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31-10-2010, 18:27   #1
jamesekeenan
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Live Neutral reverse?

I was working in a friends house yesterday and when I tested the sockets with my socket tester it was beeping indicating live neutral reverse.

It is a very old house and alot of work has been done on it over the years. He told me that has been no electrical problems in the house so I walked away happily.

Can anyone explain what exactly are the consequences of this and how it happen?
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31-10-2010, 18:53   #2
meercat
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i wouldnt be too happy
among other problems anything connected to socket(appliances lamps )will be switching the neutral and may have a constant permanent live at the bayonet cap
did you check the consumer unit/fuse box to see where reverse polarity is happening
if it is at consumer unit/fuse box then neutral is protected by fuse/tripswitch and if this blows it does not interrupt the live to socket outlet
have you checked lights cooker immersion
dont leave as it is
get a competent sparks to check it out and FIX it
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31-10-2010, 19:15   #3
Bruthal
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Reverse polarity wont show up in the operation of any electrical items in a house. They will all work as normal, but this does not mean its ok.

Did you only check one socket?
Check fusebox as meercat says to see if its just a single socket or socket circuit thats reversed, or is it at the feed into the board. It could be just that one socket.

Another problem with reverse polarity at a socket is that if there is a Neutral-Earth short or fault in an appliance, this in now a Live-Earth fault except there is now no plug fuse in the fault path, and if the neutral earth is reversed feeding the fuse box then there is no fuse at all before the esb one.

Needs the sparky alright.
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31-10-2010, 20:51   #4
M cebee
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prob the 'final circuit' is reverse polarity then

or could be part of the circuit


some sockets are DP so switching off may isolate
but the L-E fault backs up to the next protective device wired correctly
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31-10-2010, 23:56   #5
ntpm
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I have been called to new installations (which were tested and certified).which have had some sockets incorrectly wired.
The cabling was correct from the consumer unit but possibly the apprentice was left to make final connections to socket terminals and managed to get live and neutral mixed up.

Quick check is to turn power off open up socket and visually check terminal labeling and colour of cables.

And if you have a multimeter, switch power back on to actually check the cables for voltage for and polarity.
L to E = 230v
L to N - 230v
N to E - 0v ( but could go upto 30v ish still ok)

Also recently went to a house where the original lights cabling was red (live) and black (neutral) and extra lights were added BUT with new brown (neutral) and blue( live) cabling..
An innocent mistake or didn/t check polarity after connection either way lights will work but not safe.

Last edited by ntpm; 31-10-2010 at 23:58.
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01-11-2010, 00:32   #6
RoundyMooney
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I'd be very wary of walking away from something like that, if I was working there in an electrical capacity (I assume you weren't, OP!).

He needs the whole installation checked out by a competent person asap!
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01-11-2010, 01:35   #7
Electricman999
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I agree you better get the entire electrical installation checked out by a component time served electrician before somebody gets electrocuted or the place burns down.

Make sure they are RECI Or ECSSA registered & carry insurance
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01-11-2010, 06:46   #8
pieface_ie
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As already said its not a good idea to walk away from something knowing its not operating as should, do in a domestic installation a L N reverse appliances will still "function" as normal but not ideally safe.

It would be easy enough to recify, do time consuming, but definatley do not leave it.

Last edited by pieface_ie; 01-11-2010 at 06:47. Reason: early mornings!
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01-11-2010, 10:52   #9
Bruthal
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Quote:
Originally Posted by ntpm View Post
I have been called to new installations (which were tested and certified).which have had some sockets incorrectly wired.
The cabling was correct from the consumer unit but possibly the apprentice was left to make final connections to socket terminals and managed to get live and neutral mixed up.
I never laugh at mistakes like that in final connections, anyone could do it, its easy to get distracted etc even though most might say `not me`.

A new installation with socket wrong should be found if properly tested, it only takes a few minutes to do socket polarity tests. But again, mistakes are made in every aspect of everything, testing included id say. As i said before, an installation thats certified does not mean its done to a good standard either. But it still has to be done to give some sort of standard.
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01-11-2010, 10:56   #10
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Quote:
Originally Posted by pieface_ie View Post
As already said its not a good idea to walk away from something knowing its not operating as should, do in a domestic installation a L N reverse appliances will still "function" as normal but not ideally safe.

It would be easy enough to recify, do time consuming, but definatley do not leave it.
O` no not the text spelling
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01-11-2010, 14:08   #11
M cebee
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every socket should be checked with loop-impedance tester after energizing installation imo

that's the way i do it anyhow

i have more faith in live testing than dead tests
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01-11-2010, 14:11   #12
Bruthal
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Yes cant argue with that. The more points tested the more reliable the results.
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01-11-2010, 14:15   #13
M cebee
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i see reverse-polarity all the time when working on jobs


it may be unrelated to the job you're doing -and customer may not want to fix it

but i always make them aware anyhow
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01-11-2010, 22:18   #14
ntpm
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Quote:
Originally Posted by M cebee View Post
every socket should be checked with loop-impedance tester after energizing installation imo

that's the way i do it anyhow

i have more faith in live testing than dead tests

Loop impedence test, if carried out properly will also show the integrity of ring circuits and earths in radial circuits.... I know many guys who " carry out test" that don't know how to properly evaluate the readings.
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01-11-2010, 22:31   #15
M cebee
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your Zl must be within the limit specified for the mcb or fuse and type of circuit


how will it verify the ring circuit?


you might have parallel fault paths when testing Zl at sockets so it can't always veriify the cpc
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