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Backfeeding with a portable generator - REAL safety concerns???

Discussion in 'Electrical Engineering' started by Friday, Sep 6, 2004.

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  1. Guest

  2. Jim Michaels

    Jim Michaels Guest

    Many UL listed transfer switches use off the shelf household circuit
    breakers as their isolation elements (they do add a mechanical

    This would seem to negate the failed main breaker argument.

    A lockout padlock on the main breaker would go a long way toward
    removing danger.

    In almost every case a back feed situation would result in an
    immediate generator failure (engine stalling or circuit breaker
    opening) due to loads in neighbor's homes. The exceptions would be
    very large generators or a very small isolated line section (no

    This all leaves the mistakes happen even to careful people issue.
    And in this case a mistake could lead to manslaughter charges.

    Bottom line: Use extension cords or intall an approved transfer
    switch of some sort.
    Remove SPAMX from email address
  3. John Gilmer

    John Gilmer Guest

    Well, "built in" microwave ovens usually plug into a 15 amp outlet. (It's
    supposed to be a single circuit and all that but ....)

    Likewise, in some places, dishwashers are plugged in. In many places,
    garbage disposals are pluged in. Likewise, window Air Conditioners are
    plugged in.

    And in all these cases, there ain't a "twist lock" in sight.

    So maybe things are "achanging."
  4. Guest

    A breaker is a single throw device. It cannot transfer a circuit. It
    would be interesting to see the switches you have in mind to get
    an idea of how they accomplish a positive transfer. Do you have
    a particular make/model in mind?
    Only if it is used. And also, only if it is used in the correct sequence.
  5. Paul

    Paul Guest

    I do. I just installed a Kubota 30KW diesel generator for a customer and it
    with a 200amp Cutler-Hammer ATS that uses two 225amp MCBs with a stupid
    see-saw mechanism that is operated by a small shaded-pole motor with a crank
    and limit
    switches. I must say I was not impressed when one of my mechanics had to
    manually trip the
    see-saw (to gain access to the terminal insulator guard) and the pivot bolt
    broke off.
    I told the customer that he better hope that doesn't happen during automatic
    See for yourself:
  6. I tried unsuccessfully to find the post of the individual who stated
    that a lineman was killed because he had an inadequate ground in a
    situation where there was a back feed from a home generator. I would
    be interested in reading any written report but the root cause was not
    the home generator but the inadequate personal ground.

    I am writing this with a gas driven generator supplying my house in
    order to burn up some old gasoline. I have tried to keep the lineman
    fatalities to less than 10.

    I never qualified as a journeyman lineman but I did spend a lot of
    time as a ground man and then managed transmission line crews after I
    received my EE degree. I did though join the "Bird On The Line" Club
    when I touched 345 kV from an insulated bucket. I also played a key
    role in the development of 765 kV hot stick tools and practices.


    John Phillips
  7. Guest

    Wow! That sure looks ugly. Thanks for the link!
  8. Guest

    Thanks! That looks good. I hope it is made better than the one
    Paul described where the pivot bolt broke.
  9. Gunner

    Gunner Guest

    Did all the magic smoke leak out of the wires?


    "At the core of liberalism is the spoiled child -
    miserable, as all spoiled children are, unsatisfied,
    demanding, ill-disciplined, despotic and useless.
    Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
  10. Tim May

    Tim May Guest

    Darwin plugs often lead to this result, almost as if Sir Charles had
    laid out the design in 1859.

    Negroes seem to have a close affinity with Darwin, strangely enough.

    --Tim May
  11. Roger

    Roger Guest

    Your best and safest way is to have two receptacles side by side.
    then you have your Grid power powering up one receptacle and your
    generator powering up the other receptacle. when the grid goes down,
    unplug from the grid receptable and plug into your generator plugin.
    then it don't matter if you forget anything. the only thing that can
    happen at this point is that you'll run out of gas/oil for your generator.

    That is the cheapes safest way. AT no time should you have a double
    ended male cord. That is too dangerouse, specially if you have kids in
    the neighbourhood
  12. Guest

    The BEST way is to use a transfer switch. The problem
    with the two receptacles side by side approach is that
    hard wired equipment - such as the control for your
    heating system, circulator, igniter, blower (if so equiped) -
    won't get power. In addition, the two receptacles side by side
    approach is limited. By the time pay for the wiring
    for enough receptacles to make practical use of even a small
    5 kw generator, you'll spend more than you would if you had
    a transfer switch installed.

    The OTHER problem with the side by side receptacles is it
    almost screams for a double male, which, as you said, should
    never be used. But when one has been without power for enough
    time and is cold because the thermostat won't work, guess
    what happens.
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