After some advice: Mild tingle from shower when in use

[JohnW2]

Maybe They wouldn't really need to touch any of the showers - plastic inserts in the pipework could presumably be installed a reasonable distance from the showers. However, I accept that it would be a pretty odd way to address the phenomenon you've been experiencing!

It is! But you and DS have got me thinking

To be honest, I'm not sure how seriously either DS or myself intended our 'suggestions' to be taken! It's certainly true that if you totally isolated (electrically) the showers from any (electrical) connection to the electrical installation, it would not really be possible for anything in the electrical installation to affect the shower in any way - but in some senses it's a (perhaps 'unsatisfactory') cheat, since if there were any problem in the electrical installation (which I doubt), it would still be there. ... a bit like 'papering over cracks', which doesn't change the fact that the cracks are still there!

Kind Regards, John

 

[EFLImpudence]

Maybe They wouldn't really need to touch any of the showers - plastic inserts in the pipework could presumably be installed a reasonable distance from the showers. However, I accept that it would be a pretty odd way to address the phenomenon you've been experiencing!

It is! But you and DS have got me thinking

It may be odd in that it would not be a thing that is done as a matter of course but it is a better solution than protection by electrical means.

However, it would also require the removal of any bonding which was connected downstream of the plastic inserts.

 

[bernardgreen]

It's certainly true that if you totally isolated (electrically) the showers from any (electrical) connection to the electrical installation, it would not really be possible for anything in the electrical installation to affect the shower in any way

If you have water flowing to the shower then total electrical isolation is impossible to achieve as water in a plastic pipe is still conductive unless it is perfectly pure distilled or de-ionised water.

Showers can leak and moist floor boards and joists are conductive so any electrical fixture attatched to an affected joist could provide a source of voltage to the damp joist. Damp plaster around a metal backing box can carry the potential of the back box for a considerable distance across the wall.

In almost all of the above possibilities the impedance of the water or dampness would be too high to allow a fatal amount of current to pass into the person touching it ( whatever the other point of contact was ) but enough to give a tingle and possibly a severe tingle. In a few of the cases of current through dampness the current could be high enough to be fatal.

a bit like 'papering over cracks', which doesn't change the fact that the cracks are still there!

And thus the hazard remains as an unknown quantity.

 

[JohnW2]

If you have water flowing to the shower then total electrical isolation is impossible to achieve as water in a plastic pipe is still conductive unless it is perfectly pure distilled or de-ionised water.

I almost added a caveat, because I just knew that someone would come up with that one! However, the pragmatic point is that, since we know that there are no significant voltages anywhere in the earthing system, it is incredibly unlikely that enough current would flow through water in the plastic pipes to represent any significant hazard (even if tingling persisted).

It is becoming pretty clear that, frustrating as it is, we're probably never going to get any 'answer', and the OP changing his CU would obviously not, in itself, change anything. That being the case, we can probably only talk about measures (RCDs, plastic inserts in pipework etc.) which would provide the OP with some additional 'peace of mind' that, no matter what (if anything) is going on, the risks of any serious shock in the future have been minimised.

Kind Regards, John

 

[EFLImpudence]

If you have water flowing to the shower then total electrical isolation is impossible to achieve as water in a plastic pipe is still conductive unless it is perfectly pure distilled or de-ionised water.

What, then is the method of counteracting this when plastic pipes are used

Showers can leak and moist floor boards and joists are conductive so any electrical fixture attatched to an affected joist could provide a source of voltage to the damp joist. Damp plaster around a metal backing box can carry the potential of the back box for a considerable distance across the wall.

Plastic tray?

In almost all of the above possibilities the impedance of the water or dampness would be too high to allow a fatal amount of current to pass into the person touching it ( whatever the other point of contact was )

Better it is not a bonded/earthed pipe or shower mixer, then.

but enough to give a tingle and possibly a severe tingle. In a few of the cases of current through dampness the current could be high enough to be fatal.

What was the other point of contact in these cases?

 

[JohnW2]

What was the other point of contact in these cases?

I think that's one of the most important points - there pretty clearly wasn't one, given that all we seem to have in the shower tray is a metal collar connected to plastic waste plumbing. That's why I think that the OP's tingles, assuming them to be electrically-related, could only arise through capacitive coupling of his body to earth - the upside of which is that would never result in an even remotely dangerous current flowing.

