electric shock from water pipes AND live/neutral reversal

[hispania]

My partner has just received an electric shock (which knocked him backwards) when he touched water pipes under the sink (he is replacing the sink and needed to make some adjustments to the pipework).
For some weeks we have experienced warm water for about 15 seconds after turning on the cold tap, and thought it was a problem with the mixer tap but we are still getting warm water from the new, separate cold tap.
Trying to fathom why the water pipes are live he used a ring mains tester in each 3-pin socket in the house and all showed live/neutral reversal. He had tested all sockets a few years ago and all were ok. The only work done on the house since that previous test was 3 years ago when a new gas boiler & pipework were installed.
We still have an old-fashioned fuse-box with re-wireable fuses.
Any suggestions as to the cause of these problems would be much appreciated.

 

[HERTS P&D]

Call out an electrician straight away.

Andy

 

[rjm2k]

The warm water is probably just conduction from pipes close to each other but the electrics are dangerous! You probably have no RCD and it sounds like you have a short to earth. Live neutral reversal means that any lamps with screw in bulbs could be killers if the holder is metal and you touch it!

 

[Adam_151]

As others have said, call an electrician ASAP.

But in the meantime, you might want to try and isolate the faulty circuit. Switch the consumer unit off, pull a fuse then switch it back on, go try the 3 neon socket tester again, do you still get reverse polarity on any sockets that are still on?. Then switch off again, put fuse back in and remove the next one before switching on.

If having one of the fuses out gets rid of the reverse polarity indication, then leave it out until the electrician can look at it.

As others have alluded to it very much sounds like an installation with an ineffective means of earthing (or a TT with no RCD/faulty RCD) and a live to earth fault.

It needs dealing with, a fatal shock or a fire could result (it'll also be increasing your electricity consumption). I'd advise that you avoid baths/showers until the fault is resolved

 

[westie101]

You can get the same effect where there is no earth and there is an unrelated wiring fault.
The installation of a boiler make me suspicious.

Last one we had was no earth and a fault on a lighting circuit! This was reported by an experienced electrician as an incorrect polarity, who was quite amazed with it when we installed an earth and a fuse promptly operated.

So have a look to see if there is an earth that has been disconected

 

[AdrianUK]

I think the problem you have is that there is an earth fault present, your system is using the water pipe as an earth electrode & you have have no RCD.

There will be fault current flowing to earth through that water pipe. Since the earth loop impedance is no low enough, the fault current is not large enough to open a fuse. Once your partner disconnected the water pipe he would have broken the circuit & hence received a shock from the now isolated water pipe.

This scenario would also be mis-identified by the plug-in-type socket testers as live/neutral reversal.

YOU NEED TO GET AN EXPERIENCED ELECTRICIAN PDQ!!!!!

 

[securespark]

One possibility is that you have had a meter change and they have swapped polarity. It is extremely rare, but it does happen.

I came to a house after ENWL swapped a meter out and it was a case of RP.

 

[PrenticeBoyofDerry]

You obviously need an electrician out to sort why you have live pipework and the reasoning behind the reverse polarity issue. Also you will require a plumber, slightly warm water at the cold or any tap is a health issue, legonellia is something that must be addressed!

 

[hispania]

Sorry folks - my partner misunderstood the tester; its actually a neutral fault.

Many thanks for your replies - an electrician has been called.

 

[JohnW2]

... slightly warm water at the cold or any tap is a health issue, legonellia is something that must be addressed!

Whilst what you say is to some extent theoretically true, it is almost a universal phenomenon when (as very commonly) cold and hot water pipes run in close proximity, or even when cold water pipes run alone for significant distances through heated buildings. That's why, to the annoyance of the eco-conscious, most of us often have to 'run the tap until the water gets cold'!

Kind Regards, John

 

[PrenticeBoyofDerry]

it is almost a universal phenomenon when (as very commonly) cold and hot water pipes run in close proximity

which the water regulations deal with, with regards to positioning and pacing, so if they are not compliant then that could be a cause which require dealing with.

or even when cold water pipes run alone for significant distances through heated buildings.

again water regs would cover undue warming

That's why, to the annoyance of the eco-conscious, most of us often have to 'run the tap until the water gets cold'!

Which if because of the design of the installation as per above, could be considered a waste of water, which again would be covered in building and water regulations.

Legonellia would not be prevented by running the tap until cold, because if the water is affected by legonellia, once the tap/valve is opened, the spores become airborne.

 

[rjm2k]

Is the warm water from the kitchen tap or another? If you have a loft tank, you aren't supposed to drink from anything but the kitchen tap which should be mains fed.

 

[JohnW2]

it is almost a universal phenomenon when (as very commonly) cold and hot water pipes run in close proximity...

which the water regulations deal with, with regards to positioning and pacing, so if they are not compliant then that could be a cause which require dealing with. ...

That's why, to the annoyance of the eco-conscious, most of us often have to 'run the tap until the water gets cold'!

Which if because of the design of the installation as per above, could be considered a waste of water, which again would be covered in building and water regulations.

True, but AFAIAA, just as with our Wiring Regulations, there is no requirement to 'deal with' existing installations to bring them in compliance with current water Regulations, is there?

Legonellia would not be prevented by running the tap until cold, because if the water is affected by legonellia, once the tap/valve is opened, the spores become airborne.

I'm no expert, but I would seriously doubt whether there is any significant Legionella risk in the ('constantly flushed') mains-fed cold water pipework of a domestic property. Indeed, even the HSE recognises that that 'running the tap to flush out the warmed water' is necessary, when it advises (in relation to Legionella prevention) that the test should be "After running for two minutes at sentinel taps, the temperature should be below 20 °C."

P.S. I think the formatting of your last post could do with some editing

Kind Regards, John

 

[Newboy]

I'm sorry to take issue with you PrenticeBoyofDerry as most of your posts are accurate and very useful but your comments about Legionella spores becoming airborne when water flows from a tap is just wrong.

Legionella is widely present in the environment and presents a serious risk but only in the right circumstances - i.e. when inhaled as a fine mist/aerosol.

On the basis of your comment I suspect that a massive majority of buildings in the UK would be full of floating legionella spores - showers, taps, toilet cisterns etc. all containing water at ambient temperatures having not run for a few hours etc. Or when people return from holidays and no water has moved in the system for a couple of weeks.

I would never underestimate the risk from pathogens but to scaremonger people into altering their plumbing layouts is very unusual for you - usually one of the voices of reason on this site (compliment!)

 

[JohnW2]

I'm sorry to take issue with you PrenticeBoyofDerry as most of your posts are accurate and very useful but your comments about Legionella spores becoming airborne when water flows from a tap is just wrong. ... On the basis of your comment I suspect that a massive majority of buildings in the UK would be full of floating legionella spores ....

Indeed - but, whilst we're at it, and in the interests of accuracy, I would also point out to both PBoD and yourself that Legionella species are non-spore-forming bacteria - so the "legionella spores" you are both talking about do not actually exist. Transmission to man is by bacteria (not spores) in airborne water droplets.

Kind Regards, John