30A Fusible Disconnect Switch w/ Copper Pipe used as fuses

Discussion in 'Electrical Forum discussion & Blog' started by edstevn, Nov 3, 2008.

  1. edstevn

    edstevn New Member

    Messages:
    10
    I found a General Electric 30A/240V single phase fusible disconnect switch that was used as a local service disconnect for a hot water heater. It was fed from a 30A/2P breaker out of a nearby breaker panel. I noticed it had (2) 1/2" pieces of copper pipe installed in place of fuses. I'm sure the National Electric Code book would site this as a code violation. Would they accept dummy fuses ? Do you replace the copper pipe with fuses or replace the switch with a non-fusible type?
  2. jimbo

    jimbo Plumber

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    8,997
    Location:
    San Diego
    I don't know if there is such a thing as a dummy fuse. I think it is called "copper pipe"!!

    You can most likely use a non-fused disconnect, but I don't see how it would ever be legal to bypass what is intended to be a fuse.
  3. hj

    hj Moderator & Master Plumber Staff Member

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    Cave Creek, Arizona
    non fuse

    There have been people here who flatten a copper tube and then put it in the meter socket, after it was pulled for nonpayment of the bill, but I am sure the utility does not consider it a "dummy meter".
  4. Chris75

    Chris75 Electrician

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    608
    Location:
    Litchfield, CT
    Either replace with fuses or dummy fuses, but get rid of the copper pipe.
  5. Thatguy

    Thatguy Homeowner

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    1,459
    Location:
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    The current to melt a piece of pipe like this was figured out on another forum. The connecting wires and everything else will melt before this does. I guess that makes it an "anti-fuse."
  6. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    At least they used copper.

    [​IMG]
  7. Johnny C

    Johnny C Electrician

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    Location:
    Mass. & now Virginia Beach, VA
    30 A fusible disconnect with CU pipe.

    Installing copper pipe in place of proper fuses or fuse blanks is a Code violation of 110-3(B). Use of the disconnect sw with other than a product for which it was tested and listed by the testing laboratory. I will not say I haven't done this in an emergency, but it is a Code violation even though the circuit breaker ahead of the disconnect is rated for the circuit size.
  8. Thatguy

    Thatguy Homeowner

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    1,459
    Location:
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    And if you want to make it into a slow blow fuse, fill the pipe with water before crimping. That way the water has to boil off before the pipe melts.
    All-in-all this is a very versatile circuit element.

    Just kidding.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
    Cave Creek, Arizona
    fuse

    If the tubing is sealed so the water cannot leak out, neither will the steam. So the water will heat to a "superheated" condition, (not steam), until something ruptures and then there will be a 'mini' explosion as the energy is disipated in a matter of microseconds.
  10. jar546

    jar546 In the Trades

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    432
    Location:
    USA
    Violation NEC 2005 reference standard

    110.3(B)
    110.9
    110.10
    210.20(C)
    240.6(A)
    240.10
    240.60(C)
    240.61


    Take your pick. Remove and replace with the proper sized fuses
  11. edstevn

    edstevn New Member

    Messages:
    10
    Thanks for your help!
  12. Thatguy

    Thatguy Homeowner

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    1,459
    Location:
    MD
    So should I lay off all the employees I have already hired to start building these little gems?
    :(
    :p
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