Even if someone starts talking theoretically about current flowing through water trickling down the wall into a pool in the shower tray, that would be 'in continuity' with the shower and the pool of water, thereby not creating any potential difference.

I fear that some barrels are (understandably) getting scraped to an extent that we would probably not normally consider sensible.

Kind Regards, John

 

[JohnW2]

It may be odd in that it would not be a thing that is done as a matter of course but it is a better solution than protection by electrical means. ... However, it would also require the removal of any bonding which was connected downstream of the plastic inserts.

If we are going to approach this pragmatically (with a view to minimising/eliminating any possible serious risk), without necessarily know the cause of the OP's experiences, I suppose there are two, almost opposite, approaches:

1...As above, attempt to isolate (electrically) the accessible shower metalwork from anything else, particularly other pipework with a path to the house's earthing system.(accepting bernard's point that conduction through water can never be totally eliminated) - and also similarly isolate any other metal around the shower area (I don't think there are any which aren't already 'isolated').

2...Having first made very sure that the building really is an 'equipotential zone' (i.e that all required main bonding is present, and adequate), then make sure that there is an adequately low impedance path from the shower pipework/metalwork (and any other relevant metalwork, although I don't think there is any) to the installation's MET.

Even in the absence of protective devices, either of those approaches should make it impossible for anyone in the shower to experience any dangerous potential difference between any two parts of their body.

Kind Regards, John

 

[TheGovernor]

I'm starting to think it's all in my head!!

 

[JohnW2]

I'm starting to think it's all in my head!!

That I very much doubt - but, as I've said it takes very little in the way of volts to be feelable if your skin is 'broken' or damaged - as I said, it only needs about 50mV (0.05V) across an exposed nerve fibre or nerve ending to 'activate' that nerve, and hence be felt. Have you (or anyone else) ever felt any of these tingles when touching the shower with 'intact' skin?

One also shouldn't forget that, even taking all of the shortcomings of the measuring devices into account, you demonstrated some rather interesting phenomena in your videos. there were clearly some some voltages about, even if they were 'harmless' induced voltages.

Kind Regards, John

 

[ban-all-sheds]

Any news?

 

[TheGovernor]

Nothing of note BAS - still waiting on quotations for the RCBO CU as well...

 

[TheGovernor]

I'm still here, but no further forward with my phantom problem

I have had a couple of quotations back for putting in an RCBO CU:

British Gas have quoted for a:
Fuseboard 10 Way Split Fuse Board RCBO & Main Eart (Not sure what the Main Earth bit is all about?) - £485 as a fixed price.

A local independent guy has quoted me :

Wylex 11 way consumer unit with 8 RCBO's would be £530.00

Or

A Wilts Plus 14 way consumer unit with 8 RCBO's which is on special offer at the moment would be £390.00 including installation.

So actually not much in it?

I'm tempted by the BG quote as it is fixed and I'd obviously have a lot more comeback on BG than an independent, plus he is covering himself by saying anything else he finds is extra, which I can understand, but there's some reassurance form a fixed price quotation.

I guess all of those look in the right ball-park?

 

[ban-all-sheds]

I'm tempted by the BG quote as it is fixed and I'd obviously have a lot more comeback on BG than an independent

Unlikely.

plus he is covering himself by saying anything else he finds is extra, which I can understand, but there's some reassurance form a fixed price quotation.

If he's saying that anything else he finds is extra it's not a fixed price.

 

[TheGovernor]

What I mean BAS was that I'm tempted by the BG fixed price Why do you think there'll be less comeback with BG, usually with big firms you have someone to shout at if things go wrong, which is much more difficult with sole traders...

 

[skenk]

10 Way Split Fuse Board RCBO

is that with 10 RCBO's?

The other two seem to be fixed prices as well. No mention about testing before CU change and/or what happens if a circuit is found to have a fault and (eg) won't sit on an RCD.

I got this email recently regarding a bonding job:

"The man from British Gas said we needed to earth/ put a clamp on our gas meter…….it has to be done by a "p-trained" electrician"

I pointed out that I gave the lack of gas bonding a code 2 on an electrical inspection carried out there in 2011 but clearly British Gas recommendations carry more weight than mine!

Considering we're 100 miles away from where part-P applies and that anyone (competent) can install bonding, I have to wonder i BG know their ar$e from their elbow when it comes to electrics!