Electric keeps tripping - possibly found source

FFHillbilly

silvercar said:

Small update. Guy came, but he is only the “make safe” team so just looked and booked it in for for “test and trace” to come tomorrow.

as it happens, from 4pm it’s been behaving albeit with only a few items plugged back in. His throw away comment was that electric car chargers can sometimes cause other circuit breakers to flip, so even though the charger has its own flippy switch, it could cause the others to go. 

do you have an electric car chargepoint? which circuit on the consumer unit is it connected to?

from the picture you posted it looked like the RCD had tripped as well as the MCB for the socket circuit, yet I can't seem to see that anywhere in writing in the comments afterwards, just a lot of " the flippy switch has gone, the main circuit, the dodgy one" etc which is not very clear

silvercar

FFHillbilly said:

silvercar said:

Small update. Guy came, but he is only the “make safe” team so just looked and booked it in for for “test and trace” to come tomorrow.

as it happens, from 4pm it’s been behaving albeit with only a few items plugged back in. His throw away comment was that electric car chargers can sometimes cause other circuit breakers to flip, so even though the charger has its own flippy switch, it could cause the others to go. 

do you have an electric car chargepoint? which circuit on the consumer unit is it connected to?

from the picture you posted it looked like the RCD had tripped as well as the MCB for the socket circuit, yet I can't seem to see that anywhere in writing in the comments afterwards, just a lot of " the flippy switch has gone, the main circuit, the dodgy one" etc which is not very clear

Yes we have one. Don’t know which circuit it is on, but not the one causing the problem. It was fitted months ago and hasn’t previously caused any problem. 

As in the picture, the MCB flips and the RCD goes half way down at the same time. Does that make a difference?

FFHillbilly

silvercar said:

FFHillbilly said:

silvercar said:

Small update. Guy came, but he is only the “make safe” team so just looked and booked it in for for “test and trace” to come tomorrow.

as it happens, from 4pm it’s been behaving albeit with only a few items plugged back in. His throw away comment was that electric car chargers can sometimes cause other circuit breakers to flip, so even though the charger has its own flippy switch, it could cause the others to go. 

do you have an electric car chargepoint? which circuit on the consumer unit is it connected to?

from the picture you posted it looked like the RCD had tripped as well as the MCB for the socket circuit, yet I can't seem to see that anywhere in writing in the comments afterwards, just a lot of " the flippy switch has gone, the main circuit, the dodgy one" etc which is not very clear

Yes we have one. Don’t know which circuit it is on, but not the one causing the problem. It was fitted months ago and hasn’t previously caused any problem. 

As in the picture, the MCB flips and the RCD goes half way down at the same time. Does that make a difference?

to clarify, both the MCB and the RCD are operating. the fact that the RCD goes halfway down is just a feature to let you know it's tripped due to an earth fault rather than someone manually turning it off. 
so it's likely a low resistance fault between live and earth thats causing it, unlikely to be an appliance(connected via plug of fused spur) as they all have 13A fuses and this fault is causing a 20A MCB to operate repeatedly. likely to be a fault in the fixed wiring, damaged insulation, screw or nail penetration, water in a joint box etc I'm sure your test and trace team will find it tomorrow

the car charger you have would appear to have be fitted incorrectly, if it is on one of the unmarked MCB's on the right side of the consumer unit, fed downstream of a Type AC RCD

silvercar

FFHillbilly said:

silvercar said:

FFHillbilly said:

silvercar said:

Small update. Guy came, but he is only the “make safe” team so just looked and booked it in for for “test and trace” to come tomorrow.

as it happens, from 4pm it’s been behaving albeit with only a few items plugged back in. His throw away comment was that electric car chargers can sometimes cause other circuit breakers to flip, so even though the charger has its own flippy switch, it could cause the others to go. 

do you have an electric car chargepoint? which circuit on the consumer unit is it connected to?

from the picture you posted it looked like the RCD had tripped as well as the MCB for the socket circuit, yet I can't seem to see that anywhere in writing in the comments afterwards, just a lot of " the flippy switch has gone, the main circuit, the dodgy one" etc which is not very clear

Yes we have one. Don’t know which circuit it is on, but not the one causing the problem. It was fitted months ago and hasn’t previously caused any problem. 

