Shock from power shower

[duzu]

In my first post I suggested that live current is being conducted through the water and ban-all-sheds seems to concur with me. I don't see any other possibility but I'm open to constructive suggestions.

 

[ban-all-sheds]

Ah yes! Silly me (or is it the inconsistent English language which is silly ? ).

You could always join these loonies: http://www.spellingsociety.org/

 

[JohnW2]

In my first post I suggested that live current is being conducted through the water and ban-all-sheds seems to concur with me.

You did, and he did (albeit pointing out that the conductivity of water is pretty low). However, maybe I should have been more explicit, since you seem to have missed my point ...

... on the assumption that there is some earthed metal pipework, tanks or whatever somewhere in your plumbing system, why do you entertain the possibility that you got a shock due to conduction of electricity (from wherever) through the water, yet don't see how an earth problem, which could result in the 'earth' rising to a high voltage, could also result in electricity being conducted to the shower hose/head through the water?

Kind Regards, John

 

[duzu]

... on the assumption that there is some earthed metal pipework, tanks or whatever somewhere in your plumbing system, why do you entertain the possibility that you got a shock due to conduction of electricity (from wherever) through the water, yet don't see how an earth problem, which could result in the 'earth' rising to a high voltage, could also result in electricity being conducted to the shower hose/head through the water?

Because if that were the case, then rather then getting shocks only through the shower hose and head, we would be getting much stronger ones whenever we directly touch other taps and earthed appliances.

 

[JohnW2]

Because if that were the case, then rather then getting shocks only through the shower hose and head, we would be getting much stronger ones whenever we directly touch other taps and earthed appliances.

Fair enough, but you've changed the argument (you're not a politician, are you? )! I responded to your saying that you couldn't seen how an earth problem could be responsible "because the shower hose contects to a plastic thread", not "because you weren't getting shocks from other parts of the plumbing system".

People are suggesting that you get an electrician in, which I suppose is a good idea, but I'm not totally sure what this electrician would/could do - other than determining/confirming whether or not there is a voltage on the hose, and making sure that the RCD is working satisfactorily.

I forgot to ask before - is most/all of your plumbing system copper (rather than plastic)?

Kind Regards, John

 

[phatboy]

I don't see how the main earth connection would have a bearing on anything; the shower hose and head are not intended to be earthed as the shower hose connects to a plastic thread.

With no earth connection to the house, the TV could have a fault and be leaking a large amount of current to earth. If the pipework is bonded, then this current could be transmitted through the water, to the person showering.

 

[bernardgreen]

For an electric shock there has to be two points of contact and they have to be at different potentials. Birds perching on 11,000 volt cables have two points of contact ( their feet ) but receive no shock as both points are at 11,000 volts, no difference between the feet means no shock.

You could touch two pipes that were both at 230 volts and not feel a shock provided no other point of contact existed.

So there is a potential ( voltage ) difference between the feet in the bath and the hose you are holding for you to feel a shock. The most likely reason is the heater tank in the shower is putting a potential onto the water that is different from the potential of the pipework and it is that potential on the water leaving the shower that is causing the shock you can feel.

EDIT I assumed it was an electrically heated shower. As it is a power shower then the potential on the water is coming from the pump, by capacitive coupling if there is no metal in contact with the water ( plastic chamber and impeller ). It may be the earth to the motor frame has become dis-connected due to vibration.

 

[JohnW2]

For an electric shock there has to be two points of contact and they have to be at different potentials.

Indeed, and that's the other part of the OP's situation which hasn't been explored - i.e. what is his second point of contact, and how does it come to be at a different potential from the water within the peipework (since that is what seems to be being postulated)? ...

So there is a potential ( voltage ) difference between the feet in the bath and the hose you are holding for you to feel a shock. ... As it is a power shower then the potential on the water is coming from the pump, by capacitive coupling if there is no metal in contact with the water ( plastic chamber and impeller ). It may be the earth to the motor frame has become dis-connected due to vibration.

This is why I've asked the OP whether his plumbing installation is primarily copper. If it is, then it is very probable that at least the feed pipe to the pump will be connected, one way or another, to earth. Were that the case, I don't really understand how the water within the pump, and adjacent pipework, could be at a significantly different potential from earth, whether due to a fault or capacitive coupling - the earthed pipework would keep it close to earth potential and if the resultant current was high enough, the RCD would operate.

Kind Regards, John