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Live, Neutral and Earth


Quillan
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This could be one for Chancer?

I understand that France does not use PME earthing i.e. neutral is not 'tied' to earth so how, with a meter, can you find which wire is live and which is neutral? Could you work this out by measuring live and neutral against earth and what sort of voltage would you expect to see on neutral? Can you keep it 'basic' please.

PS. We are talking single phase.

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I think that the neutral is tied to earth but at the transformer, each dwelling then has its own earth piquet.

You can use a neon screwdriver to see which one is live, or one of those buzzing voltage detectors or a wet finger [:-))] please dont do that but I used to do so with a quick swipe of a dry finger, trouble was I was so tense I would imagine a shock that wasnt there.

With a multimeter you will get 240vac between a phase and earth and only a few millivolts between neutral and earth, important, this is only true if you have a correctly functioning earth system at the dwelling.

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Thank you, it is rather what I expected but I am no expert. I have to fit a device for the heating system which basically is a wireless receiver device that turns power on and off and it is important that the device is wired correctly for live and neutral.
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Pretty much all devices from a functional rather than safety point of view are not polarity conscious, indeed with French sockets its 50/50 what you end up with, perhaps with CPL devices they use the ground as a screen or something.

I take it your wiring colours are non conforming?

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[quote user="Chancer"]

I take it your wiring colours are non conforming?

[/quote]

Well they should do but when ever I have seen one of these junction boxes opened around the house they have just about every coloured wire you could think of. My thinking is to check, check and check again just to be on the safe side. It's France, you know what its like.

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I hate French wiring. In UK I rarely saw any of the horrors I come accross quite regularly here.

On next weeks job list is to find why a clients fuse box has

water pouring out of it when it rains. Obviously rainwater is getting

through a gaine somewhere. All the junction boxes I have opened in this

place while trying to trace other problems have contained multiples of

every single colour of wire available all so tightly packed I usually

have to use a mallet to get the lids back on.

In my current house, Ze Germans who lived here before and who were responsible for the....errr....."re-wiring" -

[img]http://s7.postimg.org/6whzfalaj/DSCF0012.jpg[/img]

- left it looking like this. Apparently finished. Note no earth connection and all the red wiring up to the old fuses by the ceiling was still all live.

They had also somehow managed to get the live to switch to earth when they wired up a pair of switches in the pantry for a single lamp. I found this out the exciting way when fumbling for the kitchen light switch in the dark....

[img]http://s17.postimg.org/gl5ckzan3/IMG_20150213_174809.jpg[/img]

The last house had the main fuse box directly above the bath. At least I wouldnt have to get out the shower to re-set it if anything tripped out!

Not specifically an electrical problem but typical of the attitudes in a place I looked at a while back....

[img]http://s24.postimg.org/n77lxo5dh/fire.jpg[/img]

"Yeah, its been on fire, but it still works ok"

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[quote user="crakpot"]Hi Quillan I am just down the road from you, Campagne all my 4 input wires are tar black and no identifiable earth so I created my own about 60 Euros and a bit of digging did it[/quote]

My problem is not with the earth but with the live and neutral, I need to know which one is which. I have colour coded wires and it is obvious which is earth and probably neutral and live but because in France you can wire things any way round with reference to live and neutral I need to check. I suspected that measuring against earth would tell me but I just wanted to double check with people who know more than me as I am not a professional electrician. Thanks anyway for the suggestion.

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[quote user="crakpot"]Hi Quillan I am just down the road from you, Campagne all my 4 input wires are tar black and no identifiable earth so I created my own about 60 Euros and a bit of digging did it[/quote]

That is standard across France, it is a triphasé supply, just as well that you didnt wrongly identify one as the earth as they are the 3 phase wires and the neutral, the power distribution companies do not supply and earth to properties, it is done by a seperate earth piquet or buried coil.

How did you test your earth impedance? Have you respected the normes, they are very important in respect of earthing, have you fitted the correct barrete de sectionnement for testing purposes? Do you have an LEP and an LES?

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I, like T and Chancer use a Neon Test, to carry out a primary check.

Having the benefit of a large decent analogue meter, I also test the AC voltage potential between:

Live and Neutral:

Live and Earth:

Earth and Neutral.

Any stray voltage between Neutral and Earth should be very small; circa 1-2 Volts AC.

However, experience in France has taught me with older houses, it often is much more!

A good chum, for example, had a four branch metal light fitting in the salon, which provided a delightful "Fizz" if one touched it!

