Socket with earth fault
MuddyFork
washing machine socket in the kitchen, the socket tester said there was an
earth fault.
When checked with a multi-meter, I can't measure a voltage between earth and
either live or neutral at the socket, so presumably the earth is simply
disconnected. The live and neutral are OK at the socket, because appliances
work when plugged in.
The socket is fed by a double pole switch on the other side of the kitchen,
so I guess the concealed cable in between is damaged. The earth at the
switch is OK. I've tried a cable detector
(http://www.screwfix.com/app/sfd/cat/products.jsp?id=49160&ts=85511), but
there seems to be a lot of other metal in the wall (perhaps foil-backed
plasterboard), so I haven't been able to trace the cable yet.
My next step is to start cutting holes in the plasterboard and removing wall
tiles in an attempt to find the cable fault.
Is there anything less destructive I could try?
Harry Bloomfield
Might it not be easier/simpler to find an earth at another socket on
the same circuit and loop it across, rather than attempting to find the
break?
A broken earth in the cable is the least likely. Most likely are breaks
near the ends. Try tugging the earth wire at its ends.
--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk
Jim K
daft question but it's not clear:- you have had the socket off and
checked the earth wire is connected haven't you?
if not do so and (safely) test the continuity of the earth wire from
the switch to the socket? then you;ll *know* you have a cable fault or
not...??
Jim K
Dave Plowman (News)
Disconnect the cable and check the ECC with your meter first?
Never assume a fault *must* be in the most awkward place.
If your test meter leads won't reach connect the ECC to say the neutral at
one end and measure between them at the other. After disconnecting,
obviously.
--
*Could it be that "I do " is the longest sentence? *
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Lobster
> I've recently bought a house, and when I checked an under-the-worktop
> washing machine socket in the kitchen, the socket tester said there was an
> earth fault.
> When checked with a multi-meter, I can't measure a voltage between earth and
> either live or neutral at the socket, so presumably the earth is simply
> disconnected. The live and neutral are OK at the socket, because appliances
> work when plugged in.
You don't say, but at the risk of stating the bleedin' obvious,
presumably you've unscrewed the socket faceplate to check whether the
earth wire has simply become disconnected from its terminal?
If not (with the power turned off at the mains), I would next try
disconnecting all the terminals within both the socket and switch, and
check for continuity between the two, of all three wires (do you have a
cheapo voltmeter, or a battery/bulb combo?) That would at least
definitively diagnose the problem, if it's what you suspect.
What is the cable route betweem socket and switch like?
David
Dave Liquorice
> The earth at the switch is OK.e cable fault.
>
> Is there anything less destructive I could try?
Continuity of the earth between the cable end in the switch and same
cable end in the socket back boxes? If the earth is broken and it not
obvious when you waggle the cable ends I'd be a bit concerned that
there is a nail or something slap down the center of the cable.
While you are at it check that the DP switch you think is controlling
both legs of the cable really is controlling both legs not just one
of them, particularly if there are a number of cables in the same
back box (grid switch?)
--
Cheers
Dave.
MuddyFork
news:7P4eo.32005$S_1.19575@hurricane...
Thanks for the replies. I should have said that I've already removed the
socket and the switch from their back-boxes to check for loose connections.
The idea of doing a continuity test on the 3 wires with the power switched
off is a good one - I will try that.
Shortest route between the socket and the switch involves passing behind a
sink and several kitchen cabinets, and a layer of wall tiles. Presumably
that is the route the electrician took when the house was built 15 years
ago.
Jim K
> "Lobster" <davidlobsterpot...@hotmail.com> wrote in message
to me at least, it seems a bit odd why anyone would want a socket
controlled by a distant switch *across* a room?
could be the tip of a "homemade" bodge job here....go carefully!
Jim K
cynic
You have of course checked continuity from earth terminal to "earth
pin" at the socket? a simple faulty socket is not beyond the realms of
possibility.
Peter Parry
wrote:
>The socket is fed by a double pole switch on the other side of the kitchen,
>so I guess the concealed cable in between is damaged. The earth at the
>switch is OK.
Have you tried measuring continuity between the earth cable (not the
screw connector) at the switch and the socket? Cable faults are
relatively unusual unless the cable runs in notched beams and someone
has nailed a floorboard down and put the nail through the cable.
Bill
Bloomfield <harry...@NOSPAM.tiscali.co.uk> writes
>Might it not be easier/simpler to find an earth at another socket on
>the same circuit and loop it across, rather than attempting to find the
>break?
>
damage has happened to the cable?
--
Bill
Andy Dingley
> to me at least, it seems a bit odd why anyone would want a socket
> controlled by a distant switch *across* a room?
I've had those in kitchens where the dishwasher, fridge and washing
machine are semi-permanently wired, and the control switches have been
bundled to one place.
Jim K
interesting...
would that be allowed under todays regs? isn;t there some mention of
"local" control of appliances presumably so it's intuitive how you
turn the smoking washer/etc off in a hurry for e.g.
Jim K
js.b1
> interesting...
> would that be allowed under todays regs? isn;t there some mention of
> "local" control of appliances presumably so it's intuitive how you
> turn the smoking washer/etc off in a hurry for e.g.
Within 2m of the appliance, which in a small kitchen may be on the
opposite wall.
Some people like a single isolator for all the sockets in a kitchen on
safety grounds, and others with very small fingers use grid switches.
John Rumm
> I've recently bought a house, and when I checked an under-the-worktop
> washing machine socket in the kitchen, the socket tester said there was an
> earth fault.
> When checked with a multi-meter, I can't measure a voltage between earth and
> either live or neutral at the socket, so presumably the earth is simply
> disconnected. The live and neutral are OK at the socket, because appliances
> work when plugged in.
Sounds possible...
