Engineer Lane said:
When built 14 years previously, one of the the boiler mounting rails screws was drilled through the negative conductor - opening the ring.
There's no negative in AC wiring. I know you mean the neutral, but you should use the correct terms, or you might confuse people who don't know much.
the black wire had not been connected, leaving the ring open as a large spur.
No - not a large spur. If both conductors had been broken you'd have had two radials - not sure what the term is for what you had.
Get yourself a ring tester and check that the ring is actualy a ring!
What is a "ring tester", and how does it work?
From what you have said, the culprit is defo the kitchen ring.
Somewhat of a leap to say it is
definitely a problem with the kitchen ring - you don't even know that there is a separate circuit for the kitchen, or if there is, whether it's a ring or a radial. Also Jonifresh's computer is in the corner of the living room right under the consumer unit. Maybe there's absolutely nothing wrong with the wiring, it's just too close.
The tester will confirm if the ring is open.
How will it do that?
But I dont think it will show where the "break is". After confirming it's open, you will need to look into every socket/fcu to check that both sides of the ring are connected. If these are all ok - a power off job.
You would also need to check at the CU to check at both ends of the ring are terminated correctly. One for the pro's this, unless you are very competant.
IF you're right about the break in the ring cable, then sooner or later you have to deal with the fact that the break may be in the cable between the CU and the first accessories on the ring. If you don't think that someone should disconnect or even inspect the connections at the CU, then you're suggesting an awful lot of work which might not yield any results.
If all of the above is in order, the continuity will need to be checked out socket/fcu to socket/fcu (in case someone has fixed a kitchen cabinet to the wall and drilled through the wiring!) in turn. A quick visual check of the locations of all wall hung items (ie are the mounting screws directly in line above/below sockets/fcu's) could be done in minutes.
And what if they look like they might be? The only way to find out would be to start diving into the middle of the circuit, which is not what the first step should be. This is not a very "engineer-like" approach to problem solving!
The continuity checking can start between a socket/fcu and one, say, 3 steps along the circuit. Then, if you find a problem in any group of sockets/fcu's, you can break them down further.
To check the continuity, both sides of the ring in each socket/fcu should be removed from that socket and its neighbour, and ring the wiring out between them.
That's a ludicrous way to check the continuity of a ring.
If you are not that competant with a multimeter, then get the spart to do this for you. Neware that it could be time consuming, but I doubt the parts bill will be much!
Actually it won't be time consuming, as that's not the way that anybody would check it.
This is what you do.
1) Turn off the power, either all of it, or just the circuit in question, depending on how neatly the CU is wired, how well shielded the neighbouring MCB connection are, how easy the access is, and how comfortable you are with working on one MCB with live ones next to it. I would advise that the default position be to turn it all off, unless you are very happy that you don't need to - it would only be for a few minutes.
If you're not happy with doing any of this, and you really believe that the interference you're getting is because there is a break in one of your circuits, then I guess you'll have to get an electrician in.
2) Disconnect both ends of the live, neutral and earth conductors.
3) Check for continuity of each conductor. If all 3 are OK, then you do not have a break in the ring, you can reconnect everything and start looking for something else to worry about.
4) Only if not, at this stage do you have to start the more time consuming task of finding the break. Reconnect
one end of the cable to the CU, make the other safe with chock-block, and go from socket to socket until you find the first dead one. (If the break was in the earth then you'll have to check with a long-lead multimeter or one of those socket testers that indicates missing earth.)
5) When you've found the last live and first dead sockets, turn off the power again, take them both off the wall, and if the problem isn't obvious (i.e. a cable not connected), disconnect the cable that runs between them and verify that you have found the length of cable with the break.
6) Replace it, put everything back, and repeat steps 1-3 to verify that you've fixed the cable.
7) Hope that this has cured your interference problem, and that it wasn't just that the monitor was too close to the circuit supplying the kitchen anyway....
