Kitchen Sink Live

Bruthal

Merch wrote: »

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)

Thats induction alright, although there wont be enough induced voltage/current in a straight piece of wire to cause shocks. Its barely measurable with a high impedence digital multimeter.

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?

There is an open circuit earth in the socket circuit here, suggested earlier in the thread and now confirmed by the OP. Earth fault appliance can = voltage on its frame, with no low impedence CPC (circuit protective conductor) because the earth is open circuit, to trip RCD or MCB.

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?

Suggested early in the thread, and open earth was the problem, one of the problems anyway.

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?

The RCD needs to be checked here, amongst other things by the look of it.

An extremely severe electrical shock, well beyond a fatal level at 230v, would not trip even a 1 amp MCB, or even get near it. Thats why RCD`s are sensitive to 0.03 amps differential.

M cebee

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?

I doubt it

dunno what those junction boxes are about-never seen the like of it

rcd ,loop impedances,insulation resistances,erronious connections between circuits would be the minimum you'd need to test

Bruthal

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?

No its not. In reality the voltage in houses is induced voltage, as thats how transformerers work, through induction, right down through the electrical grid to the house. But the induction in a floating non connected earth would be infinitely small, but can show up as a fair few volts on a multi meter.

Test from live to floating earth with no appliances on the circuit, and 100v or so is often seen, due to the extreme high impedence of a digital multimeter in a very high impedence circuit(open circut CPC). Test Neutral to this earth, and any voltage seen is due to inductance/capacitance to the floating earth (with no faulty appliances connected). But test neutral to this floating earth with a L- earth fault appliance plugged in or connected to the circuit, and the fault voltage will be seen on the earth compared to a ggod neutral.

(Try even testing from a live to the end of a new reel of cable, and a fair few volts may be seen).

So the readings can vary and be confusing, depending on whats actually connected to this open earth circuit.



An appliance with even a slight live to earth fault plugged into such a socket circuit is what would cause the shocks you talk about.

But when the circuit earth is made good, and the appliance used, if it was a fault in an appliance, the RCD should trip.

Bruthal

M cebee wrote: »

dunno what those junction boxes are about-never seen the like of it

A forgotten circuit/socket or two probably.

They put din rail connectors in and all, and still do a cowboy job of it. PG glands wouldnt of gone amiss at least, and a box with a bit of room.

brightspark

A fault of less than 30mA wouldn't trip the RCD but could still be felt.

M cebee

brightspark wrote: »

A fault of less than 30mA wouldn't trip the RCD but could still be felt.

they can trip above 15mA

M cebee

they should not trip below 0.5 delta N

and any standing leakage on the rcd will reduce the shock level needed to trip it even lower

Bruthal

brightspark wrote: »

A fault of less than 30mA wouldn't trip the RCD but could still be felt.

Yes, but a fault on an appliance connected to an open earth causing a shock to be perceived, should trip a properly functioning RCD when that earth is made good.

And if a live to earth fault is only causing less than 30 ma to flow with a good earth, then contact with this applance will not deliver any shock.

What you`re thinking of is a 30 ma shock through a person, or just below it, not tripping the RCD, but is felt.

A 10 amp fault down a good earth connection, which is 333 times 30 ma, will not be perceived if the earth wire is touched.

Bruthal

M cebee wrote: »

they should not trip below 0.5 delta N

and any standing leakage on the rcd will reduce the shock level needed to trip it even lower

Yes indeed it will, and a neutral-earth short does the opposite, increasing the shock level required to trip it.

Merch

robbie7730 wrote: »

Thats induction alright, although there wont be enough induced voltage/current in a straight piece of wire to cause shocks. Its barely measurable with a high impedence digital multimeter.

Yes, that what I mean, this fault isn't induction


There is an open circuit earth in the socket circuit here, suggested earlier in the thread and now confirmed by the OP. Earth fault appliance can = voltage on its frame, with no low impedence CPC (circuit protective conductor) because the earth is open circuit, to trip RCD or MCB.

I saw the mention of the open circuit, but I cant understand if that is the fault then this should be solved, what I mean is there is another fault still, I wondered had the incorrect MCB been fitted "D" type? ie for motors or flourescent lights? there seems to be a serious fault in the earth of this installation so surely a measurement of the impedence of the earth has to be made overall, there is no mention of the age of the house or the type of earth involved, ie, did someone dig it up with a back hoe??? just throwing the idea out there.


The RCD needs to be checked here, amongst other things by the look of it.
I agree, but that can easily be tested at the consumer unit, I wonder is this circuit even connected to the RCD at all? ok, maybe not a good example, I have two MCB's for kitchen and all other sockets in my house, but the cooker is not connected to the RCD, maybe someone has broken into that circuit for power?

An extremely severe electrical shock, well beyond a fatal level at 230v, would not trip even a 1 amp MCB, or even get near it. Thats why RCD`s are sensitive to 0.03 amps differential.

