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Discuss Immersion wiring and amp sizes in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. Luke105
    Offline

    Luke105 EF Member

    Location:
    Leicester
    set up for immersion goes like this for me....

    Option 1) 16amp breaker > 2.5mm t&e to 20amp DP isolator > flex from this to immersion.

    But how is this set up.....

    Option 2). 16amp breaker > 2.5mm t&e to 13amp fcu > flex from this to immersion

    Are both fine?
     
  2. telectrix
    Online

    telectrix Scouser and Proud of It Respected Member

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    FCU is a recipe for disaster. 20A D/P switch every time for me.
     
    • Agree Agree x 8
    • Like Like x 1
  3. wirepuller
    Offline

    wirepuller Forum Mentor

    Location:
    south uk
    FCU is fully loaded @230v. 20a DP every time.
     
    • Agree Agree x 2
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    • Optimistic Optimistic x 1
  4. Luke105
    Offline

    Luke105 EF Member

    Location:
    Leicester
    What are the implications of this set up

    16amp breaker > 2.5mm t&e straight to timer > flex from timer to immersion.
    Is this posing a danger other than no local isolation?
     
  5. Strima
    Offline

    Strima Electrician's Arms

    Location:
    St Neots
    If domestic no requirement for local isolation if on its own dedicated circuit.
     
  6. GeorgeCooke
    Offline

    GeorgeCooke Regular EF Member

    Location:
    UK
    You could use 1.5mm t&e with a 16a breaker.
     
  7. Luke105
    Offline

    Luke105 EF Member

    Location:
    Leicester
    It was more to do with amp switchgears and isolation rather than cable size
     
  8. Wilko
    Offline

    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Hi - Local 20A DP switch for immersion isolation is appropriate IMHO as work may be done in the vicinity by someone not familiar with boards etc. I use 2.5mm from the board as it has margin for installation Method 103 worst case.
     
  9. Luke105
    Offline

    Luke105 EF Member

    Location:
    Leicester
    So, good practice but not required.
     
  10. mossep
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    mossep Regular EF Member

    Location:
    Kent
    Not sure that is true, where did you hear that? Im happy to be proved wrong though...
     
  11. mossep
    Offline

    mossep Regular EF Member

    Location:
    Kent
    Although a 13A FCU should be ok, in reality it will probably over heat and the fuse carrier fail over time due to the high load.
     
  12. richy3333
    Offline

    richy3333 Forum Mentor

    What do the manufacturers instructions say? Or is this a theoretical question? Local DP switch for me also. If the voltage fluctuates that fcu will die. Seen it happen so many times. Also the local isolation helps Mr wet pants who’s either too stupid or too lazy to isolate elsewhere!
     
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    • Agree Agree x 1
  13. Luke105
    Offline

    Luke105 EF Member

    Location:
    Leicester
    Would you agree no actual requirement for local isolation
     
  14. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    looking over time the only one fsu that would not fail was the mk bakerlight. not the ones we put in now .
     
  15. davesparks
    Online

    davesparks Forum Mentor

    Location:
    guildford
    Local isolation is safer for anyone else working on the immersion heater in the future and also makes it easier for testing in the future.

    A local isolator which is effectively under the constant supervision of the person doing the work is a safe isolation which doesn't rely on them having a lock off kit which many domestic workpeople don't. Also most circuits are rcd protected these days so the local dp isolation prevents tripping the rcd when N and 3 touch whilst working on the immersion.

    And for testing the DP isolation allows you to test a suspect immersion heater without having to disconnect the neutral somewhere.
     
    • Like Like x 1
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