240v from Sink

[adrian.groves]

Hi,

I have had a 3 quite heavy shocks when touching my sink tap. One when touching the tap and dishwasher, the other when touching the tap and kettle. It does not trip the RCBO.

I have connected a multimeter to the tap and it maintained 240v. It also reads 240v when connected to the tap and dishwasher.

I cannot see any bonding on the sink and was wondering if that is the only problem.

Does anybody have any ideas?

Thanks

 

[Newboy]

yes - call an electrician NOW

 

[eveares]

As newboy said, but have you tried isolating different circuits to see what one of them is causing the sink to become live by using your multi meter. A number of things could be causing it.

Is it a recent problem related to any recent works you may have had done?

 

[adrian.groves]

The 240v goes away when I isolate that side of the kitchen so I will leave that switched off for now. We have had a lot of decorating done but no new wiring.

 

[davelx]

The 240v goes away when I isolate that side of the kitchen so I will leave that switched off for now. We have had a lot of decorating done but no new wiring.

Screw through a cable somewhere? Any new plumbing? - pipe clips screwed to the wall that might have gone through a cable , that sort of thing?

 

[bernardgreen]

There are two possibilities.

1) The sink and pipework connected to it 230 volts above GROUND

2) The sink is at GROUND and the "Earth" to the kettle and dishwasher is at 230 volts.

If 2) then the Earth connection to those sockets from the consumer unit has gone open circuit. The 230 ? volts above GROUND on the "earths" in the sockets is probably induced votage and not a direct short between the open circuit "Earth" and the Live wire.

 

[adrian.groves]

Yes, we have replaced the bathroom suite an decorated anither room recently.

I have checked for continuity of the ring circuit at the consumer unit and there is no continuity on either the live or neutral so I guess there is a damaged cable somewhere.

 

[PrenticeBoyofDerry]

The problem is when testing continuity end to end readings now, is has this end to end measurement only recently been compromised or has it been like that for sometime?
It sounds very likely that the work withing the bathroom has something to do with this fault.
You need to get in a qualified electrician in to do the required tests and to investigate into where the problem is! But for now I would highly recommend isolating the circuit, locking of the breaker if possible or alternatively removing the conductors from the consumer unit terminals/breaker. So it cannot accidentally be re-energised!

 

[eveares]

The 230 ? volts above GROUND on the "earths" in the sockets is probably induced votage and not a direct short between the open circuit "Earth" and the Live wire.

Clarification: I.e. Capacitive coupling between Line and Earth, like when I had the issue of my oven's chassis not connected to the earth terminal due to two screws not being originally installed.

But for now I would highly recommend isolating the circuit....

2nd That.

 

[bernardgreen]

Capacitive coupling between Line and Earth

Yes, but the voltage induced on the Earth is more likely to be around 115 volt as the earth wire is the centre of the voltage gradient from Live to Neutral in the twin and earth cable.

That doesn't take account of the ratio of Live to Earth and Neutral to Earth capacitive coupling in appliances where the Neutral may not be switched,

 

[John D v2.0]

Your sink doesn't need earthing directly, although the incoming water supply does if metal, although not to protect you from faults inside the property. If it didn't trip the rcbo then it could be from another circuit, or the rcbo is faulty. Sounds like you have at least two serious faults and I can only recommend getting an electrician in to do plenty of testing.
My money is on a damaged cable and earth greater then 1600 ohms/open circuit and probably main bonding missing.

 

[crystal ball]

I have had two similar faults over the years, one was a farmhouse fed by 16mm T&E strung through a tree from the mains in a barn, branch had rubbed through the insulation, live and earth had somehow welded together on the house side whilst the earth on the supply had severed, occupants were getting cracks off the sink & Aga I measured 120v to neutral

Second was a broken neutral on the overhead, most metal in the house was live

 

[JohnW2]

For the benefit of the OP, given all the 'discussion', I think it wise to stress that (unlike many of the 'tingles' questions we get), it sounds as if this could well be a true problem that could genuinely represent a serious risk to life or limb, and that the only sensible course is to leave the relevant circuit(s) switched off and get the assistance of a competent electrician asap.

Kind Regards, John

 

[adrian.groves]

Thanks for all of the comments. As much as I like to do things myself I cannot ignore the advice.

The circuit is switched off and disconnected inside the consumer unit. I shall get an electrician in.

Thanks again.

 

[JohnW2]

Thanks for all of the comments. As much as I like to do things myself I cannot ignore the advice. The circuit is switched off and disconnected inside the consumer unit. I shall get an electrician in. Thanks again.

You're welcome. It would be good if, in due course, you could let us know what the electrician discovers.

Kind Regards, John