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  1. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    Hi

    I have a old MEM 3 phase Fuse box that has 20A double ceramic fuses per phase ,the question is if I link the 2 x 20A fuses together would I be able to get a 35A feed from it ! , sorry if the answer sounds obvious .

    What is the equation for that ! .

    Spike
     
  2. Murdoch
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    Murdoch Electrician's Arms

    Location:
    Woking
    In one word no.

    Why do you need a 35a bracker?
     
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  3. Pete999
    Online

    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    Why do you want to use such an ancient bit of kit?
     
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  4. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Maybe !
    But it is not considered good practice !
    Tell what your considering ?
     
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  5. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    Thanks for your replies , this 3 phase fuse box is fed from a 16mm2 swa cable and the same size feeds out via one of each of the 20A fuses to a 32A fused breaker about 10 Meter away.

    I am wanting to feed from the 32A breaker into a 63A RCB with 1x 32A mcb and a 16A mcb and a 6A mcb to feed some double sockets and a Welding machine ! , each of other 20A fuses in the fuse box are not used ! .

    Not sure why a 32A fused breaker is fed from a 20A fuse box !.

    PS: none of this is comes into part "P" .

    cheers

    spike
     
  6. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    Because I don't have the funds to replace it ,have tried to find a way of upgrading it using the same box but not found anything suitable ! .
     
  7. westward10
    Online

    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Are you talking of putting two 20A elements across one carrier.
     
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  8. Rob
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    Rob Trusted Advisor

    Location:
    North west
    In a word no.

    Two fuses supplying one circuit is a no no.

    Doubling up a fuse in a carrier is a no no unless it's designed for that, the only place I've seen it done is with semi conductor fuses feeding a VSD. An they are purpose made 'doubled up' fuses.
     
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  9. Lucien Nunes
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    Lucien Nunes Mercury Arc Rectifier Trusted Advisor

    Location:
    London
    In another word - negative. You should not put heavier wire or two wires in one carrier as the contacts of the carrier are only rated for the current stated and may overheat badly with the extra load. Nor may you connect two carriers together each with wire to their maximum rating, as two thermally separate fuse elements do not behave like one element of double the rating, and there is a massive latent hazard of the circuit not being correctly isolated.

    I have seen this done once, I got a belt from it and it eventually burnt out. Please don't repeat this yourself.
     
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  10. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    OK Guys to put this to bed going to replace the DB .

    Cheers Spike
     
  11. Worcester
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    Worcester Trusted Advisor

    Location:
    Worcestershire
    You'll probably need a Type C MCB for the welder circuit, and then bear in mind the reduced Zs for Type C's
     
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  12. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    Yes cheers for that .
     
  13. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    How much load is on the 32amcb ?
    You may be able to put it on one 20a fuse
    And the other 2 x mcbs on the other ?
    It all depends on how heavily they are loaded ?
     
  14. Spike1947
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    Spike1947 EF Member

    Location:
    North yorkshire
    Hi
    Thanks for your reply , could do that but I need them to be fed from a RCD ,would have to use 2x RCB's that way , I am trying to think of a way to upgrade the original box with a heavier 3 phase fuse carrier ! , that is not going to be quite expensive .
     
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