As in the picture, the MCB flips and the RCD goes half way down at the same time. Does that make a difference?

to clarify, both the MCB and the RCD are operating. the fact that the RCD goes halfway down is just a feature to let you know it's tripped due to an earth fault rather than someone manually turning it off. 
so it's likely a low resistance fault between live and earth thats causing it, unlikely to be an appliance(connected via plug of fused spur) as they all have 13A fuses and this fault is causing a 20A MCB to operate repeatedly. likely to be a fault in the fixed wiring, damaged insulation, screw or nail penetration, water in a joint box etc I'm sure your test and trace team will find it tomorrow

the car charger you have would appear to have be fitted incorrectly, if it is on one of the unmarked MCB's on the right side of the consumer unit, fed downstream of a Type AC RCD

Thank you. The weather seems to suggest it is damp getting in somewhere, particularly as it’s been working ok for the last 12 hours and it’s been dry. It could have dried out.

Of all the electrics in the house, I would have expected the car charger to be fitted correctly. It has its own box isolation unit out of picture. Done by one of the leading suppliers and we have all the paperwork for it. Also the charger has a built in PEN (?) protector and has been working through, even when this circuit was off.

silvercar

The electrics policy with my account only covers emergencies, so they won’t now cover trace. I have a local guy coming later today.

In the meantime, I may have found a damp spot - would you think this could be a problem:

Section62

silvercar said:

In the meantime, I may have found a damp spot - would you think this could be a problem:

Possibly, but your electrician is going to need to take a methodical approach to tracing the fault(s) to ensure everything is fixed, rather than having a guess and change something in the hope that might work.  I.e. if they just replace the 20A MCB they aren't really doing their job properly.

It is also worth noting that the 20A MCB is designed to break at a current level in excess of 20A.  The RCD is designed to break with a current imbalance of less than 30mA.  I think it would be unusual if a 'live' to 'earth' leakage through (say) a damp wall were able to repeatedly cause both the RCD and MCB to break, but then be resettable and stay on for some period of time.

silvercar

Section62 said:

silvercar said:

In the meantime, I may have found a damp spot - would you think this could be a problem:

Possibly, but your electrician is going to need to take a methodical approach to tracing the fault(s) to ensure everything is fixed, rather than having a guess and change something in the hope that might work.  I.e. if they just replace the 20A MCB they aren't really doing their job properly.

It is also worth noting that the 20A MCB is designed to break at a current level in excess of 20A.  The RCD is designed to break with a current imbalance of less than 30mA.  I think it would be unusual if a 'live' to 'earth' leakage through (say) a damp wall were able to repeatedly cause both the RCD and MCB to break, but then be resettable and stay on for some period of time.

I thought one tripping was causing the other one to go at the same time. And I thought the bigger one only went because the thinner one tripped. 

diystarter7

silvercar said:

Small update. Guy came, but he is only the “make safe” team so just looked and booked it in for for “test and trace” to come tomorrow.

as it happens, from 4pm it’s been behaving albeit with only a few items plugged back in. His throw away comment was that electric car chargers can sometimes cause other circuit breakers to flip, so even though the charger has its own flippy switch, it could cause the others to go. 

Hi OP
Thanks for the update.
That must have cost you a bit of money and then more money. Did they make you aware of that?
I'm sure you did but I always try to get a good idea of a price and scenarios.
Good luck

diystarter7

silvercar said:

The electrics policy with my account only covers emergencies, so they won’t now cover trace. I have a local guy coming later today.

In the meantime, I may have found a damp spot - would you think this could be a problem:

Just read this
Great stuff 
Good luck
ps - is that damp?

Ben1989

TL;DR

We had a circuit that kept going. Could not figure it out at all. Unplugged everything in the house.

Turned out we had damp (and still have) in our gable wall and had rusted the upstairs light feed conduit and caused the wire to degrade. The only reason I knew this however was because I hammered the plaster off a small section of the wall. Electrician ended up isolating the wire and putting all lights on one circuit with the feed wire coming through internal walls.