5

Yesterday when I took a shower, I got a pretty bad jolt of electricity in my arm when I was done showering, and was about to switch off the water faucet.

I immediately jumped out of the shower, grabbed a flashlight and shut off the main fuse. Grabbed a piece of insulated pliers, and managed to close the faucet without another shock.


The day after, I got a hold of the landlord to tell him about this issue. I borrowed a multimeter from him to check the faucet again today. I connected the ground cable of the multimeter to a ground pin in an outlet, and probed the faucet: And sure enough, it's live! However, the voltage is not constant. It seems to oscillate between 100mV and 82V, in a sort of random phase-pattern.

Next, I tried to disconnect the fuse for the water heater and probed again. It's still live and nothing different. So I then tried to disconnect the fuse for the bathroom as well: And it's still live! (I didn't try with main fuse off, sorry, The landlord had to run and I had to return the multimeter before I could finish)


So here is my question: What could this be? Is there a bad ground connection somewhere, or a leak somewhere to a neutral connection in the pipes? Why is there still voltage on it despite the fuse being shut off?

I live in Norway, So the mains voltage is around 230-240V @50Hz. The house is roughly 30 years old, and the electricity and plumbing system appears to be well maintained.


I am somewhat familiar with electricity and how it works, however, I am no professional. So I won't try to diagnose this issue too deeply unless the clues I give here tell some of you something that could be obvious and potentially easy to fix.


I was shocked so badly I had to go to the emergency room an hour later because I still felt pain in my arm. I was released roughly an hour later, with no diagnosis. My arm is fine today.

I am showering at my mother's house until the problem is rectified.


Update:

The landlord just called me and informed me that an electrician will come tomorrow to look at this problem. I will post an answer with the update on what caused this as soon as I know.

migrated from electronics.stackexchange.com Oct 4 '17 at 20:28

This question came from our site for electronics and electrical engineering professionals, students, and enthusiasts.

  • Sounds deadly. Turn off the power and call/wait for an electrician. – Trevor_G Oct 4 '17 at 19:41
  • 1
    @Trevor That's exactly what I did! Never using that again until I know for sure it's safe. But the nerd in me makes me curious. – Alexander Johansen Oct 4 '17 at 19:45
  • 1
    That's strange enough. Usually the pipes are used for grounding. But these days plumbers are making their lives easier by putting PVC pipes instead of copper, so the grounding is off.. There could be some wire in the wall contacting with the piplines, or some malicious neighbor is willing to kill you. Yet it is strange no fuse is jumping. – Eugene Sh. Oct 4 '17 at 19:47
  • Ya issue is if there is a ground short somewhere you may find something else live.... like the washing machine el. al. – Trevor_G Oct 4 '17 at 19:47
  • 1
    If you live in an apartment complex and the pipes are metallic all the way to the neighbours, the fault may come from one of the neighbors, so even if you cut the mains breaker in your appartment, you might not be safe. Don't touch any faucet (including kitchen, etc) before the electrician has a look at it... – peufeu Oct 4 '17 at 22:41
4

I will bet that your equipotential bond on the water pipes has degraded or even fallen off. I'm in Australia so things may be a little different in Norway, but typically the earth terminals in your outlets will be wired directly to the earth stake (the main earth of the installation).

If you have metallic water pipes (which I'm guessing you do based on the issue you have) they need to have an equipotential bond to make the pipes the same potential (the same voltage) as the main earth point.

If there is no bond then circulating currents in the earth can cause voltages to develop in your water pipes. These currents can come from overhead powerlines or the neighbours house.

The reason for the alternating between 100mV and 82V would be that the source of the current is not operating 100% of the time.

You've done the right thing by changing where you shower until the issue is rectified. Electricity is not something to gamble with.

2

I forgot to update this after the electrician visited and I'm terribly sorry, so here is what happened:

The fault was caused by a neighbor two houses down the street. He had wired a ground and a neutral wire together in an outlet that he installed himself. Causing voltage to leak over the ground wire.

It is illegal to wire outlets yourself in Norway if you're not a certified electrician (and probably a lot of other places as well). The electrician said I was lucky to escape without any injury or complications. The person who did that wiring was clearly not an electrician, and was fined accordingly.

Apparently I wasn't the only person who had noticed the problem. Another neighbor in the neighborhood had also complained.

  • 1
    It seems only fair that you get the money from the fine. :-) Hopefully the neighbor was informed that his actions almost electrocuted someone. That might discourage future "repairs" more than a fine. – fixer1234 Nov 7 '18 at 9:33
  • Do you know, by any chance, how he found that out? – glglgl Nov 7 '18 at 15:34
  • @glglgl Unfortunately I don't know how they did manage to trace it. Since they had received similar complaints from the same neighborhood, they sent out a team of city electricians to diagnose the issue. If I were to guess: They probably have all the fancy toys and instruments to detect issues like these. – Alexander Johansen Nov 7 '18 at 16:16
1

As others have mentioned the fault could be coming from an appliance in your unit or another. We talk about boot leg grounds regularly on this site where some one tied the neutral and ground together in an outlet thinking that would be ok or an old 3wire oven. All the faucets in your apartment may have the same problem but water breaks down your skin resistance so you get shocked at lower voltage levels, you may not feel a shock when wearing socks because the cloth insulates you from ground. I remember getting shocked from the toaster as a kid when barefoot at my grandmother's home, she pulled the plug and turned it over it was old non polarized 2 wire outlets but with socks on I did not get shocked I experimented quite a bit with this and may have been the thing that got me interested in elecricity. So it could be several things a bad connection to earth ground as someone else said but then I would expect more people to experiance to be getting shocked in the building. It could be a heating element in the water heater but pipes are usually bonded to ground. If a boot leg ground or appliance it may be difficult to find unless each breaker is turned off until the voltage is gone then track down that circuit for the items connected until the fault is found.
Added I did think of another issue I have seen in the last few years in one are all the water mains were changed from metallic to plastic, during this upgrade several home supplys from the meter to the home also were changed, when these homes were built that was the only grounding method so now those homes had no ground initially I did 2 homes driving 2 rods and connecting to there main panel, later I dropped flyers offering to update the houses as I had to the 2 , I think I had 20+ home owners have the upgrade. How many more homes out there have this same potential hazard because of plumbing changes?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.