Kitchen Sink Live

JOHNPT

I was called to an apartment late yesterday whereby the tenants are getting an electric shock from kitchen appliances. It was reading approx 120volts between dishwasher & sink. Same voltage occurred between washing machine & sink. I disconnected all sockets in kitchen (apart from fridge which is integrated) - however although it appears its a radial circuit - (20 amp MCB & only one circuit from top MCB) - I am getting 230 volts live/neutral in two separate points (under-sink socket and counter top socket) also there is 18 volts in earth wire at both these points.

Seems very strange set up

Any advice on what problem could be or what steps undertake first

Thanks

2011

JOHNPT wrote: »

I was called to an apartment late yesterday whereby the tenants are getting an electric shock from kitchen appliances. It was reading approx 120volts between dishwasher & sink. Same voltage occurred between washing machine & sink. I disconnected all sockets in kitchen (apart from fridge which is integrated) - however although it appears its a radial circuit - (20 amp MCB & only one circuit from top MCB) - I am getting 230 volts live/neutral in two separate points (under-sink socket and counter top socket) also there is 18 volts in earth wire at both these points.

Seems very strange set up

Any advice on what problem could be or what steps undertake first

Thanks

Carry out an insulation resistance test on all circuits.

Clearly there is an issue with equipotential bonding here as well as a live conductor shorting to something conductive connected to the sink.

This may be nothing to do with kitchen sockets.
Normally the RCD would operate if a socket circuit was causing this.

Turn off all circuits at the board one by one unytil the problem goes.
This will idebtify the problem circuit.

sparcocars

JOHNPT wrote: »

I was called to an apartment late yesterday whereby the tenants are getting an electric shock from kitchen appliances. It was reading approx 120volts between dishwasher & sink. Same voltage occurred between washing machine & sink. I disconnected all sockets in kitchen (apart from fridge which is integrated) - however although it appears its a radial circuit - (20 amp MCB & only one circuit from top MCB) - I am getting 230 volts live/neutral in two separate points (under-sink socket and counter top socket) also there is 18 volts in earth wire at both these points.

Seems very strange set up

Any advice on what problem could be or what steps undertake first

Thanks

It sounds like it could also be reverse polarity. If there was work done by the esb recently then reverse polarity might be getting sent into the apartment. But i the apartment is in a block then the rest of the apartments could be the same. Confirm that the neutral is actually a neutral and that the phase is actually a phase.
If there was a just a short from liveto earth then the mcb and rcd would trip. If neutral shorted to earth then the rcd would be tripping as soon as current is flowing the circuit.

Set up an independant earth wire using a piece of wire into the ground outside and use it with a multimeter to confirm your phase and neutral. Don't just test between phase and earth or neutral and earth at the back of the socket as if it is reverse polarity the earth would be at the same potential as the neutral because of the neutralising link therefore you would get 0 volts between neutral and earth even though the neutral is actually live.

meercat

did you check neighbouring appartments
problem most likely to be detected at the fuseboard
i would check for a burnt out neutral somewhere on the system(its possibly in another apartment or on the metering system
johnpt do not do this if you are not an electrician
to locate fault
turn main switch off
open the cover of consumer unit
check for voltage between earth and neutral bus bars
if you have voltage
disconnect the 10sq earths individually and check which one is the problem
(probably the main incoming earth)
if thats the problem then esbn emergency call

JOHNPT

Ok will do above Meercat. Very strange that ELCB didnt trip - was quite a shock when touching dishwasher & sink. Also 2011 good point - turn off each individual circuit see will problem disappear.

meercat

check also that the system is bonded correctly
the earthing system may be live(reverse polarity,as sparcocars said)but there should be no differential between the appliances and the sink

meercat

sorry

M cebee

assuming the problem is confined to the kitchen sink area

sounds like there's an issue with the radial circuit cpc(earth) and an appliance fault
at the same time


loop impedance tester might tell you quickly

2011

JOHNPT wrote: »

Ok will do above Meercat. Very strange that ELCB didnt trip - was quite a shock when touching dishwasher & sink. Also 2011 good point - turn off each individual circuit see will problem disappear.

The ELCB (or RCD) would only operate if the problem was caused by a circuit protected by it and the current would have to be in excess of 30mA (normally). It is also possible that the RCD was faulty.

2011

sparcocars wrote: »

Set up an independant earth wire using a piece of wire into the ground outside and use it with a multimeter to confirm your phase and neutral. Don't just test between phase and earth or neutral and earth at the back of the socket as if it is reverse polarity the earth would be at the same potential as the neutral because of the neutralising link therefore you would get 0 volts between neutral and earth even though the neutral is actually live.

Alternatively with most multimeters you can check polarity.

Bruthal

JOHNPT wrote: »

I was called to an apartment late yesterday whereby the tenants are getting an electric shock from kitchen appliances. It was reading approx 120volts between dishwasher & sink. Same voltage occurred between washing machine & sink. I disconnected all sockets in kitchen (apart from fridge which is integrated) - however although it appears its a radial circuit - (20 amp MCB & only one circuit from top MCB) - I am getting 230 volts live/neutral in two separate points (under-sink socket and counter top socket) also there is 18 volts in earth wire at both these points.