I am not suggesting the MCB is to protect the individual, but the wring/installation, yes RCD's are to protect the individual, but thought that an earth fault would trip the main circuit breaker as the current would go to a very high level if it was short circuited to earth, thats why Im saying there may be more of a fault with the earth than just at the junction box. Is a "DIN rail" allowed? I was looking with a bit of suprise at that as i have seen plenty of them in factory machines,but if a break in the L,N or Earth is necessary, surely there should be other strip connectors used that are larger/higher rated? suprised as I'm not an electrician, thought it bit suprising that the box was in the bathroom at all, not that I'm faulting the OP.
How is it possible from being at the location to know what type of earth is connected, I have a local earth and I used to think that was my only earth,but I looked into it and I'm sure that is only a backup and that I'm likely connected back at the transformer too. I'd have to look up the earth types. TN-???

The thing is it seems this fault is emanating from somewhere and is worsened because the protection circuit isn't functioning.

I really am wondering what kind of install this is and where it is located? in a recent new build or an isolated development or individual house out in a field somewhere, and what type of earth it has consequently?
The problem doesn't seem to be solved yet, it sounds like the whole installation or quite a few circuits in it might have to be tested?
Maybe an insulation test? maybe nothing intentional was done, like someone stuck a nail through something and subsequently pierced a L and earth connecting them unknowingly?

I'm also left wondering how this was discovered? was there recent work done and then it was noticed? or has it just come to light after possibly having a faulty installation for a long time?

meercat

its possible that this is an apartment pod,which came fully constructed with fitted kitchen and bathroom all completely plumbed and wired back to a service area where the link box is situated.this would have been tested by the electrician in the factory and all was correct.
when the on site electrician connected the socket circuits to his distribution board he missed the earth connection and didnt test the system
the different potentials between the bonded sink and the appliances connected to the unearthed sockets have caused the shock
if this is the case then the link box is way too small as robbie7730 says and this probably contributed to the problem ,but the completion tests should have picked it up
i havnt seen or worked on any of these units but a quick google says this company manufactures such a unit in ireland

http://www.gos.ie/products.php?cat=74&page=Modular

Bruthal

meercat wrote: »

its possible that this is an apartment pod,which came fully constructed with fitted kitchen and bathroom all completely plumbed and wired back to a service area where the link box is situated.this would have been tested by the electrician in the factory and all was correct.
when the on site electrician connected the socket circuits to his distribution board he missed the earth connection and didnt test the system
the different potentials between the bonded sink and the appliances connected to the unearthed sockets have caused the shock
if this is the case then the link box is way too small as robbie7730 says and this probably contributed to the problem ,but the completion tests should have picked it up
i havnt seen or worked on any of these units but a quick google says this company manufactures such a unit in ireland

http://www.gos.ie/products.php?cat=74&page=Modular

It could be that alright, i seen them going in here before. I think it was the bathrooms came as a pod in the ones i seen. I forget now.

meercat

robbie7730 wrote: »

It could be that alright, i seen them going in here before. I think it was the bathrooms came as a pod in the ones i seen. I forget now.

i have seen hotel rooms complete as a pod with small distribution unit installed
all that is required are tails to connect

M cebee

yes that would make sense alright

celtic tiger wiring coming back to bite

many buyers have been let down with self-regulation system

Bruthal

M cebee wrote: »

celtic tiger wiring coming back to bite

No doubt about that. I was talking about the nice nail through the socket circuit during its construction in next doors house a while back that i fixed. Nail between L and E in the T&E, they found a problem when finished wiring because they disconnected the earth in that leg, and bypassed with single core earth, leaving the live nail in the wall. Celtic tiger wiring is right.

Only found because the fella next door changing socket plates, asked me to check them, found free disconnected earth wire from t&e in box, with 230v on it.
Wire a house in a day, doing it properly is secondary.

Merch

robbie7730 wrote: »

No doubt about that. I was talking about the nice nail through the socket circuit during its construction in next doors house a while back that i fixed. Nail between L and E in the T&E, they found a problem when finished wiring because they disconnected the earth in that leg, and bypassed with single core earth, leaving the live nail in the wall. Celtic tiger wiring is right.

Only found because the fella next door changing socket plates, asked me to check them, found free disconnected earth wire from t&e in box, with 230v on it.
Wire a house in a day, doing it properly is secondary.

hmm, you might think I had read that post you mention above, from what i had said earlier in this thread, but thats not the case. Just hashing out the possibilities.

Bruthal

Merch wrote: »

hmm, you might think I had read that post you mention above, from what i had said earlier in this thread, but thats not the case. Just hashing out the possibilities.

No didnt think that, was responding to another poster mentioning celtic tiger wiring, by giving an example of it i encountered last year. And a nail was hammered through a twin and earth next door during construction, and left there, they disconnected the twin and earth`s earth wire from the sockets on both ends of that leg, and ran in a single core earth bypass, rather than replacing the damaged section of t&e, which is what i did with it.

