After some advice: Mild tingle from shower when in use

[Jackrae]

If/when you decide to go for a CU upgrade make sure the electrician fully checks your systems out before he dismantles anything. Unless he does so, any pre-existing faults (which you apparently have) may well cause a major headache once an RCD system is installed.

The whole purpose of equipotential bonding is that there is no voltage gradient within a washroom to cause even the most sensitive of bodies to feel "tingles"

 

[TheGovernor]

If/when you decide to go for a CU upgrade make sure the electrician fully checks your systems out before he dismantles anything. Unless he does so, any pre-existing faults (which you apparently have) may well cause a major headache once an RCD system is installed.

The whole purpose of equipotential bonding is that there is no voltage gradient within a washroom to cause even the most sensitive of bodies to feel "tingles"

Based on my experience so far, there's a probably a whole thread about how to find an electrician who will/can do a full check that is actually worth it's salt, there's so much trial and error involved for us lowly consumers

Anyway, just as we might have though we've run aground, I think I have discovered a repeatable test, that doesn't involve me standing in the shower naked

I'll try to be as clear as possible with the following, having been mildly reassured about my misuse of the neon screwdriver in the posts last night, I decided to take my trusty volt pen into the bathroom with me this morning, expecting it to confirm that there is nothing to see.

I've uploaded some photos below just so you can see what I'm doing and that I'm not being a total fantasist All photos were taken by me, stood outside the shower, but after using it.

1. Before I got in the shower I used the volt-pen - no indication of voltage.

2. Had a shower, tested with the back of my finger were I have some rough/cut skin - could sense the tingle.
Having been in the shower for a few minutes, grabbed my volt-pen - It lit up red.

3. Finished my shower, got dried, stood outside the shower, used volt-pen again - it lit up red.

4. Checked with the family what was switched on (looking for something
unusual compared to the tests the electrician did yesterday.

5. Very little was switched on that wasn't already on yesterday, but systematically switched off one at a time anything that was on (TV, Kettle, Downstairs light, upstairs lights). This had no effect, the volt pen continued to indicate voltage.

6. All appliance lights etc off, volt pen still lighting up.

7. Got my wife to switch off the upstairs light circuit at the CU - volt pen then is NOT lit, showing that there is NO electricity.

8. Upstairs light circuit switched back on - volt pen lights up.

9. After 10 minutes or so of waiting, put the volt pen against the shower, doesn't light up (check it against a live cable to make sure it hadn't broken in the last 10 minutes also).

10. Run the shower - no indication of electricity.

11. Douse the main shower body/mixer with water - Volt pen now indicates electricity.

Sorry about the long post

So, I am back to: There is electricity present, it has something to do with the upstairs lighting circuit and it is ONLY present when the shower is wet, with or without me stood in it.

Pictures:

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• TheGovernor
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Just to prove I'm not nuts!!

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• TheGovernor
• 23 Oct 2014
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[Jackrae]

From what you show, you don't have a "problem" -
you have a potentially SERIOUS problem !!!

I suspect there is the possibility that your lighting circuit earth conductor has been connected to the shower plumbing pipework in the belief that this will act as a bonding feature but neither the shower plumbing nor the lighting CPC are then bonded to the main supply earth point.

Induced voltage from the lighting circuit is then being developed onto the shower plumbing.

 

[TheGovernor]

From what you show, you don't have a "problem" -
you have a potentially SERIOUS problem !!!

I suspect there is the possibility that your lighting circuit earth conductor has been connected to the shower plumbing pipework in the belief that this will act as a bonding feature but neither the shower plumbing nor the lighting CPC are then bonded to the main supply earth point.

Induced voltage from the lighting circuit is then being developed onto the shower plumbing.

Thanks Jackrae - so (if I understand correctly) the fix for the scenario you describe would be to properly earth the lighting circuit to the rest of the house as it were?

I suppose this also might show why the guy yesterday didn't find it, because he was testing against the sockets in the house which are "probably" okay, had he tested the lighting wiring he might've found a different result?

There's a bit of me that is mildly annoyed that I am doing the experts thinking for him diagnostically, if my tests are valid and I'm not introducing any errors, then armed with the same info I gave him I've worked out where the problems lies in general terms...