Seems very strange set up

Any advice on what problem could be or what steps undertake first

Thanks

The first thing I would check for is continuity of the socket circuit earth to the DB. An open circuit earth and an earth fault on an appliance would be one cause of the problems you found (amongst others). A loop impedence test would show that up.

How did you find 18v at the socket earths? 18v between socket earth and what?

liveandnetural

this is i dangrous fault!!!!!!!!!! and asking for help on the boards is not a way to deal with it


please tell you havent left tennents in a appartment with a serious fault still in place:mad:

M cebee

i would hope not

john is an electrician

JOHNPT

I know its a serious fault hence reason I posted - all above electricians have different steps they would undertake first to try and find the fault. Less of your condescending tone - if you dont want to give your opinion or dont know what steps you would do first thats fine.

meercat

JOHNPT wrote: »

I know its a serious fault hence reason I posted - all above electricians have different steps they would undertake first to try and find the fault. Less of your condescending tone - if you dont want to give your opinion or dont know what steps you would do first thats fine.

Johnpt
I think anyone who posted was trying to help
It was just pointed out how serious a problem it is and that it shouldn't be left that way
Mcebee pointed out that you are an electrician(in you defence) and hoped you wouldn't
Have you resolved this problem and what have you found
Cheers

2011

liveandnetural wrote: »

this is i dangrous fault!!!!!!!!!! and asking for help on the boards is not a way to deal with it


please tell you havent left tennents in a appartment with a serious fault still in place:mad:

I am confident that even if John has not solved this problem yet that he would have left the installation in a safe condition.

Threads like this are good, we have all learnt on this forum from discussing problems such as this.

Bruthal

2011 wrote: »

Threads like this are good, we have all learnt on this forum from discussing problems such as this.

Couldnt agree more.

2011

robbie7730 wrote: »

Couldnt agree more.

What do you mean by that???
I was looking forward to a Sunday row with you :D:D

paddymick

robbie7730 wrote: »

Couldnt agree more.

I was just going to say the same Robbie..

Bruthal

2011 wrote: »

What do you mean by that???
I was looking forward to a Sunday row with you :D:D

:D:D

paddymick

2011 wrote: »

What do you mean by that???
I was looking forward to a Sunday row with you :D:D

Thats when I like to sit here in the background with the popcorn:D

Bruthal

paddymick wrote: »

Thats when I like to sit here in the background with the popcorn:D

I got popcorn myself the last time:D

M cebee

problem with dso neutral or dso reverse polarity would affect the whole installation i would say

-not just the sink area


reverse polarity on the tails or downstream would go un-noticed alright ,protective devices on neutral

rcd would still operate normally

meercat

M cebee wrote: »

problem with dso neutral or dso reverse polarity would affect the whole installation i would say

-not just the sink area


reverse polarity on the tails or downstream would go un-noticed alright ,protective devices on neutral

rcd would still operate normally

Agree
Maybe the problem is in the whole installation alright and the sink is not bonded creating a different potential
It's only noticeable here because of the appliances
Full test of installation is required

M cebee

appliance not earthed
appliance fault

appliance live with respect to earth and local bond(if fitted)

i would have thought


the local bond should prevent shock a lot of time ,but not always

i suppose it could be a few things

M cebee

meercat wrote: »

Agree
Maybe the problem is in the whole installation alright and the sink is not bonded creating a different potential
It's only noticeable here because of the appliances
Full test of installation is required

reverse polarity on the tails is a scary one

L-E short circuits can back up the cut-out fuse and mcbs don't isolate circuits

there was a kitchen man killed after a spark connected tails reverse and walked away-according to my inspector

i think he was messing with a cooker and turned off mcb

electrician should have just plugged in his loop impedance tester if he was in major hurry


mind you i've had a few near misses through carelessness myself-easily done if you don't go by the book

liveandnetural

while were wait for johnpt to reply www.youtube.com/watch?v=1EBfxjSFAxQ

M cebee

liveandnetural wrote: »

while were wait for johnpt to reply www.youtube.com/watch?v=1EBfxjSFAxQ

you're great crack

JOHNPT

Turned off all circuits except kitchen still getting 120 volts between earth and neutral. Disconnected main earth bonding at fuseboard still the same. All other sockets outlets in apartment are fine 0 volts between earth and neutral. Kitchen has only one circuit (one cable from top of 20amp MCB) - there is 2 cables at each socket point but still when all cables disconnected I am getting 230 volts between live and neutral at two seperate socket outlets??

If anyone here thinks they can solve problem can u PM me - apartment is in Kilmainham area

meercat

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

Bruthal

JOHNPT wrote: »

Turned off all circuits except kitchen still getting 120 volts between earth and neutral. Disconnected main earth bonding at fuseboard still the same. All other sockets outlets in apartment are fine 0 volts between earth and neutral. Kitchen has only one circuit (one cable from top of 20amp MCB) - there is 2 cables at each socket point but still when all cables disconnected I am getting 230 volts between live and neutral at two seperate socket outlets??

If anyone here thinks they can solve problem can u PM me - apartment is in Kilmainham area

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.

Switch every MCB in the board off. Test sockets in kitchen. Then find which one(s) bring the sockets in kitchen on.

Plug in a loud radio so you dont have to keep running in to check. That way you can switch each MCB on and back off, so you only have one on at a time. Go through them all even after you switch the kitchen one on and off.

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