I have just fitted a new stainless sink in my kitchen. When I touch the sink and dishwasher at the same time I get an electrical shock. I am not sure if this is to do with earthing the sink or my dishwasher developing a fault? Any ideas?
Unless there is a fault there should be no potential between the two fittings. There is a fault _somewhere_, and it needs to be found in a hurry.
Your sink _does_ need to be earth bonded, as does all the plumbing in the kitchen.
Andrew
This was a thread a while ago and seem to recall considered opinion was that no bonding of plumbing is required in the kitchen except for the incoming water main.
Dave
I don't have a copy of the regs to hand, but from "16th Explained & Illustrated" Pg 29
I accept there may be other methods to achieve a safe system, but this surely, is the most common by a country mile?
Andrew
Not so. The only requirement is bonding of the incoming main. Bathrooms are a different matter for those parts falling within the prescribed zones.
I 'll go with Stefek on this.
Dave
Thanks for the advice, I will check the dishwasher. But how to I earth the sink?
Dave
Most, if not all, metal sinks have a tab welded to them for the propose of making an earth bonding. You make a green/yellow cable in to a fly lead and bolt one end to the tab provided on the sink. The other end goes to a suitable point with an earth equapotential the same as the rest of the pipework and other electrical systems in the house. Commonly the pipes below the sink will have a earth bonding straps already on them. They may be low down on the pipes near the floor.
Some plastic pipework to the kitchen sink taps don't have earth bonding, so you need to make a earth connection inside the nearest socket outlet or something.
You don't need to earth a sink in a question. Fix the fault causing the leaking and get and RCD in your dist board.
It's by far the most likely problem - or the socket and or wiring supplying it. Even the main earthing for the house. I'd get it checked by a pro if I were you - and urgently.
You've not been following this thread?
If the sink is in someway 'live' you have a serious fault that must be found. If all the pipework in the house is copper, it means that will be live too.
If the sink is a perfect earth, and the dishwasher live, then you're into a death situation. If the sink is insulated from everything else because of plastic pipework, then the fact that it's metal makes no difference - it won't present a path to earth even when full of water.
If you can get hold of a DVM - or even buy one - set it to the 250 volt AC range and measure from the sink to other things that should be earthed like electrical socket screws, kettle body, washing machine body etc.
For guidance, I've just performed this test to remind myself of real world readings. My wiring is about 30 years old, but in good condition. My plumbing (all copper) the same, with a stainless steel sink. All pipework (water, gas, central heating) is bonded to the main earth block beside the main fuses by the closest route, but the sink is *not* separately bonded. The main earth was checked recently, and is fine.
My expensive DVM reads a maximum of 3 mV AC between the sink and any socket screw I could reach. The same to the kettle body and the washing machine. That's 0.003 volts. Same between the sink and gas hob, again stainless steel.
To get an electrical shock I'd guess you'd see at least 40 volts or so. So the margin between 'normal' and fault is vast, and easily seen. And this check would certainly show if it was only the washing machine or a more serious fault.
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On Sun, 02 Jan 2005 12:47:55 GMT, "Stephen Dawson" strung together this:
You don't need one for a dishwasher.
You could start with a socket tester such as
Obviously not.
I would suggest the sink is already at earth potential or the OP would not be getting a shock. Adding a few unnecessary green wires will make no difference or make things worse.
Adam
I connected my test meter between the sink and dishwasher and had a reading of 120v. I checked the other applicances in the kitchen and found them to all have the same reading - I eventually traced this to a faulty socket which I have replaced and all seems ok. Thanks for all help. Dave
Sounds like a broken earth, and the RF suppression in at least one appliance was dumping volts onto the rest after that socket - which probably was at such a low current as not to be lethal. However, the ring should have an earth from both ends - or is it a radial circuit?
I got a similar "tingle" from the washing machine a few years ago, a
3-neon socket tester showed no earth, the problem turned to be a poor connection at the screw terminal of the socket, rather than a lack of earth provided by the ring itself. It looked like water had found it's way into the surface mounted pattress at some point, not too uncommon in a kitchen I suppose.I should have fitted an RCD at that point rather than only gettng round to it last week I suppose.
Several years earlier I got a jolt from a thinwire ethernet LAN where a company had imported their PCs from a European sister company, but instead of replacing the shuko->IEC leads with 3pin->IEC ones had used
3pin->schuko adapters without earth, obviously neither end of the 10base2 had been earthed! We left them to it ...My skin is an effective fault detector, but perhaps not the safest option!
The situation is not as clear cut, if the sink is resin .... or if the pipework is plastic. (mine are)
But in this instance the fact that you are having a shock - means you do have an issue to deal with, it's possible that your dishwaher is the item that is not earthed, and touching the sink completes the circuit.
Rick
It is a radial circuit.
Dave
On 3 Jan 2005 01:09:03 -0800, snipped-for-privacy@virgin.net (Dave A) strung together this:
OK then. I've got a ring.
And a nice ring it is too. :-)
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