My plan next is to make sure I can repeat the test reliably, then I might call BG back in, although it is likely that they will go down the "design fault so not covered route" it's worth a try. I guess it's also possible there is a faulty light fitting maybe?

 

[bernardgreen]

When in voltage mode ( touching something metal ) the probe lights up if there is a difference in voltage between the hand holding it and the metal it is touching. It is possible that the pipe is at earth potential and that your body is at a voltage high enought to make the probe light up. This would happen by capacitive coupling between the Live wires in the lighting circuit and your body.

From your description one of the things I would check for is a damp area that has reached an exposed Live wire and thus the damp area is acting as a large capacity plate near near you and thus your body is via this capacitive effect at a voltage high enough to make the probe light when it touches an earthed pipe.


Faults like this are outside the training and knowledge of the average electrician who has been trained and assessed for installations and routine testing.

Did the electrician put an earth rod into the ground to obtain a true ground reference for his testing or did he rely on the "earth" terminal at the meter being at ground potential ?

 

[JohnW2]

So, I am back to: There is electricity present, it has something to do with the upstairs lighting circuit and it is ONLY present when the shower is wet, with or without me stood in it.

That does seem to be the case, and I have to agree with Jackrae that it seems to indicate that something is wrong, potentially seriously wrong - so the search certainly has to go on.

Kind Regards, John

 

[TheGovernor]

When in voltage mode ( touching something metal ) the probe lights up if there is a difference in voltage between the hand holding it and the metal it is touching. It is possible that the pipe is at earth potential and that your body is at a voltage high enought to make the probe light up. This would happen by capacitive coupling between the Live wires in the lighting circuit and your body.

From your description one of the things I would check for is a damp area that has reached an exposed Live wire and thus the damp area is acting as a large capacity plate near near you and thus your body is via this capacitive effect at a voltage high enough to make the probe light when it touches an earthed pipe.

I'll have a look around, are you thinking damp in the loft where the lights are or in the floor..? Or basically anywhere?

Faults like this are outside the training and knowledge of the average electrician who has been trained and assessed for installations and routine testing.

Did the electrician put an earth rod into the ground to obtain a true ground reference for his testing or did he rely on the "earth" terminal at the meter being at ground potential ?

No he didn't. He did some sort of continuity/resistance check with his multi-function-meter, I saw some high Ohms readings over his shoulder at one point. He did those checks by initially looking for the earth wire on the mains water pipework in the kitchen, then clamping that and plugging his meter into the mains...

He was using a plug that had terminal for L/N/E and was swapping various terminal in and out.

Once he'd established the ring main had a good earth to the mains water, presumably he took that to be "true" earth and used that as a reference point when checking the radiators, shower assembly etc upstairs.

At no point did he check the lighting circuit as far as I could tell.

So, I'm a little stumped in terms of where to go, I can obviously call British Gas back out under Homecare, or I can get an independent in, but I'm not inclined to pay them by the hour while they scratch their heads with no prospect of a result in any case... this is the problem for the general public, how can I possibly know whether someone is actually any good, all the certifications on the van in the world don't actually tell me how adept they are at solving things...

 

[JohnW2]

I suspect there is the possibility that your lighting circuit earth conductor has been connected to the shower plumbing pipework in the belief that this will act as a bonding feature but neither the shower plumbing nor the lighting CPC are then bonded to the main supply earth point. ... Induced voltage from the lighting circuit is then being developed onto the shower plumbing.

That certainly seems nearest to a credible explanation that we've seen but, if that is the case, it would seem a bit surprising that neither of the electricians have picked that up.

If your theory is correct, it would almost sound as if nothing is connected to the PME earth. Your theory requires that the lighting circuit isn't. Electricians seem to have established continuity between sockets circuits and plumbing. The plumbing itself (assuming all copper) is probably in electrical continuity with the incoming water supply which should be main bonded. A Zs measurement of the lighting and sockets circuits (and, come to that, any other circuit in the house) might be a starting point to give some insight into all this.

Kind Regards, John

 

[JohnW2]

... He did those checks by initially looking for the earth wire on the mains water pipework in the kitchen, then clamping that and plugging his meter into the mains... He was using a plug that had terminal for L/N/E and was swapping various terminal in and out. ... Once he'd established the ring main had a good earth to the mains water, presumably he took that to be "true" earth and used that as a reference point when checking the radiators, shower assembly etc upstairs.

