Polarity Query

Discussion in 'Tech/Mech General' started by Figaro, Jul 11, 2015.

  1. Figaro

    Figaro Funster

    Joined:
    Feb 22, 2011
    Messages:
    845
    Likes Received:
    678
    Location:
    Newcastle under Lyme Staffordshire
    I wanted to do a small wiring job in my Hymer (2003) 544.
    There is a locker obviously intended for a 14" crt TV no longer used for housing a TV.
    I wanted to replace the 12 volt socket for a twin USB socket for charging phones / tablets etc.
    There are two wires brown and blue, when I put the multi meter on them : -
    Red probe to brown wire and black probe to blue wire the needle went down :(
    When I put red probe to blue wire and black probe to brown wire it registered 12 v.
    I had expected the brown to be live and blue neutral o_O
    Is this telling me blue is live and brown neutral and is this as it should be ? Or maybe I`m missing something.
    TIA
    Chris
     
  2. scotjimland

    scotjimland Funster Life Member

    Joined:
    Jul 25, 2007
    Messages:
    28,934
    Likes Received:
    25,574
    Location:
    .
    Yes , it can be confusing , Hymer use brown as neutral - and blue as positive. +

    I discovered this when I changed the water pump.. I connected it the 'conventional ' way and it wasn't pumping properly.. then checked and found it was wrong polarity..
     
  3. andy63

    andy63 Funster

    Joined:
    Jan 19, 2014
    Messages:
    1,863
    Likes Received:
    6,545
    Location:
    south shields
    yes that's what its saying... the blue is positive.. you are using an analogue type meter if it were a digital you would just get a -12v and + 12v to indicate the polarity.
    ta andy
     
  4. hilldweller

    hilldweller Funster Life Member

    Joined:
    Dec 5, 2008
    Messages:
    26,475
    Likes Received:
    25,170
    Location:
    Macclesfield
    Believe your meter, the Germans use strange colours. I damaged a TV knowing full well the colours were wrong but brain went on autopilot and wired up the TV reversed.
     
    • Like Like x 1
  5. Techno

    Techno Funster Life Member

    Joined:
    Jul 28, 2010
    Messages:
    13,864
    Likes Received:
    14,526
    Location:
    Leeds the one up North
    That's why we won the war :LOL:
     
    • Like Like x 1
  6. John Laidler

    John Laidler Funster

    Joined:
    Jan 9, 2013
    Messages:
    8,587
    Likes Received:
    11,576
    Location:
    Plympton, Devon
    At the risk of muddying the waters, the terms Live and Neutral apply to domestic AC mains supply. For DC supplies the two wires are positive and negative and this is quite different to live and neutral.
     
    • Like Like x 2
  7. Techno

    Techno Funster Life Member

    Joined:
    Jul 28, 2010
    Messages:
    13,864
    Likes Received:
    14,526
    Location:
    Leeds the one up North
    Absolutely correct and I usually pick that up but I'm on holiday still :p
     
    • Like Like x 1
  8. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,484
    Likes Received:
    16,967
    Location:
    YO11 2BD
    NEVER rely on logic where motorhome wiring is concerned.

    I just fitted a volt meter and dual usb socket in my caravan.

    Voltmeter wiring is blue with white stripe = pos 12v....yellow with white stripe is neg 12v

    Usb wiring is plain blue =pos 12v....brown with white stripe = neg 12v.

    On my RV all major wiring is black.....with grey tracer numbers so small you need the Hubble telescope to see them.
     
  9. tonka

    tonka Funster Life Member

    Joined:
    Jul 2, 2008
    Messages:
    5,343
    Likes Received:
    7,604
    Location:
    Cannock, Staffs or Benidorm, spain
    Should try an Autotrail.. From memory I think their negative is orange and white !!
     
  10. Techno

    Techno Funster Life Member

    Joined:
    Jul 28, 2010
    Messages:
    13,864
    Likes Received:
    14,526
    Location:
    Leeds the one up North
    Pre swift Autocruise too but positive I think?. Not really a problem where the colour is nothing to compare with accepted standards but clearly a BLUE positive and a BROWN negative is designed to confuse the enemy if captured :LOL:
    Top marks to the OP Chris for using a meter!
     
    Last edited: Jul 11, 2015
  11. Figaro

    Figaro Funster

    Joined:
    Feb 22, 2011
    Messages:
    845
    Likes Received:
    678
    Location:
    Newcastle under Lyme Staffordshire
    Thanks guys, excellent replies as usual (y)
     
    • Like Like x 1
Loading...

Share This Page