> The socket is fed by a double pole switch on the other side of the kitchen,
> so I guess the concealed cable in between is damaged. The earth at the
First thing you need to do is a visual inspection - have a peek behind
the switch and the socket and look for loose wires.
> switch is OK. I've tried a cable detector
> (http://www.screwfix.com/app/sfd/cat/products.jsp?id=49160&ts=85511), but
> there seems to be a lot of other metal in the wall (perhaps foil-backed
> plasterboard), so I haven't been able to trace the cable yet.
>
> My next step is to start cutting holes in the plasterboard and removing wall
> tiles in an attempt to find the cable fault.
> Is there anything less destructive I could try?
Why not check to see if the cable is actually at fault before you start
wrecking the kitchen?
Assuming the visual check looks ok, disconnect the cable (having turned
off the power obviously) at both the switch and the socket. Short all
three conductors together at one end, and then measure resistance
between them at the other. Only if you then have an open circuit do you
know there is a genuine cable problem (assuming you are *sure* the cable
only goes from the switch to the socket and nowhere else).
--
Cheers,
John.
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| John Rumm - john(at)internode(dot)co(dot)uk |
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MuddyFork
news:f4adneY4QL8BbeTR...@brightview.co.uk...
Thanks for all the replies.
I have now disconnected the cable at both ends, and measured the resistance
of each of the 3 conductors. The live and neutral are fine, but the earth is
open circuit. I've tried tugging on the earth wires at both ends, and both
seem undamaged, so it seems to me that the earth conductor is broken
somewhere in the middle, even though that seems unlikely.
Dave Plowman (News)
MuddyFork <ewf...@fewf.efwef> wrote:
> I have now disconnected the cable at both ends, and measured the
> resistance of each of the 3 conductors. The live and neutral are fine,
> but the earth is open circuit. I've tried tugging on the earth wires at
> both ends, and both seem undamaged, so it seems to me that the earth
> conductor is broken somewhere in the middle, even though that seems
> unlikely.
I'd look along the likely run for any fixing etc that may have pierced it.
--
*Why is "abbreviated" such a long word?
js.b1
with overheated terminals or plaster splodged into a taped up
chocolate block connector?
ARWadsworth
> Thanks for all the replies.
> I have now disconnected the cable at both ends, and measured the
> resistance of each of the 3 conductors. The live and neutral are
> fine, but the earth is open circuit. I've tried tugging on the earth
> wires at both ends, and both seem undamaged, so it seems to me that
> the earth conductor is broken somewhere in the middle, even though
> that seems unlikely.
Unfortunatley it is quite common. People drill through cables breaking the
CPC.
Have you got any other under worktop sockets that you could take a spur from
and save you the effort of replacing the damaged cable?
--
Adam
Lobster
> In article <4c7a35eb$0$17434$bed6...@gradwell.net>,
> MuddyFork <ewf...@fewf.efwef> wrote:
>> I have now disconnected the cable at both ends, and measured the
>> resistance of each of the 3 conductors. The live and neutral are fine,
>> but the earth is open circuit. I've tried tugging on the earth wires at
>> both ends, and both seem undamaged, so it seems to me that the earth
>> conductor is broken somewhere in the middle, even though that seems
>> unlikely.
>
> I'd look along the likely run for any fixing etc that may have pierced it.
Seems the most plausible cause... either that, or as someone else has
alluded to, there could be a poorly wired join of two lengths of cable.
Either way, I wouldn't be trusting that the L & N wires are 100% OK -
there could be a short circuit waiting to happen. I think you need to
trace the positiom of the fault, ot isolate the length of damaged cable
and run a new length in its place.
David
John Rumm
> "John Rumm"<see.my.s...@nowhere.null> wrote in message
>> > Assuming the visual check looks ok, disconnect the cable (having turned
>> > off the power obviously) at both the switch and the socket. Short all
>> > three conductors together at one end, and then measure resistance
>> > between them at the other. Only if you then have an open circuit do you
>> > know there is a genuine cable problem (assuming you are*sure* the cable
>> > only goes from the switch to the socket and nowhere else).
> Thanks for all the replies.
> I have now disconnected the cable at both ends, and measured the resistance
> of each of the 3 conductors. The live and neutral are fine, but the earth is
> open circuit. I've tried tugging on the earth wires at both ends, and both
> seem undamaged, so it seems to me that the earth conductor is broken
> somewhere in the middle, even though that seems unlikely.
A damaged or crushed cable seems most likely then...
Short of exotic test equipment like a TDR setup you may be stuck. Any
place you could route an alternative?
m...@privacy.net
John Rumm <see.my.s...@nowhere.null> wrote:
>
> A damaged or crushed cable seems most likely then...
>
> Short of exotic test equipment like a TDR setup you may be stuck. Any
> place you could route an alternative?
>
My upstairs lighting cable was discovered to have a broken earth. This was
due to the original builders crushing the cable between a floorboard and the
breeze block wall. One of the other conductors was also damaged, and came
apart with little provocation.
If it is a broken earth conductor it needs to be found and repaired, or the
complete cable run replaced. Do not use a cable with one suspect core, there
will almost certainly be more damage..
--
B Thumbs
Change lycos to yahoo to reply
John Rumm
> Shortest route between the socket and the switch involves passing behind a
> sink and several kitchen cabinets, and a layer of wall tiles. Presumably
> that is the route the electrician took when the house was built 15 years
> ago.
There is no reason your replacement cable has to run the same route
though - it could be surface wired behind the cupboards for example to
make life easier.
John Rumm
When I rewired my former neighbours house a few years back, I found a
standard 5A junction box joining three flexes, just buried in the
plaster plaster about a foot above the kitchen sink! (not sure if he
owned up to that one or not ;-)