I was changing a damaged socket face in my lounge this weekend past. I had turned the downstairs ring main MCB off yet still had power to the socket. All the other sockets on the downstairs ring were off. I then turned the upstairs ring MCB off as well. This shut off power to the socket, so I thought that this individual downstairs socket had been wired as part of the upstairs ring. However when I turned the downstairs MCB back on , power returned to the socket. In essence this socket appears to be on both ring circuits, upstairs and down. There are only two cables coming in/going out of the socket. How can it be?
An electrical puzzle
- Thread starter icec111
- Start date
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Crossed ring mains, 1 leg of each in each MCB. End up having to isolate 2 circuits to work on either.
God knows what sort of fault would have to occur to trip the MCB`s, get it checked out, sooner rather than later.
God knows what sort of fault would have to occur to trip the MCB`s, get it checked out, sooner rather than later.
that wouldn't explain all the other sockets going off though.
this is really really strange. either the situation is not how he is describing it, he is using a flawed method for testing or there is something really strange going on (best i can think of is an automatic changeover switch somewhere but that seems kinda unlikely in a house).
this is really really strange. either the situation is not how he is describing it, he is using a flawed method for testing or there is something really strange going on (best i can think of is an automatic changeover switch somewhere but that seems kinda unlikely in a house).
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could be a socket downstairs spurred from upstairs ring. Have noticed this happen in kitchen installs during PIR's
B
breezer
baldelectrician said:
nope, not that either
B
Big_Spark
Get a "Martindale" or similar type of plugin socket tester, put it in the socket in question then turn off the ring main for downstairs.
It should go out, however her are a few reasons for there still seeming to be power at the socket.
1: Leakage on the cpc sufficient to illuminate a volt stick or god forbit your using a bloody neon driver!!
2: Some clown has shared a neutral bewteen the rings at some point due to damage for similar event.
3: Induced current from another cable (unlikely but no impossible)
I would suggest you attract the services of an electrician and get it sorted sooner rather than later if you are getting a reading from the socket when you use a plug-in tester.
Buy the tester first, B&Q sell them for about £15, it will soon let you know if there is a problem and whether you would be wise to call a spark or simply bin the original tester!!
It should go out, however her are a few reasons for there still seeming to be power at the socket.
1: Leakage on the cpc sufficient to illuminate a volt stick or god forbit your using a bloody neon driver!!
2: Some clown has shared a neutral bewteen the rings at some point due to damage for similar event.
3: Induced current from another cable (unlikely but no impossible)
I would suggest you attract the services of an electrician and get it sorted sooner rather than later if you are getting a reading from the socket when you use a plug-in tester.
Buy the tester first, B&Q sell them for about £15, it will soon let you know if there is a problem and whether you would be wise to call a spark or simply bin the original tester!!
Good point about the neon screwdriver (if that was what you were using).
It may give the impression power is on when it isn't. Various causes as mentioned.
If you were using a neon, 50p says you can't reproduce the problem by plugging a table lamp into the socket after you've put it all back together.
edited to add, and if you can, you've got a dangerous fault that needs professional rectification. Put my 50p towards the cost of a real electrician.
To be fair, I'd forgotten about neon screwdrivers, since I use a test probe to check presence of voltage.
It may give the impression power is on when it isn't. Various causes as mentioned.
If you were using a neon, 50p says you can't reproduce the problem by plugging a table lamp into the socket after you've put it all back together.
edited to add, and if you can, you've got a dangerous fault that needs professional rectification. Put my 50p towards the cost of a real electrician.
To be fair, I'd forgotten about neon screwdrivers, since I use a test probe to check presence of voltage.
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