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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. daestrom,

    Actually, on high voltage transmission, it is safer to ground the
    conductors on the tower being worked rather than the two adjacent
    towers. This is because it puts less resistance to ground from the
    conductor in the event of an inadvertent tenderization. It also saves
    a lot of time.

    The ground conductor has to be sized to be capable of conducting the
    maximum available short circuit current for a fair amount of time.


    Regards,

    John Phillips
     
  2. Guest

    I seem to average one 4-14 hour power outage every other year.
    Other than that I loose power 3-5 times a year for less than an
    hour.

    With those kinds of outages, I couldn't justify the cost of an industrial
    generator and a professional panel install, so I bought a post y2k returned
    Coleman generator at Home Depot and came up with a DIY solution.

    I'm cheap, but I wouldn't take the risk of backfeeding the whole house.
    I run the 20a 240v output from the generator into my basement. There I
    split it into two 120v feeds. One 120v feed powers a twist lock outlet
    next to the furnace. The other 120v feed powers four outlets at the top
    of the basement stairs.

    I put my furnace on a 120v twist lock plug and put a twist lock outlet on
    the existing furnace circuit. In the event of a power outage I simply
    unplug the furnace from the grid and plug it into the generator plug.

    My fridge, TV, dish network receiver, and sump pump are within 20' of the
    four outlets at the top of the basement stairs. The sump pump is normally
    powered off an extension cord into a ground fault outlet at the top of the
    stairs, and two extra 25' extension cords are hanging on the wall.

    Its not an automated solution, but as long as I don't fall down the basement
    stairs in the dark, it seems like a safe solution.
     
  3. A real transfer switch is an enclosed multi pole double through switch.
    They are built so that it is not possible to throw them all the way
    from one set of feeds to the other. You have to throw them to center
    off and then to the other supply. When the switch is in the center off
    position you can open the cover on the cabinet that is it's enclosure.
    You would then see that each pole is a hinged blade that can be
    positioned in one contact jaw, centered off, or in the other contact
    jaw. Since the pole of the switch cannot be in two places at once and
    it is not long enough to connect both contact jaws together it is
    extremely difficult to cross connect the two power sources together.

    Compare that to the construction of a molded case circuit breaker. It
    is impossible to look at the operating mechanism; it can, in fact, fail
    closed; it provides only a single gap between the two power sources.
     
  4. NO. I'm hoping that if you undertake to back feed your houses wiring
    that if anyone is killed it is you. I never said you should be killed
    for asking questions.

    As for providing you with the applicable facts in an internet posting it
    simply cannot be done. I have been installing and servicing power
    systems for most of my adult life. It would take a book to provide you
    with all of the sneak current paths I have encountered over those years.

    I thought it was pretty glib of you to say that only stupid people would
    forget to open the main breaker. Fatigued, drug or alcohol impaired, or
    over stressed people who are not stupid can and have made that mistake.
    Not all panels have a single main breaker. Some have four or six and
    one of those mains would be the dryer outlet while another would be the
    stove outlet and so forth. In order to get power into those homes you
    would have to close one or more of the main breakers each of which is
    connected to the service entry conductors from the service drop or
    lateral and thus to the transformer. Federal Pacific two pole breakers,
    of an extensive number of production runs, will fail closed after a very
    limited number of manual or automatic operations. I have seen other
    brands fail closed as well usually from internal corrosion secondary to
    water following the service conductors to the main breaker from the
    service entry cable.

    I am a firefighter and I have responded to a child shocked by a suicide
    cord as well as to a tree worker electrocuted by a generator back feed.

    The injured child was shocked after a playmate found a double male cord
    hanging in the garage and plugged it in. When the child touched the
    exposed pin on the other end he received a shock that fortunately did no
    permanent harm. He was treated for a small The cord had been made up
    by the landlord to bridge out an open circuit in order to avoid the cost
    of an electrician on a service call. The circuit continuity had failed
    at a push in terminal receptacle. After the tenant had demanded the
    repair of the circuit through the city housing office the landlord had
    stored the cord for future use.

