earthing fault

[seymoc]

when i am at my sink in the kitchen i am getting a shock but only when i don't have any foot wear on (natural tile floor) i have checked the earthing and everything is cross bonded.
there is a socket and a fused spur for a washing machine. HELP

 

[pipme]

Others will have better ideas .. But is it when you stand in one spot ?
Could there be a floorboard nail through a cable, under the tiles where you normally stand, before the sink ?
I had this, through Vinyl floor covering in a bathroom in 70's, a tingling through fingers when in sink of water .. in this particular case, only when floor covering was damp after being washed .... I had knocked a nail into the vacant hole in creaking floorboard, plumb centre through live conductor ... using the old Stanley rubber handled hammer ... still in the tool box... never felt a thing
Used the old neon screwdriver to find the source....

 

[mapj1]

Being cross-bonded guarantees its all at the same voltage, not necessarily 0V though. If you have a meter, measure between the sink and a 'real earth' (hammer a bit of pipe into the garden for this test - alternatively the metal blade of a spade stuck in with a bucket of water thrown over it will do.)
This temporary earth will be high impedance (perhaps 1000 ohms plus) so expect to be able to measure volts on a digital meter, but maybe not to be able to light test lamps etc.
If there is more than 10V measured, then repeat the test to the main earth (MET) at the fuseboard - if this is not the same voltage then your kitchen wiring earths don't actually make it back to the MET, look for the break.
But if the MET is also a bit live, we need to know if you have PME/TNC or TT main earthing (see for reference at top of forum). If TT, your earth spike has rusted through and should be replaced, while if it is PME or TNS, contact your local DNO (see for reference again.)
hope that gets you started
M.

 

[HDRW]

When I was in New York recently, there was an item on the television news about an area of pavement ("sidewalk") where owners walking dogs reported them yelping and jumping about...

Turns out there was a fault in the electricity cable underground (obviously Phase to Earth), and there was a voltage-gradient across the ground. "Con.Edison are looking into it" !

Cheers,

Howard

 

[pipme]

When I was in New York recently, there was an item on the television news about an area of pavement ("sidewalk") where owners walking dogs reported them yelping and jumping about...

Turns out there was a fault in the electricity cable underground (obviously Phase to Earth), and there was a voltage-gradient across the ground. "Con.Edison are looking into it" !

Cheers,

Howard

Better hang on a while then seymoc

 

[tim00]

mapj1, every now and again one comes across gold dust info. on these forums. Your reply was excellent and to the practical point. thanks, now i know.
pipme, you were lucky given the well publicised case of the MP's unfortunate daughter who lost her life due to a stray fixing. Well spotted.
In a recent article and correspondence in "The Journal of Light Construction" or "Fine Homebuilding" magazine there was a similar report from a New Jersey swimming pool - apparently it was due to a historical fault with the Con. Ed. method of grounding/earthing their main supply and /or local transformer. Guess what, it was cheaper for them to continue their bad practice.

 

[kendor]

Being cross-bonded guarantees its all at the same voltage, not necessarily 0V though. If you have a meter, measure between the sink and a 'real earth' (hammer a bit of pipe into the garden for this test - alternatively the metal blade of a spade stuck in with a bucket of water thrown over it will do.)
This temporary earth will be high impedance (perhaps 1000 ohms plus) so expect to be able to measure volts on a digital meter, but maybe not to be able to light test lamps etc.
If there is more than 10V measured, then repeat the test to the main earth (MET) at the fuseboard - if this is not the same voltage then your kitchen wiring earths don't actually make it back to the MET, look for the break.
But if the MET is also a bit live, we need to know if you have PME/TNC or TT main earthing (see for reference at top of forum). If TT, your earth spike has rusted through and should be replaced, while if it is PME or TNS, contact your local DNO (see for reference again.)
hope that gets you started
M.

this brings up the question that others are saying of their not being a requirement in kitchens to bond if bonding isdone properly and regular preventative tests are carried out then these sorts of problems will occur less.

 

[mapj1]

And if like this, its all bonded together, but not actually at earth potential, hopefully because its bonded to a socket whose CPC doesnt actually make it all the way back to the MET, rather than because of a REC or TT supply fault, is actually far more dangerous than if the sink was not bonded at all.
If it were not X bonded, then all you'd have would be a socket with an OC earth, which is bad, but only a dangerous problem if you plug in a class 1 applience with a live to earth leak, but not as bad as a socket with OC earth plus a floating or live sink, which is what we have now.

That is my argument that incomplete bonding can be worse than none at all, and if its not going to be checked and maintained (and how often do you get all the back PIR certificates in a domestic property?) then none at all is preferable...
Hopefully these tingles are capacitive coupling between a floating CPC and the adjacent live core, rather than full blown connection to live, I will feel some relief when the original poster comes back to tell us what he found..
regards M.

PS
Of course if RCD protection has been fitted, then the danger would be vastly reduced, and in the case of the MP's daughter she would probably still have been with us if an RCD had been fitted, as she would if the dishwasher she was leaning against when she grabbed the live plate rack had not been earthed.
In some ways double insulation plus RCD can be safer than class 1 and earthing everything. It is this argument that leads to metal toasters in the USA not having an earth lead. (if you can touch the elements then its better the case is not earthed, they say, totally contrary to the European way, but a safe method providing you do the same to all appliences - what you dont want is one live one and one earthed one you are going to pick up together..) I don't think the argument is clear cut, but fortunately there are not enough accidents to make it a serious point of concern.