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Topic Title: VOLTAGE IN SHOWER!
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Created On: 23 October 2013 09:47 PM
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 27 October 2013 03:29 PM
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daveparry1

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This probably ties in with your high Zs on the upstairs ring then,

Dave.
 27 October 2013 05:57 PM
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OldSparky

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(Id be getting a different spark. That is useful if op wants it sorting, dont come on defending yourself, you would be better spending time trying to sort it than posting on the plumbers forum. )

now thats not nice!

I really hope now a plumber has caused this problem, so get on and find this fault with pics i hope..
 27 October 2013 06:03 PM
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purplemaf

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Yeah I didn't take kindly to that! Anyway. ...

So I found 25v on metal stud with the upstairs lighting on only. When individually switching circuits on it only appears on this lighting. So have totally isolated circuit and when you switch evefything else back on together 7v comes back. As an experiment I bonded the metal in one shower room. 7v no longer there but remained in another room......
 27 October 2013 06:59 PM
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Zs

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I suspect that is because the damaged bit of cable is passing the fault between circuits. It just has to be found. There are times when the common earth and neutral bars are not our friend. Times like this.

Issue a danger notice purple, and go home. You need to rest.

I am aware that your client is looking in on these forums. Mrs Client, potentially, this is a very dangerous fault and it kills people. It will probably turn out to be an innocent looking burn mark on a piece of cable which appears barely to be scratched. At best it will turn out to be a junction made by an incompetent person and the poor wiring there for everybody to see but I doubt that.

Fault finding can take five minutes and that earns us genius points and fifty quid less tax and overheads. Some faults take days to find and while that is going on the client often begins to question the competence of the electrician. Please don't do that. Whoever your electrician is, he is at work on a Sundayand not charging you ( but I trust that you will be able to come to an agreement on this because he has overheads too). He has posted his queries and has a team of experienced scientists and electricians behind him. He is at the stage of having to pull everything apart and you must let him do just that.

As grotty as it is, you can bathe at the local swimming pool. As much of a hassle as that is, when your electrician shows you what he finds you will understand the value of it.

It isn't a blaming game. This is about making you and your children safe so trust that man and trust his instinct. Please.

Zs
 27 October 2013 07:16 PM
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Rulland

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Shame there isn't a 'like' button on the forum, Nice reply Zs, and my thoughts exactly.

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 27 October 2013 08:35 PM
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Zs

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Thank you Rulland.

Just a thought. Was that stud partition added after the original house was wired? I don't know how they build them but do they screw them to the floor? Tom gunn will know.

Zs

edit speeling

Edited: 27 October 2013 at 09:17 PM by Zs
 27 October 2013 09:03 PM
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purplemaf

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With these places its simply build 2 floors then throw up the studwork so guaranteed they screw it all to to floor.

Appreciate the support all :-)
 27 October 2013 10:19 PM
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OldSparky

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could be as simple as no grommet in the stud where the cable pass through, damaged on installation..

Or a plaster board screw caught the wire..

i was way off in my thoughts by the look of it..
 27 October 2013 10:29 PM
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Legh

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Nice post Zs......

However, I think you're stretching it a bit with " experienced scientists and electricians"..
I'm not to sure the electricians would be happy with that association

and metal stud work a plumber was once killed by grabbing hold of metal studing with a faulted cable running through it while holding onto a water pipe in aloft....

Legh

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 27 October 2013 10:39 PM
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AncientMariner

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Really good post, Zs.

Fault finding, as you say, can take 5 minutes or can take days. Sometimes with no logic at all.

At sea one night I had just closed down a radio-telephone circuit to UK and out of the receiver came what sounded like continuous Morse sidetone (when you send Morse, better equipment arranges to send an audio signal to the receivers loudspeaker so that you can hear what you are sending). I pulled the interconnections out and it remained. Transpired later that at the same time it started a 3-phase motor driving an engine room pump had developed an earth on the 440v system - the radio room was on a 115v 3-phase supply fed from an auto-transformer. Once the earth was cleared, the "sidetone" like sound disappeared! Crazy. A few months later, same ship, the "sidetone" appeared again; could not resist phoning the duty engineer to say he had an earth. "How the Hell do you know that" was his reply. Just like you said, sometime 5 minutes, other times a hard slog...

Cheers!

Clive

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Clive S Carver GCGI IEng MIET
 28 October 2013 04:10 AM
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leckie

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It sounds like a line core has been hit with a screw, or compressed, etc, onto a piece of the building structure. From your description, probably the metal stud work. Bear in mind that the stud work will probably be attached to the building brick walls, pipe work fixings, etc, which may cause cross connections of various impedances. Cpc's from immersion heaters, boilers, etc, are also likely to be connected to pipes, metal work, etc. low IR readings from differing circuits are also likely to muddy the waters as again the results will be shared across the MET.

Go back to JP's earlier post and test installation in the correct sequence and locate and rectify individual problems as you go to reduce the shared faults. Leave the cpc's connected to the MET during the IR tests. If you have a circuit reading low between L and the MET try then testing it with the cpc disconnected between the cpc to L and then the MET to L. It it clears between the cpc to L but is still present between the MET to L this may indicate that the L is touching the building structure via a screws, nails, etc.

When you say you are getting 25V with the lighting circuit connected that would obviously indicate that as a very suspect circuit, so test it as described. The 7V appearing when the other circuits are reconnected would indicate additional faults; measure the voltage as individual circuits are connected and try to diagnose which circuits are the primary suspects.

If you can isolate a known fault to say the lighting circuit with a low IR reading between say the L and the structure, break the circuit down by dividing it up. That is, disconnect the supply to part of the circuit and retest to find the faulty section. When it has been established which section of the wiring is faulty make a decision wether to pull the building apart and find the actual problem, or rewire that section. Whichever is easier, though it would be more satisfying to locate the actual fault(s).

A clamp meter with a milli amp range can also be useful in tracing this type of fault. If you clamp across just the line and neutral cores, any measured current will be going down an earth path.
 28 October 2013 07:53 AM
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SherlockOhms

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...........er.....did I not suggest this early on as I'd come across similar before?

Why didn't I put a fiver on it?.

S.
 31 October 2013 09:18 AM
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GB

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Any chance of an up date??

I like to know the outcome of a mystery!!
 31 October 2013 06:12 PM
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OldSparky

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thinking this my self
 31 October 2013 06:28 PM
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Legh

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Originally posted by: OldSparky

thinking this my self


I assume that you are responding to my last post, in which case: Which bit first or second paragraph ?

The holes through metal studing have always appeared to me as dangerous and the use of a rubber grommet or a piece of pipe insulation seems totally inadequate.

What about someone developing a 20-25mm hand held hole punch / cutter that curls the edges over as it punches through ?

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 31 October 2013 06:42 PM
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OldSparky

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Originally posted by: Legh

Originally posted by: OldSparky



thinking this my self




I assume that you are responding to my last post, in which case: Which bit first or second paragraph ?



The holes through metal studing have always appeared to me as dangerous and the use of a rubber grommet or a piece of pipe insulation seems totally inadequate.



What about someone developing a 20-25mm hand held hole punch / cutter that curls the edges over as it punches through ?



Legh


no thinking about an update
 08 November 2013 07:21 PM
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Zs

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Bump.

Any news Purple?

Zs
 08 November 2013 07:29 PM
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OMS

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I wouldn't hold your breath - some drink deep from the pool of knowledge - others just gargle

OMS

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 10 December 2013 08:40 PM
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OldSparky

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bump

any news on this?
IET » Wiring and the regulations » VOLTAGE IN SHOWER!

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