    The back feed death occurred during the 1988 micro burst clean up in the
    Maryland suburbs of Washington, DC. A tree trimming crew was clearing
    limbs and trees off of power lines so that they could be rebuilt. The
    power was out over a very large area and some of the sub stations had
    been taken off line and grounded out to facilitate the tree work. When
    my engine arrived on scene we were met by the owner of that family
    owned, two truck, tree trimming company begging us to get his son down.
    He had come in contact with a 13.9 kilovolt line that was energized
    through a neighborhood transformer from the only service drop that was
    still intact. That drop was to a home were the back feed was coming
    from. Another fire fighter used one of our fiberglass pike poles as a
    hot stick to open the fuse above the transformer while I pulled the
    homes meter. We then brought the tree worker down and attempted CPR and
    applied an automated external defibrulator. The tree worker did not
    recover and was pronounced dead after nearly an hour of resuscitative
    effort at the hospital emergency department less than five minutes from
    the scene.

    Several utility workers have been killed by back feeds from generators.
    A search of the FACE reports on the OSHA web sight will bring up
    several examples. In one case, in Georgia, the line had been grounded
    out but the lineman had failed to notice that the grounding wire on the
    pole had been broken by a motor vehicle. Since that incident occurred
    during the clean up after hurricane Hugo the Multi Grounded Neutral
    (MGM) that should have provided a perfectly safe ground had been broken
    into short segments by falling limbs. With the only grounding electrode
    conductor that was still attached to that segment of the MGM damaged
    near the base of the pole the protection of the grounding was lost.

    I'm a sore looser when it comes to the death of young healthy people who
    are killed by the negligent actions of others.
     
  5. John

    John Guest

    I put my furnace on a 120v twist lock plug and put a twist lock outlet on
    That is a code violation. I don't know why exactly, but it is.
     
  6. Gunner

    Gunner Guest

    Bravo. Quick, cheap, expedient and most importantly, safe.

    Gunner

    "In my humble opinion, the petty carping levied against Bush by
    the Democrats proves again, it is better to have your eye plucked
    out by an eagle than to be nibbled to death by ducks." - Norman
    Liebmann
     
  7. Friday

    Friday Guest

    Aside from the two-box LAN in use (one mac and one XP box) I must have
    at least five old (working) 'putahs around here I could use. I'd hate
    to lose one of my primary machines though.

    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  8. Friday

    Friday Guest

    I always keep plenty of fresh flashlight batteries and a few spare
    bulbs on hand.

    PLUS, I have this neat little flashlight that doesnt use batteries or
    bulbs. Magnets charge a capacitor which lights up an LED. Supposed to
    be good for several HUNDRED thousand hours.
    I just did something similar with the furnace yesterday (split the main
    line and put in male and female plugs), Tested it and it works fine.
    For everything else, extension cords will do the job.
    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  9. Friday

    Friday Guest

    That is a code violation. I don't know why exactly, but it is.
    [/QUOTE]
    The guy fronm the power compnay was here yesterday doing some other
    work and he looked at it and said it was fine.
    <Shrug>
    Of course he's not an inspector.
    Wonder why that would be against code.
    Local code?

    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  10. Beachcomber

    Beachcomber Guest

    I don't claim to be a NEC code expert, but last time I checked, a
    furnace was considered a "stationary appliance" (like a dishwasher)
    and thus must accordingly be connected with a hard-wired connection.

    Lots of furnaces are wired to accept 240 V, so a 120 V. twist lock
    plug would be illegal in these cases.

    Does anyone know of a rule that would allow an exception?

    Beachcomber
     
  11. John

    John Guest

    ANSI Standard Z21.47 does not allow cord and plug connections for gas
    furnaces.
    NEC 400.7(A)(8) and 422.16.(A) allow flexible cord only on appliances
    specifically intended for them, and forbid them on appliances that cannot be
    readily moved.

