Checking sockets - where to start?

[pippinontheroo]

Hi.

My RCD tripped yesterday evening. I identified that the problem is on the Ring Main (Everything unplugged). When ring main set to on the RCD is triggered.

Left all other circuits on over night with no problems.

I've got up this morning and just switched the ring main on. No trip. (Nothing plugged in still).

I tried switching the ring main on numerous times yesterday with nothing plugged in and it tripped every time. This morning no tripping with same conditions.

What's my next move? Tempted to try the Hoover in every socket to see if any particular socket is tripping - Is their any better order to do this?

Any suggestions appreciated. Cheers.

 

[SJD]

if it is a N to E short somewhere, then the tripping (or not) can depend on loading on other circuits connected to the same RCD.

For example, was there lighting in use last night (on this RCD) that is now switched off?

Ideally, you need someone with test equipment to look for this kind of fault.

 

[Spoon]

Hi and welcome to the forum mate.
Without proper testing equipment it's going to be hit and miss.
The fault could be a number of things.
If you wanted to try and find the fault yourself then one of the things you could do is take the sockets off and visually check to see if there is anything obvious that could be causing the trip.

 

[MJPD29]

Unplug everything and see if it will reset. Failing that start with googling local electricians id say as if it is a wiring fault you'll find it hard to find without test gear. Is there anything connected off the ring also, possibly an outside light out the back of a socket for example.

 

[pippinontheroo]

if it is a N to E short somewhere, then the tripping (or not) can depend on loading on other circuits connected to the same RCD.

For example, was there lighting in use last night (on this RCD) that is now switched off?

Ideally, you need someone with test equipment to look for this kind of fault.

Ah ok. That's interesting as it seems to have happened when my daughter was using the shower which is on a separate circuit connected to the RCD. I'd ruled it out for that reason.

There were no lights on at the time, but there were during testing and not this morning. The lights are separate from the other circuits in that they can be on when the other circuits have triggered the rcd.

So given it was the ring main triggering the RCD then the fault will be on that BUT it may only trigger if the total load on ALL circuits reaches a certain level?

My daughter had just switched off a hair dryer when it happened.

Apologies for my ignorance and really appreciate your reply.

 

[pippinontheroo]

Ah ok. That's interesting as it seems to have happened when my daughter was using the shower which is on a separate circuit connected to the RCD. I'd ruled it out for that reason.

There were no lights on at the time, but there were during testing and not this morning. The lights are separate from the other circuits in that they can be on when the other circuits have triggered the rcd.

So given it was the ring main triggering the RCD then the fault will be on that BUT it may only trigger if the total load on ALL circuits reaches a certain level?

My daughter had just switched off a hair dryer when it happened.

Apologies for my ignorance and really appreciate your reply.

Ha... Left the first paragraph in by mistake... shower took place earlier... she was NOT using a hair dryer while taking a shower

 

[pippinontheroo]

Unplug everything and see if it will reset. Failing that start with googling local electricians id say as if it is a wiring fault you'll find it hard to find without test gear. Is there anything connected off the ring also, possibly an outside light out the back of a socket for example.

Thanks for the reply. Did all that last night. It refused to reset last night. Got up this morning (Everything the same) but it DID reset.

Sounds like a problem when the overall load is quite high.

 

[pippinontheroo]

Hi and welcome to the forum mate.
Without proper testing equipment it's going to be hit and miss.
The fault could be a number of things.
If you wanted to try and find the fault yourself then one of the things you could do is take the sockets off and visually check to see if there is anything obvious that could be causing the trip.

Thanks for that. My daughter had just used a hairdryer (claims the power went off after she had stopped using it though). Is there any logic in starting with the plug she was using?

 

[Deleted account]

As sjd said it may not be the socket circuit that has the fault. I know that sounds weird considering it doesn’t trip when that circuit is off, but based on the information you’ve given it may be the case.

If it’s an earth neutral fault somewhere it may need a high load to trigger it. A high load from the ring but other circuit on the rcd may be smaller loads like lighting or boiler etc... will not trigger fault.

When you switch off the breaker you are only isolating the live conductor. The earths are still all connected together in the fuse board and the neutrals are all still connected in the fuse board.

This is how a fault can trigger rcd to trip even if the faulty circuit is turned off.

This is one instant you need test gear and someone compitant to use it to find issue.

 

[pippinontheroo]

As sjd said it may not be the socket circuit that has the fault. I know that sounds weird considering it doesn’t trip when that circuit is off, but based on the information you’ve given it may be the case.

If it’s an earth neutral fault somewhere it may need a high load to trigger it. A high load from the ring but other circuit on the rcd may be smaller loads like lighting or boiler etc... will not trigger fault.

When you switch off the breaker you are only isolating the live conductor. The earths are still all connected together in the fuse board and the neutrals are all still connected in the fuse board.

This is how a fault can trigger rcd to trip even if the faulty circuit is turned off.

This is one instant you need test gear and someone compitant to use it to find issue.

Thanks for that. I'll call a professional!