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

Difference between Single and Double pole MCB

Discussion in 'Electrics UK' started by thebigbadpad, 27 Mar 2012.

  1. thebigbadpad

    thebigbadpad

    Joined:
    27 Aug 2011
    Messages:
    18
    Thanks Received:
    0
    Location:
    Lancashire
    Country:
    United Kingdom
    Hello guys
    Just wondering what is the real difference between a single pole MCB and a double pole MCB.
    i dont understand why you would need both live and neutral to trip in a double pole becasue in a single pole if live trips then neutral wont be live anyway.

    Any Help Much Appreciated

    Thanks Guys

    BIGBADPAD
     
  2. Sponsored Links
  3. ricicle

    ricicle

    Joined:
    14 Sep 2006
    Messages:
    6,343
    Thanks Received:
    382
    Location:
    Gloucestershire
    Country:
    United Kingdom
    In a system where none of the outputs from the secondary of a transformer are earthed then both poles need isolation/protection as there will be a PD between either pole and earth.
    Centre tapped secondaries also need DP isolation/protection.
    Using a MCB on an unearthed DC supply will require two pole protection/isolation.
    In an ideal world TT supplies should have DP circuit protection as there can be a PD between N and E. Even other systems would benefit from DP protection/isolation.
     
  4. Taylortwocities

    Taylortwocities

    Joined:
    28 Jul 2006
    Messages:
    20,553
    Thanks Received:
    2,132
    Location:
    Oxfordshire
    Country:
    United Kingdom
    Neutral is considered a live conductor.

    Fully disconnecting a circuit is very necessary in TT installations, for instance where neutral usually nowhere near earth.

    Have a read of the BGB 537.1 for clarification.
     
  5. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page