    Is that specific enough. No, it is not a sign that I don't have a clue; it
    simply means that knowledgable people don't need the references, and others
    don't want them. I guess you fall into the class of ignorant people who
    don't even know it.
     
  12. Friday

    Friday Guest

    How about the rule of survival; i.e.: not freezing to death.

    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  13. John

    John Guest

    Apology accepted.
    As I said in the first post, I really don't understand why it is forbidden;
    it just is.
    Presumably it is so you can't accidentally leave it unplugged, but you can
    just as easily leave it turned off or with breaker open.
     
  14. Louis Bybee

    Louis Bybee Guest

    It is also possible to receive special consideration for certain cases from
    the AHJ for using a cord and plug connection for fixed equipment that would
    normally require a hard wire connection.

    I have never seen it allowed in a residential application, but I have
    frequently seen it in industrial situations where equipment is fed from bus
    duct overhead, and while the equipment is fastened to the floor it is
    regrouped occasionally for production reasons, moved out for repair, or
    power feeds are disconnected to allow other oversize equipment to be moved
    about.

    Louis--
    *********************************************
    Remove the two fish in address to respond
     
  15. The problem with building idiot resistant gadgets (like the safety grip
    handles on lawn mowers) is that we keep getting better idoits. Like folks
    who wire down safety handles.

    You can do what I did: Anything you think you might want on the generator,
    wire it in with extension cords and plugs. Refrig, couple lights, computer,
    etc.

    I did have to do some wiring for the furnace, had to put a cord and plug on
    the furnace, and wire a socket. I know it's not code, but it's been
    perfectly safe. Better than the last nine years I lived here, I didn't even
    see that the guy who put in my furnace didn't use a romex connector. The
    14/2 was rubbing on the punch out.

    --

    Christopher A. Young
    Learn more about Jesus
    www.lds.org
    www.mormons.com


    That you, or someone WILL forget to open that breaker and kill
    someone. At which point the heavens will open and your life (and the
    wife and kids of the dead people) will be turned to shit, now and
    forever amen.

    Not to mention if the power comes on, and you happen to still be
    connected..the transformer on the pole explodes milliseconds after
    your genset turns into a small but lethal fireball.

    Go to Home Depot, etc and buy a transfer switch. They are commonly
    available now for less than $200. You can do it yourself if you are
    handy.

    Oh..and never check for gas leaks or the level in your fuel tank with
    a lit match. Based on your post..I had to add that, in order to save
    your life or the life of someone else, as it appears you dont think
    very far ahead. Shrug.

    Gunner

    "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
     
  16. I know it is -- I also don't know why it's in the code. My refrig, toaster,
    hair dryer, and chicken plucker all have plugs.

    --

    Christopher A. Young
    Learn more about Jesus
    www.lds.org
    www.mormons.com


    That is a code violation. I don't know why exactly, but it is.
     
  17. Friday

    Friday Guest

    Any problems running your cmputer(s) off the generator?
    I've read so many articles insisting this is a no-no (for any sensitive
    electronics, even TVs).

    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  18. Nick Hull

    Nick Hull Guest

    It should meet code IF you put wheels on the furnace; then it cannot be
    considered stationary.
     
  19. Friday

    Friday Guest

    "sinusoidal voltage"??????

    --
    #####################################
    "The people cannot be all, & always well informed. The part which is wrong will
    be discontented in proportion to the importance of the facts they misconceive.
    If they remain quiet under such misconceptions it is a lethargy, the forerunner
    of death to the public liberty. What country before ever existed a century & a
    half without a rebellion? & what country can preserve it's liberties if their
    rulers are not warned from time to time that their people preserve the spirit
    of resistance? Let them take arms... The tree of liberty must be refreshed from
    time to time with the blood of patriots & tyrants"
    -- Thomas Jefferson
    #####################################
     
  20. Honda EU3000is:
    http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=eu3000is

    Two EU2000i generators can be paralleled to double the output. I'm
    not sure about the EU3000is.

    R,
    Tom Q.
     
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