[:'(]

Normally, this is caused by tired and crazed surface of insulation in junction boxes, switches or the fitting itself.

I had a similar fault with one of our houses in the UK, years back: from the 30 Amp electric cooker double pole switch, with a 13 Amp socket, to which  Mrs Gluey had connected the old, metal cases microwave.

I put this down to the idiot siting of the outlet: immediately above the cooker, thus loads of heat and moisture had degraded the urea formaldehyde moulding. As it would.

If one is completely self-wiring a house, it does pay to invest in a low-end insulation tester.

E.G.

Since the manufacturing and type approval standards are now much more rigid on insulation of all mains components and since time ages any form of plastic, as a matter of safety, I never ever re-use old mains wiring kit. False economy.

Whilst the plug top testers (e.g. Martingale) are a reasonable assurance, of course, these don't fit other terminal equipment. Not sure in any case if they are available for French etc sockets??

A Megger insulation tester, now, I note runs into two or three thousand pounds: megger kit and megger price!

PAT routines, of course (offices, workshops, rented accommodation) cover insulation as a core part of certification.

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Hi in reply to Chancer

I am no electrician just relying on a 1968 OND in applied science, as there no earth I used the barrette, a metre and a half picket, and 15 metres of bare copper cable a metre deep its better than nothing and worked on my last 2 properties both which subsequently pass the tests when sold
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I too have no means of measuring so I write a suitable number on the Consuel form and let them test it on the day, I would be uncomfortable without it being tested but it has made me realise that I am in exactly that situation in the UK on my pied à terre so I am taking my RCD tester back with me to at least check with that.

Soil conditions vary so much and thats what would concern me, the earth piquet for my flat was in an outside shed with a dirt floor, plenty of damp and it gave a reasonable figure, when I did the one for the colonne collectif it ended up being right in the centre of a 90 year old building into very dry chalk yet the reading according to the Consuel man was much lower, very good indeed [8-)]

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As soils go its one of the better conductors but my (effectively) outside piquet in damp soil whilst Under the 100 ohms was not by a long chalk (pun not intended) I expected the one in the middle of the building to be far worse as it was very dry soil that has seen no moisture for 90 years yet when he measured it it was very low, 20 ohms IIRC, its not noted on the attetstation only the 60 ohms that I guessed at, I have just looked at my first one for the "outside" piquet and it was measured at 49 ohms.

A question regarding RCD testing, when you use the test button on the RCD it creates a differential imbalance between phase and neutre, it cannot bleed the current to earth as an RCD has no earth connection so I guess it goes to the incoming neutral upstream of the sensing coil, what about the plug in RCD testers like this: http://www.gotronic.fr/ori-testeur-de-prises-vt35-7803.jpg I know in the past the RCD test function would not work when the polarity was reversed, a 50/50 chance with French wiring but I'm not sure if the test current goes to earth or not, logically I think it must do. I want to use this for testing the efficacity of the earth connection of my pied a terre (pun again unintended) in the UK which I did with an earth spike, its fed from a sub meter on the main house and I didnt want to rely on the screen of the SWA for earthing in case someone disconnected it.

I know that I wont be able to measure whether the RCD trips in 30 milliseconds but if using the tester it does trip can I be sure that the current has been passed by my earth spike?

Next unknown is whether my UK to French socket adaptors reverse the polarity like the French to UK ones do, that would screw up my tester.

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To check out the U.K. to French adaptors can't you just meter them through??

As far as standards are concerned? Our house was built in 1982 by a master builder for his son who was a high up in the local housing group and is done to a very high standard The standard used for the wiring is also very good, if a bit confusing  [8-)][8-)][:-))]

[URL=http://s47.photobucket.com/user/Jonzjob/media/Johns/Jar-a-worms.jpg.html][IMG]http://i47.photobucket.com/albums/f180/Jonzjob/Johns/Jar-a-worms.jpg[/IMG][/URL]

That's one of the many conection boxes througout the house. I have had a lok at a couple and very quickly put the lid back on again [:-))]

Just reciently I had to change a neighbours electric radiator. Not a cheap one either. When I came to wire it into the wall I found that it came with a black, blue and very dark brown wire! The black was the earth wire!! NF stamped an all!!! Still, this is France init.

As has been mentioned a couple of times, the easiest way to find out which one is line is with a neon mains tester. It only lights up when it hits a line wire..

Edit :  - I forgot to mention that the clear thing in the photo is the relay for the 4 way switching in our kitchen/diner..

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