- Reaction score
- 5,636
I rather foolishly booked in a fault finding job in a 2 hour slot thinking I could solve it quickly, I couldn't!
It has me confused, although I haven't let myself slow down yet and focus so you guys may point out something obvious.
It is an intermittent tripping MCB on a 32A ring ciruit (sometimes the RCD trips) on a dual RCD board. It trips a number of times each day. This has been going on for perhaps a week. Over the last 2 days 5 sockets have actually stopped working completely even with the power on. The ring feeds the whole house.
r1 = 0.14 Mohm (140,000 ohms)
r2 = 28K ohms (28,000 ohms)
rn = 0.7 ohms
With all sockets connected and the ring split in the CU I get :
Leg 1 = L/N - E 0.01Mohms
Leg 2 = I didn't write down the results but they were >1Mohm.
When I split the ring at one socket the IR results were all >1Mohm when tested in the CU, I didn't test at the split socket.
I think I'm getting confused because of the 5 non working sockets. If a ring is broken (as this is) all sockets should still work. Am I right in thinking there HAS to be 2 faults either side of those non working sockets (assuming they are not all spurred from the same socket) or am I missing something?
Usually, in order to find the break I would split the ring. Reconnect the leg that has continuity with the relevant leg in the CU liven them up and eliminate the working ones, but if there are 2 breaks this wont work, i don't think!
Update... the customer has literally just rang saying he removed a socket and just plastered in the cables a while ago and when he bangs that part of the wall it trips! However, this would be just one fault and would still not stop 5 sockets from working!!
It has me confused, although I haven't let myself slow down yet and focus so you guys may point out something obvious.
It is an intermittent tripping MCB on a 32A ring ciruit (sometimes the RCD trips) on a dual RCD board. It trips a number of times each day. This has been going on for perhaps a week. Over the last 2 days 5 sockets have actually stopped working completely even with the power on. The ring feeds the whole house.
r1 = 0.14 Mohm (140,000 ohms)
r2 = 28K ohms (28,000 ohms)
rn = 0.7 ohms
With all sockets connected and the ring split in the CU I get :
Leg 1 = L/N - E 0.01Mohms
Leg 2 = I didn't write down the results but they were >1Mohm.
When I split the ring at one socket the IR results were all >1Mohm when tested in the CU, I didn't test at the split socket.
I think I'm getting confused because of the 5 non working sockets. If a ring is broken (as this is) all sockets should still work. Am I right in thinking there HAS to be 2 faults either side of those non working sockets (assuming they are not all spurred from the same socket) or am I missing something?
Usually, in order to find the break I would split the ring. Reconnect the leg that has continuity with the relevant leg in the CU liven them up and eliminate the working ones, but if there are 2 breaks this wont work, i don't think!
Update... the customer has literally just rang saying he removed a socket and just plastered in the cables a while ago and when he bangs that part of the wall it trips! However, this would be just one fault and would still not stop 5 sockets from working!!
Last edited:
