Kitchen Sink Live

Bruthal

meercat wrote: »

Turn main switch off and test for voltage
If voltage not present then turn power back on
Turn power back on and then turn tripswitches off individually to determine source

This installation sounds like it possibly has a long term mistake or problem, now shown up by a faulty appliance.

meercat

robbie7730 wrote: »

It sounds like the sockets are fed from another point besides their own MCB, or a ring main to 2 different MCBs. It would be a seperate problem to the earthing problem though.

agree with this

johnpt
"Turned off all circuits except kitchen still getting 120 volts between earth and neutral"

where have you tested between (ie where did you place the probes for the earth and neutral to get 120v)?

M cebee

yes should be easy enough to clear up

fault/faults on the final circuit causing 120volt shock voltage

maybe another problem if one breaker doesn't isolate circuit

prob best to get a inspection

cast_iron

JOHNPT wrote: »

Turned off all circuits except kitchen still getting 120 volts between earth and neutral.

If that also means that the 120v dies when you kill the kitchen circuit while all others are on, then the problem is isolated to the kitchen circuit.

By your description of 2 points having 230v even though you have all legs disconnected, you either missed a point of the circuit, or more likely, there is a joint somewhere hidden that splits to these 2 sockets.

This joint is a likely cause of the problem, or a damaged cable upstream of the 2 remaining live points.

Bruthal

There can be a few causes. 120v between earth and neutral would be a sign of an open earth on a circuit, with a faulty appliance connected to that circuit, or an earth fault in an installation on any circuit, with no neutralising connection at the meter.

If you actualy get a digital meter and test from live to an open ended earth not connected to the earth bar in the DB, or a sink with no earth or copper pipes connected to it, 120v would easily be shown by the meter.

So there are lots of permutations to this. But a socket circuit with a sound earth, and a neutralised installation, should show 0v Neutral to Earth at the socket. (even with reverse polarity at the meter)

Now if the socket circuit itself has reverse polarity, and the CPC of the circuit is open, there is another scenario to read 120v Neutral to Earth at a socket (on a digital multimeter).

meercat

robbie7730 wrote: »

There can be a few causes. 120v between earth and neutral would be a sign of an open earth on a circuit, with a faulty appliance connected to that circuit, or an earth fault in an installation on any circuit, with no neutralising connection at the meter.

If you actualy get a digital meter and test from live to an open ended earth not connected to the earth bar in the DB, or a sink with no earth or copper pipes connected to it, 120v would easily be shown by the meter.

So there are lots of permutations to this. But a socket circuit with a sound earth, and a neutralised installation, should show 0v Neutral to Earth at the socket. (even with reverse polarity at the meter)

Agree
That's why I asked where was he testing from
If he has disconnected the sockets then he may have disconnected the localised bonding to the sink

Bruthal

meercat wrote: »

Agree
That's why I asked where was he testing from
If he has disconnected the sockets then he may have disconnected the localised bonding to the sink

If the socket circuit has an open earth, many assume a digital meter will read 0v live to earth. But it never will. It will be well up toward 100v and likely well above it, due to the meters very high impedence in a now high impedence circuit (open earth), but a person in contact with the same points would have almost 0v across them. And neutral to this earth will also read above 0v if there is a faulty appliance connected to this socket in the kitchen if it has an open earth, and/or no neutralising.

So if this socket circuit is open, then the sink probably has no bonding anyway like you say. Thats if the sink ever had any.

A loop impedence tester into the socket would be handy, but its simple to do quick tests to see if the socket has proper polarity, and a good earth back to the DB, two fundamentals needed to be checked there, as well as making sure only one MCB is supplying the circuit by the sounds of the other problem mentioned.

cast_iron

I's agree with robbie (don't we all:D)

The short version is that there's highly likely to be a bad connection somewhere in the circuit.
I've come across an identical problem before, with the meter giving the same seemingly strange readings. It was a matter of tracking it down to a failed connection at a socket, though could equally have been a bad connection at a joint.

Bruthal

cast_iron wrote: »

I've come across an identical problem before, with the meter giving the same seemingly strange readings. It was a matter of tracking it down to a failed connection at a socket, though could equally have been a bad connection at a joint.

Last time i seen similar was when the house had over 300v at the sockets. So straight away i was onto the esb suggesting it was probably a neutral failure. It was the neutral gone at the mini pillar. Switching on a heavy item such as a cooker would transfer more of the voltage to another affected house. Not the problem here with 230v measured of course.

Everything in the house was ruined.

This type of problem is where the bonding of all metal is important, with neutralised installations.

A good chance of a hidden joint as part of the problem in this thread alright.

M cebee

robbie7730 wrote: »

There can be a few causes. 120v between earth and neutral would be a sign of an open earth on a circuit, with a faulty appliance connected to that circuit, or an earth fault in an installation on any circuit, with no neutralising connection at the meter.

If you actualy get a digital meter and test from live to an open ended earth not connected to the earth bar in the DB, or a sink with no earth or copper pipes connected to it, 120v would easily be shown by the meter.

So there are lots of permutations to this. But a socket circuit with a sound earth, and a neutralised installation, should show 0v Neutral to Earth at the socket. (even with reverse polarity at the meter)

Now if the socket circuit itself has reverse polarity, and the CPC of the circuit is open, there is another scenario to read 120v Neutral to Earth at a socket (on a digital multimeter).

problem is confined to kitchen

he got a severe shock

so obviously not phantom voltage or neutralizing

there's usually a few permutations on the obvious alright

meercat

M cebee wrote: »

problem is confined to kitchen

he got a severe shock

so obviously not phantom voltage or neutralizing

there's usually a few permutations on the obvious alright

wouldnt be too sure about that(most likely though)

different potentials between earths

there are probably no other locations in the installation where there are appliances that he could get different potentials between earths

M cebee

dso neutral bad connection

or no neutralizing+fault

everything connected to met is live

Bruthal

M cebee wrote: »

problem is confined to kitchen

he got a severe shock

so obviously not phantom voltage or neutralizing

there's usually a few permutations on the obvious alright

I was talking about a few causes of the 120v between neutral and earth at the socket. And i mention the multimeter displaying a good voltage in some situations because it can add to the confusion.

The socket circuit is the first place to look, and test, when there is a PD between that socket neutral and earth.

A severe shock from 120v would be unlikely.

No neutralising on a bonded system that should be neutralised (no main RCD) and an earth fault could leave up to the 230v between an earthed appliance and a non bonded but indirectly earthed sink etc.

The kitchen is the only place the shock problem has been noticed. It may not be confined to there.

M cebee

I saw 39v on some 2 wayed led downlights today

measured with fluke dmm
flicker dissapeared when I stuck in 1 halogen bulb

not quite sure ,i assume its induced voltage

Bruthal

If i was to just take a wild guess, id have a go at earth missing on socket circuit to kitchen, and earth fault appliance.

But a few quick tests should find the actual problem, but the actual location might be harder to find, such as possible hidden JB etc.

Merch

While I'm not an electrician, I started reading the thread earlier and came back to see if a solution had been found,

from an outside perspective, I assume other possibilities have been considered, maybe something an electrician wouldnt consider (or maybe they would?)
so
Has there been any recent work down, sockets? even lighting? maybe someone had previously powered lights through sockets or vica versa?? could try switch off the lighting circuit too to test? or maybe there is a fault in an individual appliance? maybe someone has changed a plug/socket and has been wired in correctly, re N, L, E? (that may have been discussed, I admit I didnt read the thread thoroughly, just giving my 2p's worth)

meercat

were all waiting for the solution:D

good points merch but i would hope the op has ruled them all out by now

Bruthal

M cebee wrote: »

I saw 39v on some 2 wayed led downlights today

measured with fluke dmm
flicker dissapeared when I stuck in 1 halogen bulb

not quite sure ,i assume its induced voltage

Yea you will see that on cfl`s as well, or with no bulb fitted. The induced voltage in the strapper thats off appears on the live terminal of the bulb fitting of cfl`s and electronic fittings because the impedence through them to the neutral terminal is so high.

Fit an incandescent and the impedence is now relatively very low, making a good connection between the switched off live terminal of the fitting (and the off strapper), and neutral. So it shows no induced voltage.

Strappers show this induced voltage because they normally follow the same route, although because there is no current flow with the light off, capacitance is probably more likely. It is enough to sometimes dimly light phase testers too.

M cebee

robbie7730 wrote: »

M cebee wrote: »

problem is confined to kitchen

he got a severe shock

so obviously not phantom voltage or neutralizing

there's usually a few permutations on the obvious alright

I was talking about a few causes of the 120v between neutral and earth at the socket. And i mention the multimeter displaying a good voltage in some situations because it can add to the confusion.

The socket circuit is the first place to look, and test, when there is a PD between that socket neutral and earth.

A severe shock from 120v would be unlikely.

No neutralising on a bonded system that should be neutralised (no main RCD) and an earth fault could leave up to the 230v between an earthed appliance and a non bonded but indirectly earthed sink etc.

The kitchen is the only place the shock problem has been noticed. It may not be confined to there.

ya I must go back and check thread

maybe it was just a good tingle or a bad rattle

M cebee

robbie7730 wrote: »

cast_iron wrote: »

I've come across an identical problem before, with the meter giving the same seemingly strange readings. It was a matter of tracking it down to a failed connection at a socket, though could equally have been a bad connection at a joint.

Last time i seen similar was when the house had over 300v at the sockets. So straight away i was onto the esb suggesting it was probably a neutral failure. It was the neutral gone at the mini pillar. Switching on a heavy item such as a cooker would transfer more of the voltage to another affected house. Not the problem here with 230v measured of course.

Everything in the house was ruined.

This type of problem is where the bonding of all metal is important, with neutralised installations.

A good chance of a hidden joint as part of the problem in this thread alright.

ive seen it happen
a lot to be said for external power supplies on equipment when this happens-a simple swop

im sure a lot of undervoltage and overvoltage damage goes unreported

Bruthal

M cebee wrote: »

ive seen it happen
a lot to be said for external power supplies on equipment when this happens-a simple swop

im sure a lot of undervoltage and overvoltage damage goes unreported

Yea id say it does.

JOHNPT

Problem fixed. There was a junction box in a cupboard in the bathroom - which was behind kitchen. See pictures. Cables were joined in this - hence one cable from fuseboard to junction box - was joined to seperate cables feeding kitchen sockets - cables probably damaged or cut too short initially. Earth connections were very bad hence what i was picking up was a floating earth. The earth connection you can see in picture is new connectors i put in

Thanks for all the help and replies.

meercat

robbie7730 wrote: »

If i was to just take a wild guess, id have a go at earth missing on socket circuit to kitchen, and earth fault appliance.

But a few quick tests should find the actual problem, but the actual location might be harder to find, such as possible hidden JB etc.

spot on robbie

induced voltage as it seems the earth wire was not connected to the kitchen socket circuits

M cebee

meercat wrote: »

robbie7730 wrote: »

If i was to just take a wild guess, id have a go at earth missing on socket circuit to kitchen, and earth fault appliance.

But a few quick tests should find the actual problem, but the actual location might be harder to find, such as possible hidden JB etc.

spot on robbie

induced voltage as it seems the earth wire was not connected to the kitchen socket circuits

I doubt it

the induced voltge alone doesnt deliver shock

an additional fault is needed

pretty much as discussd

Bruthal

M cebee wrote: »

I doubt it

the induced voltge alone doesnt deliver shock

an additional fault is needed

pretty much as discussd

Indeed, open circuit earth with earth fault on appliance likely, if there where shocks being received.

M cebee

might still be fault current here
dunno is rcd even working

I would be advising complete inspection
considering the cockups already found

cast_iron

meercat wrote: »

spot on robbie

Ah now hold on, I said it first :P

cast_iron wrote:

...or more likely, there is a joint somewhere hidden that splits to these 2 sockets.

This joint is a likely cause of the problem...

Doesn't solve the shock issue though.

meercat

cast_iron wrote: »

Ah now hold on, I said it first :P
Doesn't solve the shock issue though.

mea culpa

JOHNPT

You only got a shock when you touched dishwasher or washing machine and then touched the sink (which was bonded) at the same time. Is this not possible with induced voltage?

Merch

JOHNPT wrote: »

You only got a shock when you touched dishwasher or washing machine and then touched the sink (which was bonded) at the same time. Is this not possible with induced voltage?

Induced voltage? induction is when a a magnetic field is formed and collapses, a voltage is induced (in a coil), have to look it up to be exact (i should know)
to me
what you are saying sounds like an earth fault in either/both of those appliances?
If there is an earth fault, shouldn't the main breaker trip?

The earth of the plug of either of those devices should make continuity with the metal case (where there is bare metal or at the point an earth wire is connected),
Possibly continuity of the earths at the sockets where these appliances are connected and some other earth should be checked?

sounds dangerous,
I've read of this before, where there is enough current to give a shock (and depending on the person, the effects vary) but not trip the breaker, is the right type of breaker installed?