Electrical wiring in older flat

Hi, I'm having a major headache.

I live in a 60's built maisonette, and have discovered that none of the upstairs sockets are grounded. I was replacing a couple of socket plates a while ago, and noticed there were only two wires (RED & BLACK) connected to the appropriate terminals within the socket, but no earth wire. The red&black wires disappear down a conduit pipe which appears to be metal. Downstairs however all seems fine and the electricity meter & fuse box are both grounded from the outside.

Is this sort of thing easily sorted or are we talking major rewiring (and expense)? Would stuff have to be ripped out of walls?

Any help would be really appreciated.

Bart

Reply to
Korgi
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In the '60s there was a requirement for three pin sockets to be earthed. It's likely the steel conduit is providing the earth. However, this depends on the socket being securely fixed to the box as the screws etc are the earth path. I'd be inclined to supplement this with an earth terminal fitted to the backing box with a tail from that to the socket terminal.

Reply to
Dave Plowman (News)

On 27 Jan 2006 03:29:48 -0800 someone who may be "Korgi" wrote this:-

Have you tested them, or do you just think this?

The conduit is undoubtedly also the protective conductor (earth).

The first thing I would do is get/borrow a socket tester and plug it in to each socket. These testers don't do a thorough test, but do give a good indication.

The second thing I would do is connect a short length of green and yellow insulated wire from the earth terminal of the socket to the terminal there should be in the box. This guards against the screws, which are the protective conductor, becoming loose or falling out.

The third thing I would do/have done is a proper electrical test on the wiring. This will thoroughly test the soundness of the conduit, amongst other things. What work, if any, needs to be done depends on the results of this test. It may be that no more work needs to be done, other than a test in some years time. This can be a difficult area. Some people doing such tests will recommend all sorts of unnecessary work, simply in the hope that they can boost their profits.

Reply to
David Hansen

Cheers for the advice - I actually stumbled on this issue by accident, when I noticed unusually loud "humming" sound coming from a guitar pickup connected to a tape recorder in the upstairs bedroom. Having read up about "ground loops", I thought I'd try connecting the outer metal casing of the recorder to a mains water pipe in the adjacent bathroom, and.... the hum had disappeared. I then plugged the said recorder into an extension cord connected to a downstairs socket, and again to my delight, no hum. So I tried all the sockets in the flat that way and found that all the upstairs sockets were noisy, and all the downstairs ones were silent.

Bart.

Reply to
Korgi

On 27 Jan 2006 06:01:26 -0800 someone who may be "Korgi" wrote this:-

Then I suggest you get the socket tester rapidly and see what it shows, then a full test. It may be that a joint has failed/is failing in the conduit going upstairs.

Reply to
David Hansen

I suspect this wireing is very old and could be getting near to the end of it's useful life.

I'd suggest getting an independant electrician to do a periodic inspection of the wiring. Don't go with your local elec supply company, they'll more than likely just send a salesman round.

Reply to
zikkimalambo

U might as well check format and wiring practice of all downstairs outlets, too. Essentially, the conduits of both floors should be bonded as one steel network, and a necessary link between storeys is adrift. How many 13A sockets are u talking about? Are they single- or double-ganged? Are they all routed in conduit runs? Are they at present connected by two pairs of red and black wires of at least 20A gauge (which would indicate a Ring mains pattern)? Or is there just a pair of wires in each conduit run, implying spurs taken off a major cct? If the latter style, naughty - there may well be overload problems. If there is no functional Earth present throughout when you plugged in tape recorder upstairs, the integrity of -each- conduit and backbox appearance (and of any hidden metal junction boxes) needs to be tested rigorously all the way from supply E in Fuse Box! Are those fuse wires of correct gauge (ie, not botched)? As a previous person gas written, assuming each conduit continuity -has been- proven sound, u should add 8" of green/yellow, stranded 20A wire from back box brass terminal and the earth terminal of power outlet. Jim

Reply to
Jim Gregory

It could be the earth connection to the conduit has failed - or the conduit has been cut into to add sockets, etc. But this needs proper checking either way. If, for example, the earth to the conduit is missing, a faulty appliance could result in *other* things on that circuit becoming live and dangerous - ie worse than no earths at all on individual sockets.

Reply to
Dave Plowman (News)

If it was built in the 1960s and still uses the conduit as an earth, the chances are that the wiring is original. If so, it is time it was all replaced anyway.

Colin Bignell

Reply to
nightjar

It could well be PVC and still in good condition - although of course there are other reasons to re-wire. If it's rubber I'd agree.

Reply to
Dave Plowman (News)

60's PVC should be fine. The earth fault loop impedance needs testing. If it was a LA build, the screwed conduit would have had to have painted threads, which will have prevented corrosion over the years and resistance should still be low. As someone else said, the earth continuity could have been damaged by subsequent modifications though.

The wiring accessories (switches, sockets, fusebox, etc) in a

60's installation should be considered to be in need of a good inspection though. Many of these will be at the end of their life, but that's a relatively easy thing to fix. The other issue could be lack of sockets (again, a LA build specified many more than private builds would have had at that time).
Reply to
Andrew Gabriel

Agreed, but IME two wire and conduit is most often rubber.

Colin Bignell

Reply to
nightjar

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