Small shock from shower

[who took my fluke?]

Been asked by the local club to check out a fault where by the showers often (not always) give off unpleasant shocks. The building is large and is run off 1 phase taking 90amps full load. Any pointers to help me on my way?? The earth system is PME and the transformer is located 100m away from the club.

 

[andy]

what part of the shower? the case (if metal), main water pipe in (if metal), water coming from shower? check and test all earthing

since its for a commercial premises, i would advise to get a qualified electrician to make sure everything is OK, since you (or someone else) could end up with a fatal shock


i also noticed you said showers, not shower. does this mean there is more than 1 and both give shocks? are the both electric of heated by combi?

 

[Panjandrum]

Possibly way off the point - but could the reported shocks be static? Depends on how plush your club is.
We have problems with the car park gate that some assume is electrically unsafe

 

[Stoday]

A bit difficult to build up static in as wet an area as a shower room.

 

[dw3101]

Id also condem the showers until rectified.. a small shock when wet = dead

 

[who took my fluke?]

All the earth bonding is adequate, i though it could have been due to the pump not making a good earth but the pipes into and from the pump are cross bonded. so is the water and gas and so are the water pipes going intothe shower block. there is a small extractor fan taht is in the shower zone and is fed to a fused spur. there are 5 showers in each changing room and it seems that only a few of them are causing the tingle.

havent had time to measure anything yet but was going to start with a simple voltage test of the neutral to cpc to se if there is any PD.

 

[Panjandrum]

It would be interesting, and possibly useful, to know if there is any pattern to "some showers", and to the timing of "often not always".

 

[mapj1]

When you say the cross-bonding is adequate, have you checked that as well as connecting together it actually does reach Terra Firma, somewhere, and that its not just a bizarre symptom of the PME earth having rotted off at the roots - it might be worth, as a just for a laugh test, stabbing a true earth rod in the mud outside, and checking what potential that is wrt the indoor earth (obviously it should only be a volt or two.) The other possibility is that the shower is earthed, but the people coming from the other part of the building are live - is the shock a sudden nip, dieing to nothing, in which case it is capaciitive (static) charge or is it a 50Hz semi-continuous tingle (in which case suspect the mains).
The other DC one, given that it is probably wet, is rather a long shot, and that would be galvanic (accidental battery) effects, though I'd be v. surprised if people felt this, as the voltage induced by even aluminum and copper, which represent the common extremes of building material, are only a volt or so.
Rememeber though that many people have never had a real shock, and may tend to confuse the symptoms of something else .
I think an interview with a victim is in order, what were they touching, were they dry or wet, what did they feel and where is in order.

 

[ban-all-sheds]

I think close observation whilst the showers are in use is the only answer. Since women have thinner and more sensitive skin than men, you should carry this out in the ladies showers....