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.