That could be consistent with what I recently wrote in response to Jackrae's suggestion. It sounds as if he may have established that many of the things which should be connected to earth (pipework, various parts of electrical installation) are, indeed, all satisfactorily connected together but leaving the possibility that the 'missing link' might be that, for some reason, none of them are satisfactorily connected to the DNO-supplied PME earth.

At no point did he check the lighting circuit as far as I could tell.

As I commented before, that seems particularly strange in relation to the electrician who suggested that there could be a'neutral-earth leak' on that circuit. Having mentioned the possibility, one might have expected him to test to see if it were the case!

Kind Regards, John

 

[TheGovernor]

... He did those checks by initially looking for the earth wire on the mains water pipework in the kitchen, then clamping that and plugging his meter into the mains... He was using a plug that had terminal for L/N/E and was swapping various terminal in and out. ... Once he'd established the ring main had a good earth to the mains water, presumably he took that to be "true" earth and used that as a reference point when checking the radiators, shower assembly etc upstairs.

That could be consistent with what I recently wrote in response to Jackrae's suggestion. It sounds as if he may have established that many of the things which should be connected to earth (pipework, various parts of electrical installation) are, indeed, all satisfactorily connected together but leaving the possibility that the 'missing link' might be that, for some reason, none of them are satisfactorily connected to the DNO-supplied PME earth.

At no point did he check the lighting circuit as far as I could tell.

As I commented before, that seems particularly strange in relation to the electrician who suggested that there could be a'neutral-earth leak' on that circuit. Having mentioned the possibility, one might have expected him to test to see if it were the case!

Kind Regards, John

Indeed John, he was a nice bloke, comes highly recommended, but was just talking to me about the issue as opposed to doing any investigation, I presume he wants to charge me for doing that test rather than doing it on the spot so is keeping his powder dry... or he doesn't have the equipment..?

Having got him 'round to do me a quote for the RCBO's I was hoping he might do a test just to get the ball rolling...

If I specifically asked someone to do that test, how much should I expect them to reasonably charge me?

If they had the prospect of being paid to fix it, should I also expect them to charge me to do the initial test?

 

[JohnW2]

If I specifically asked someone to do that test, how much should I expect them to reasonably charge me?

Well, assuming that they came with the right kit, it shouldn't take more than 5 minutes - but, of course, there's no way that the total charge would be only for 5 minutes' labour if they had come specifically to do just that. Anyway, that would not be the right approach - you need someone to come and do all of the appropriate tests (some of which have been mentioned) in order to ascertain what really is going on.

If they had the prospect of being paid to fix it, should I also expect them to charge me to do the initial test?

I think the answer to that has got to be 'it depends'. If (as is not impossible), 'fixing it' involved reconnecting one wire which has become disconnected, taking 30 seconds, then I suppose one could not expect the charge for that to encompass any/all testing that had to be done in order to determine what fixing was required. On t'other hand, if the 'fixing' proved to be a fairly big job, then one might expect the testing to be absorbed into that.

Kind Regards, John

 

[ban-all-sheds]

Once the root problem has been found by someone who knows what they are doing, I would suggest the following:

1) Place another call to Homecare, saying that the problem is still there, and asking for a different electrician to be sent to investigate.

2a) If Homecare #2 finds the fault, complain about the competence of Homecare #1.

2b) If Homecare #2 does not find it, demand a refund of the premiums paid on the grounds that the organisation is clearly unable to deliver the service it has been contracted to do.

 

[TheGovernor]

So I thought I'd try and repeat this morning test and video it, if only to prove I'm not making it up!!

The video below shows what I did, which was a "successful" test in demonstrating it. However, after a few minutes once I'd recorded the video it was getting harder and harder to recreate, so I don't have a fully reliably repeatable test just yet, which is going to make demonstrating it to anyone that much more difficult, because all it needs to do is not do it once and they go back into "you're making it up" mode...

http://youtu.be/21W8bY69vPg

 

[TheGovernor]

. Double post.

 

[JohnW2]

So I thought I'd try and repeat this morning test and video it, if only to prove I'm not making it up!! ... http://youtu.be/21W8bY69vPg[/QUOTE]
OK - we believe you Very weird!

Kind Regards, John