Voltage in shower waste!

[purplemaf]

Hi All,

I am at my wits end here so here goes...

On Monday I was called to a domestic premises with reported shocks occuring while the client was taking a shower. This was apparently first noticed over 2 weeks ago!

We proceeded to do all the relevant checks on Earth Bonding and various testing including IR on all circuits. Most circuits proved to be fine apart from a high Zs (3.06) on the upstairs ring. All bonding was proved to be sound. Install is a PME with a split board with only 1 RCD. Main incomer has a Zs of 0.26. I moved all circuits over to RCD protection to see if any tripping would occur....to no avail.

Upon further investigation we ran a lead out from the board to provide a means of testing in the shower...what is clear is that a voltage of 6v can be meaured between Earth and the actual water in the shower tray but ONLY WHEN IT IS DRAINING THROUGH THE WASTE! This voltage increases to around 18v at least as load is increased around the house.

Upon FURTHER investigation I have now discovered this to be the case on all 3 showers and all basins upstairs. With the basins I actually filled them up, released the plug then could measure the voltage as the water drained...NOT BEFORE. With the showers I ran the water and turned off then measured the voltage again as the water drained. All showers are hot and cold fed with no local pumps.

I have had every circuit apart and individually connected 1 circuit at a time in the board and found that 4 out of the 6 circuits seemed to bring about the voltage. I have also bizarrely placed a lead between the mixer taps and into the water in the plug hole while running the water. This always removes the voltage.

I am left with the only answer that somehow a voltage is finding its way through the waste water and once someone gives it a path then the shock occurs!!

I have had SSE out today checking everything their end....no problems. Contacted the NICEIC...no advice could be given! I've consulted 2 of my so called guru electricians who are stumped. I am hoping that tomorrows investigation of the external wiring will reveal something but I'm not holding my breath!

Somebody please tell me they have come accross this before!!

 

[Tridentsystems]

Shame purple never let us know. He can't still be fault finding

 

[DPG]

Yeah, come on purple - let us know. You've had loads of good advice. Daz

 

[Rockingit]

Shame purple never let us know. He can't still be fault finding

Last I heard he was wearing a snorkel, in the garden pond, trying to megger the gold fish.....

 

[Tridentsystems]

Very conductive I hear. Does me head in when you get a thread that makes you think and is interesting, that then gets left up in the air

 

[HappyHippyDad]

Is Purple really not going to let us know how it ended? I'd really like to know? Theres been almost 5000 views!! Come on Purple!!

 

[Silly Sausage]

He's gone ultraviolet now, never to be seen again!

 

[Tridentsystems]

Should be barred !! Assuming the waste didn't bite him

 

[jimmymac]

Is it just me or has anybody else got this song stuck in there head? Deep Purple - Smoke on the Water - YouTube

- - - Updated - - -

Purple...water...??? It's all a bit funny for my liking!

 

[Phoenix]

Ooooohhhh Now that's Deep!!!

 

[ArseyDee]

Last I heard he was wearing a snorkel, in the garden pond, trying to megger the gold fish.....

Regrettably it turned out to be a shark. Poor old Purple.

 

[7029 dave]

Last I heard he was wearing a snorkel, in the garden pond, trying to megger the gold fish.....

Hope he's got his rubbers on.

 

[skydog23]

" The purpose of connecting the customer's system to ground is to limit the voltage that may develop if high voltage conductors fall down onto lower-voltage conductors which are usually mounted lower to the ground, or if a failure occurs within a distribution transformer. If all conductive objects are bonded to the same earth grounding system, the risk of electric shock is minimized. However, multiple connections between the utility ground and customer ground can lead to stray voltage problems; customer piping, swimming pools or other equipment may develop objectionable voltages. These problems may be difficult to resolve since they often originate from places other than the customer's premises. "

Just found this on the net,
It may help your quest, although it does say it may be difficult to resolve lol.
I'm keen to hear your findings .
May you get to the source my friend.

 

[Wonderwall]

Poor effort not keeping us informed after all the help given here.

 

[BillyTheSparks]

Poor effort not keeping us informed after all the help given here.

It looks like we're going to have to go to the IET forum to find out...

 

[jimmyjazz]

I've had same with 'tingly taps' post a while ago, finishing with SEB digging hole and repairing joint, the end.......no, after this was called in again as fault returned. Bloody macerator was faulty. Have you got one in the system?