The problem this thread is about is an open circuit earth. With an open circuit earth, no shocks would be received from an appliance plugged into that earthless socket circuit if the appliance or appliances connected were fault free, unless there was damage to the wiring to the socket as well, such as above, or if the floating-non connected socket circuit earth in the junction box was touching a live connection. Ye just never know what ye might see in these installations.

Like i said earlier in the thread, it was likely a long term problem that went un-noticed, until something else went wrong, such as a faulty appliance or other item.

M cebee

looking back now to the time I spent on dublin building sites in pre-reci/ecssa days

the carry-on was shocking bad

self regulation prob didnt change things much

Bruthal

Following on after other peoples horrendous work, nothing on earth is worse. A lot of it is common sense. Unfortunately, common sense doesnt seem all that common at times.

M cebee

yes a bad mistake not to replace the t+e

i've done a good few myself over the years -never started a fire or electrocuted anyone yet thank god

i saw a slab nail (i think it was)through a t+e on an old house with bad wiring

the meter was flying and the circuit fuse was hot

you see some crazy diy stuff when you're rewiring an old house

Bruthal

Most amazing one i seen before was in a house i wired, everything was fine, but some months later i get called, RCD tripping, i go and look. New coving added in some rooms. So i scrape the paint off the coving above a socket i had isolated that leg of as having a neutral-earth short. Sure enough, nail holding the coving up was through the t&e. After removing the nail i test again, still N-E short. Scrape paint off the coving above the next socket on the other end of that same loop. Nail again, remove and fault clear.

I pulled out the piece of t&e and replace.

But what was the chance of 2 nails into 2 drops in 2 different rooms, which both had plastic conduit drops chased into walls, with 2 t&e`s down each deop, and both nails hit the same piece of cable and short the neutral and earth both times.

When i had the cable out you could see the 2 holes 2 meters apart both between the N and E of the cable. I pulled the other cables up a bit to check for damage. Not a mark.

paddymick

robbie7730 wrote: »

Most amazing one i seen before was in a house i wired, everything was fine, but some months later i get called, RCD tripping, i go and look. New coving added in some rooms. So i scrape the paint off the coving above a socket i had isolated that leg of as having a neutral-earth short. Sure enough, nail holding the coving up was through the t&e. After removing the nail i test again, still N-E short. Scrape paint off the coving above the next socket on the other end of that same loop. Nail again, remove and fault clear.

Ive had the same crack with coving guys on more than one occasion...

The last time was a good one I got a call at 7am from the builder who tore lumps out of me because the coving guy tore lumps out of him the night before because his guys couldnt work late as there was no power.

I just knew straight away what was wrong so I went straight to the site and found in the hall that they had nailed a piece of timber around half way up the wall and for some reason had another lenght of timber wedging up the coving on the wall opposite.
Sure enough they went straight through the socket cable..It felt reall nice handing the coving guy the bill that day for repairing the damage:).

Heres two other crackers i came across.
I think theres an idea for a whole dedicated thread here...:D

meercat

paddymick wrote: »

I think theres an idea for a whole dedicated thread here...:D

good idea
a dangerous installation pic thread ???

Bruthal

meercat wrote: »

good idea
a dangerous installation pic thread ???

Yes here is the first one, lethal:D

M cebee

what's the problem with the stairs?

can't see the issue:pac::pac:

Bruthal

M cebee wrote: »

what's the problem with the stairs?

can't see the issue:pac::pac:

They dont look dangerous, but they fooled me:D

.G.

My first company took over the installation in a block of apartments after the original contractor went bust in 08.

This was a couple of the examples of workmanship which probably caused them to go tits up.





and I went onto a site of a house being built for a developer later that year and found this set up by the builder.It was raining that day

Bruthal

superg wrote: »

My first company took over the installation in a block of apartments after the original contractor went bust in 08.

This was a couple of the examples of workmanship which probably caused them to go tits up.



and I went onto a site of a house being built for a developer later that year and found this set up by the builder.It was raining that day

Its unbelievable what some will do.

Merch

superg wrote: »

My first company took over the installation in a block of apartments after the original contractor went bust in 08.

This was a couple of the examples of workmanship which probably caused them to go tits up.





and I went onto a site of a house being built for a developer later that year and found this set up by the builder.It was raining that day

So this (edit) is was a registered electrical contractor? that employs employed registered electricians??
No offense to the many genuine contractors/electricians that are out there, but this is what annoys me as a non-electrician, I wouldn't approach doing stuff like this yet electricians would likely rail against me for saying I prefer/want to do my own work.

meercat

heres my contribution so
some clown decided to bypass the esb meter(Sorry about pic quality)



cant say whether or not this was down to bad connections though




and this gets an award for neatness