1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Live/Neutrals reversed

Discussion in 'Electrics UK' started by Doug99, 24 Sep 2013.

  1. Doug99

    Doug99

    Joined:
    14 Jan 2005
    Messages:
    1,445
    Thanks Received:
    144
    Location:
    Glamorgan
    Country:
    United Kingdom
    I recently had my boiler serviced and the engineer recorded that my input 240v supply live/neutral lines are reversed.

    The boiler is working ok so is there any reason to swap them round?
     
  2. Sponsored Links
  3. RF Lighting

    RF Lighting

    Joined:
    31 Mar 2006
    Messages:
    19,990
    Thanks Received:
    1,354
    Location:
    Leeds
    Country:
    United Kingdom
    Yes!

    If your incommer is reversed polarity, then none of your fuses, or the suppliers fuse will operate on a live to earth fault. This would instead heat your wiring to the melting point of copper, and likely start a fire.

    Also everything in your house is live all the time even when switched off.


    Get the suppliers out NOW

    They will not charge you for this repair.
     
  4. phatboy

    phatboy

    Joined:
    22 Jan 2012
    Messages:
    2,189
    Thanks Received:
    258
    Location:
    Jersey
    Country:
    United Kingdom
    RF, it may be just an FCU for the boiler with reversed wiring, not the whole installation?
     
  5. ericmark

    ericmark

    Joined:
    27 Jan 2008
    Messages:
    18,576
    Thanks Received:
    1,743
    Location:
    Llanfair Caereinion, Nr Welshpool
    Country:
    United Kingdom
    As you may realise where line and neutral are swapped does make a big difference in Europe they use non polarity plugs and sockets banned in the UK and since most stuff has to work either in Europe or UK swapping the lives so line and neutral is reversed will not cause a failure.

    However our earthing arrangements are not the same as rest of Europe so really to ensure safe operations line and neutral do need to be correct.

    Please note neutral is a live wire we call the phase wire in a single phase supply 'line'.
     
  6. securespark

    securespark

    Joined:
    11 Jan 2004
    Messages:
    37,132
    Thanks Received:
    1,288
    Country:
    United Kingdom
    Where did he test from?

    Which company was it?

    Did he raise any paperwork?

    Did he call the DNO?
     
  7. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    48,608
    Thanks Received:
    3,189
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    As phatboy pointed out at the start, it's not clear whether it is the DNO supply that has L/N reversed (in which case they obviously must be informed) or merely the supply to the boiler (or maybe the OP's entire installation, post meter).

    Kind Regards, John
     
  8. Spark123

    Spark123

    Joined:
    2 Jun 2005
    Messages:
    14,841
    Thanks Received:
    474
    Location:
    Cumbria
    Country:
    United Kingdom
    It could be an issue with the earthing, he needs an electrician to come and find the problem.
     
  9. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    48,608
    Thanks Received:
    3,189
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    He certainly needs an electrician, to ascertain what (if anything) is wrong, and to get it remedied if necessary. However, I'm not quite sure how an 'earthing issue' could mainfest itself as an apparent L/N reversal.

    Kind Regards, John
     
  10. Sponsored Links
  11. Spark123

    Spark123

    Joined:
    2 Jun 2005
    Messages:
    14,841
    Thanks Received:
    474
    Location:
    Cumbria
    Country:
    United Kingdom
    It is seen more on TT supplies where there is no effective RCD protection, a L-E fault makes E at the same potential as L and shows up as L-N reversal.

    A disconnected E and downstream L-E fault will show the same too.

    Needless to say, either case needs remedied quickly.
     
    • Thanks Thanks x 1
  12. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    48,608
    Thanks Received:
    3,189
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    Ah, yes - I was thinking only of a single problem/fault/'issue'. If there is an L-E fault and the absence of an adequate earth/protective device combination, then, yes, I can see how it could appear as an L-N reversal. I was trying to think (without success) or how an 'earthing issue', alone, could manifest itself as a L-N reversal.

    If I were a betting man, I think my money would probably be on the boiler man having looked only at what was coming out of an FCU and that mis-wiring of that (rather than of the whole installation, or the supply) is what he identified as a L-N reversal. I would certainly think theatthe first step should be to get an electrician to find out what's going on, rather than (as some have suggested) immediately 'troubling the DNO'.

    Kind Regards, John
     
  13. Astra99

    Astra99

    Joined:
    1 Feb 2011
    Messages:
    902
    Thanks Received:
    144
    Location:
    Gloucestershire
    Country:
    United Kingdom
    Before anyone goes panicking to the DNO, surely the use of a £3.50 plug-in socket tester (NOT a neon screwdriver!!!) will give an better indication of whether the fault is simply a mis-wired FCU or something more serious! If three lights DON'T come on, there IS (potentially) a problem!
     
  14. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    48,608
    Thanks Received:
    3,189
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    As I've just written, I agree that they should try to suss out what's going on before anyone contacts the DNO (who might well not be the ones who can sort it out, anyway. However, if they invested in a socket tester and got 'three greens' when plugged into sockets in the house, there would probably still be a need to get an electrician in to work out what the boiler man was worried about, so, IMO, they might as well get an electrician in to start with. ... and, of course, if the tester showed an apparent L-N reversal which was due to the sort of 'double issues' that Spark123 mentioned (or, indeed, due to the whole installation being 'reversed' at the CU), the DNO would not be the people who could sort it out, anyway - so another reason for getting an electrician first.

    Kind Regards, John
     
  15. Adam_151

    Adam_151

    Joined:
    17 Jun 2004
    Messages:
    6,698
    Thanks Received:
    280
    Country:
    United Kingdom
    Didn't we have one on here a while ago where the fault was on one of the strappers of a two way lighting circuit and it took a while before someone worked out why the polarity appeared to be changing itself at will :LOL:
     
    • Thanks Thanks x 1
  16. efiste2

    efiste2

    Joined:
    14 Apr 2007
    Messages:
    492
    Thanks Received:
    33
    Country:
    United Kingdom
    Cant speak for other DNO's but Scot Power take a reverse polarity service very seriously indeed, I think its a straight dismissal for meter fitters, and older staff have their LV Authorisation removed instantly......
     
  17. Maxatoria

    Maxatoria

    Joined:
    31 Jul 2012
    Messages:
    74
    Thanks Received:
    8
    Country:
    United Kingdom
    When my mum had her cutout changed the first thing they did was check the polarity before even touching the cut out and one of the guys said they went to one house to change a cut out and the polarity test was wrong so they left the house disconnected and told them to find someone to chase down the problem before they'd reconnect them
     
Loading...

Share This Page