Voltage in shower waste!

[Tridentsystems]

If a screw had nicked a cable and pierced a plastic waste pipe ( unlikely but possible ) then this could happen. Flow won't necessarily be continuous, may only conduct when enough water is flowing to reach a certain level ? Had a similar thing with a drain pump once on a wet room Eco deck. That problem never revealed itself under normal IR tests. Only when client showered and then not enough to trip RCD Floor had 120 v to E at times and was a screw in the end. So easy to put a £20 camera on a draw tape and have a look before ripping bathroom up. Wish I was local I would give a hand for free as I love faults.

 

[UNG]

Wish I was local I would give a hand for free as I love faults.

Was thinking the same myself

 

[Rockingit]

Another part of this mystery equation is that water isn't THAT brilliant a conductor and relies heavily on whatever contaminates it contains instead. Would be interesting to do an IR between the three traps and see how high a reading is obtained. My guess is it will be off the scale still.

Also, if you chuck a decent lump of copper into one of the traps and bond it back to the MET, does the problem go away in the others or remain?

 

[Marvo]

Water itself isn't generally a great conductor but drains usually have a generous coating of slime which conducts pretty well.

 

[purplemaf]

Ok gents here is todays update. Only had a short while at property so I chose to record some IR readings directly to waste water at one of the showers. Also I have double checked and I do definately have 3 seperate stacks that meet in the ground outside.

The following IR readings were taken with each circuit completely disconnected on 500v - 20mohm. I literally had a lead poked into the waste with he water running.

Live to water
Lights Down - 0.62
Lights Up - Clear
Skts Down - 3.07
Skts Up - 0.63
Smokes - Clear
Cooker - 13.55

Earth to water
Lights Down - 0.45
Lights Up - 0.3
Skts Down - 0.07
Skts Up - 0.07
Smokes - Clear
Cooker - 0.08

Water to Met - 0.07
Water to Neutral Bar - 2.45
Water to Bond - 0.08

 

[chcnorris29]

Even if there was a screw in the pipe as there is no voltage at the drains outside where they connect how would you be getting the voltage to the other pipes at the drains in other rooms.

 

[brman]

I think it worth clarifying the answers to Lucian's questions.

He asked about MET to (an unconnected) external earth spike and you implied in your reply you got a voltage there. If you did then doesn't that point to a installation earthing fault?
Or did I misunderstand the Q&A?

2nd question: you say you have experienced this shock. Is it a continuous buzz or a static like short shock?

Lastly, someone suggested testing with an analog meter. I am assuming this was to check whether the voltage held up under a lower impedence load. Did you try that? If you don't have a old meter then maybe something like 100k resistor in parallel with your test leads?

 

[DNS1]

I've not got time to read the whole thread, but this raises an interesting question...

Bonding of incoming gas and water pipes is one of the first things we look for, so why not bonding of waste pipes? I know most are plastic these days, but not all...

 

[Silly Sausage]

I've not got time to read the whole thread, but this raises an interesting question...

Bonding of incoming gas and water pipes is one of the first things we look for, so why not bonding of waste pipes? I know most are plastic these days, but not all...

If they are metal, you would.

 

[Richard]

You say that it is a PME system, are you completly confident that you are getting true neutral? My only thought was that if you had a poor/dropped neutral (externally), possibly you are still getting a good loop impeadance through nearby propertys via waterpipe work, ect?

I think you said DNO had already been so I'm guessing this has already been proven.