping, you may have water somewhere in a device connected to the ring. It could be the boiler, it could be an exterior light fitting, it could be a fridge, and so on. Why not use an extension lead to power the devices that I suspect are still connected to the lower ring. Eg. if your fridge is on the ground floor ring, use the extension lead and power it from a socket upstairs. If the RCD doesn't trip after 24 hours, then use the extension lead to power the washing machine... keep going until you can eliminate each of the white goods.

But check things like exterior lights and exterior sockets (see if they run of the same 32 amp MCB), and isolate them as well, but eliminate one item at a time.

 

[ericmark]

it could be a fridge

A good point, although more likely the freezer, any device with a mineral insulated element can cause earth leakage if the seals are damaged, and freezers use mineral insulated elements for their auto defrost, however

Even trips with nothing in any of those sockets.

I would assume that includes freezer, and outside lights. And any FCU has been switched off, not just fuse removed.

Even trips with nothing connected and all affected sockets turned off

So yes question why 20 minutes before tripping, what has a 20 minutes delay?
.

 

[redkite58]

I do have an outdoor socket in a waterproof box / covering it's has a built in RCD . That is a deffo a good call to check more closely. I will take it apart tomorrow and check for any water leakage condensation thank you for that. Very rarely used so forgot about it. Thanks a lot .