Voltage in shower waste!

[Tridentsystems]

So is it there constantly or just when waste is full of water ?

 

[purplemaf]

Just when the water is going through the waste. I can watch the voltage reduce as the water disappears

 

[KAS1]

What dangerous voltage levels are we talking about here !!!!!!!!!!!

 

[Richard Burns]

What dangerous voltage levels are we talking about here !!!!!!!!!!!

18V well below the level of detection by touch!

 

[Silly Sausage]

Really difficult to know what's occurring here and advise!







How about fitting a metallic waste trap on these shower basins and bonding them to the shower mixer taps... :ninja::38:

 

[purplemaf]

If that were the case I would never have had the call....I have felt this shock and it can certainly let you know it is there!

 

[purplemaf]

Ive been through the idea of having a metal waste put in. First plumber ive spoken to tells me metal traps dont exist?? I'm also not so happy to conclude with that idea as that doesn't answer the problem of where its coming from.

 

[chcnorris29]

Is the voltage there if the water in the waste is from an external source (bucket of water) or just when it comes from the taps of the installation?

Thanks.

 

[purplemaf]

Fair question. It is literally in the tray/basin with the taps/shower turned off and water draining.

 

[Silly Sausage]

Someone did ask earlier, how exactly did you test for this voltage.
What instrument did you use, where did you test from and to, including multiple locations of both points.
Only asking because it may shed more light on the problem.

I'm also assuming that the shower taps are fed from a remote boiler, i.e., not a local electric shower.

 

[odawire]

the plastic waste must be connected to a metal waste that has the fault on it, if its coming from more than one circuit it could be on a main riser? As said before, I think you are going to have to start exposing the waste pipe. Good luck! cant wait to find out what it is!

 

[Silly Sausage]

Cant wait to find out what it is!

Me too.
He'll be the most unpopular member of the forum if he doesn't reveal the cause when he finds it!

 

[chcnorris29]

Take it that the bath is not conductive (metal bath).

 

[KAS1]

Use an analogue voltage tester

 

[purplemaf]

Ok so we have read this voltage so far using a digital fluke probes, a stienel, a robin test kit. Readings have been taken between water-mixer tap, water-pipework bonding, water-driven stake outside, water-final circuit cpc, water-direct to consumer unit MET. These are not electric showers as posted. Bath is not conductive....

Lol! I too cannot wait to discover the solution!!

 

[purplemaf]

Having lifted the drain today I think it's probably fair to say there are 3 downpipes all running down to the same drain as the drain is 4 way with 3 inlets from the house clearly below where each pipe is. So it seems to me that the wastes of each room (bathroom & 2 en-suites) don't even connect till they reach the ground.

 

[Lucien Nunes]

18V well below the level of detection by touch!

I have spent many happy hours working on marine electrical systems soaked in water / seawater / bilge etc. When thoroughly wet, I can tell whether a 12V DC circuit is energised by putting my finger on it. Grasping a 24V terminal with wet hands while sitting on a steel deck in wet clothing can be quite unpleasant. I would not be surprised if they can feel 18V.

What is important here is that the measurement of voltage, in itself, is not terribly informative because the effective source impedance is clearly quite high and the instrument input impedance will likely have a strong effect on the voltage indicated. What is relevant is that the voltage is not negligible, and that ought to be sufficient to make it traceable.

Have you had a chance to take readings, under the same conditions with water flowing, of the following set of three voltages:
a) External test spike to MET
b) External test spike to energised water stream
c) MET to energised water stream
If the conditions are identical and the spike outside the resistance area of the fault, then it should prove conclusively which point is being elevated above true earth.

Also, do you have an IR value for (suspect lighting circuit L+N) to (running water)?

 

[Rockingit]

If that were the case I would never have had the call....I have felt this shock and it can certainly let you know it is there!

Just a thought.....is this place rural?

 

[Tridentsystems]

Get a camera down the waste. Reckon you will find a screw through the plastic that may have nicked a cable on its way. Wood butchers and wet heads !

 

[purplemaf]

I have spent many happy hours working on marine electrical systems soaked in water / seawater / bilge etc. When thoroughly wet, I can tell whether a 12V DC circuit is energised by putting my finger on it. Grasping a 24V terminal with wet hands while sitting on a steel deck in wet clothing can be quite unpleasant. I would not be surprised if they can feel 18V.

What is important here is that the measurement of voltage, in itself, is not terribly informative because the effective source impedance is clearly quite high and the instrument input impedance will likely have a strong effect on the voltage indicated. What is relevant is that the voltage is not negligible, and that ought to be sufficient to make it traceable.

Have you had a chance to take readings, under the same conditions with water flowing, of the following set of three voltages:
a) External test spike to MET
b) External test spike to energised water stream
c) MET to energised water stream
If the conditions are identical and the spike outside the resistance area of the fault, then it should prove conclusively which point is being elevated above true earth.

Also, do you have an IR value for (suspect lighting circuit L+N) to (running water)?

The above checks have been carried out and as you say they are all the same. Have not done IR to water itself to be honest.....can't say ive ever put a test probe in water before this week lol!