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Generator Transfer Panel

Discussion in 'Electrical Engineering' started by RPS, Sep 12, 2003.

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  1. RPS

    RPS Guest

    I recently purchased an EmerGen generator transfer panel made by
    Conneticut Electric. While the overhaul contruction is nice, nice set of

    watt meters, etc. I am disapointed in the otherwise cheap installed
    plastic pop-out breakers, and Line/Generator Toggle switches. The box
    arrived with one of the breakers broken, so they have sent me a
    replacment. Upon opening the box to install the new breakers, I was
    disapointed in the otherwise cheap toggle switches which only carry a
    rateing of 16amp at 1/4hp. Now whatever the hell that means is beyond

    Thats seems all well and good when powering from generator power, but
    these toggle switches are also in the chain feeding back to the main
    panel branch breakers when powering from the utility side.
    Seems to me its a disaster just waiting to happen being the weakest link

    in the electrical chain. In startup and surge wattage alone, they are
    underated! When your on the utility power and the electrical chain is
    running through the cheap plastic toggles, imagine powering up a few
    heavy duty items, and that toggle is either going to smoke or short out
    over time. Am I missing something here? This may be an approved transfer

    switch, but is by no means electrically safe.
  2. John G

    John G Guest

    Yes you are missing something.
    You did not correctly specify what you wanted nor tell us what you got.
    Just from your description it appears you got a lightweight board for a
    lightweight job but think you can use it for a heavy weight job.
    Of course it could just be cheap and not even up to the rated specs whatever
    they might be.
  3. RPS

    RPS Guest

    It is an EmerGen 10-7500 watt panel. I don't think it's light, except in its
    construction. This is a load transfering transfer panel meaning it simply
    switches the load between to the two power sources (Gen or Line). My concerns
    are indeed valid. In the Line mode it feeds back to the circuit breaker in the
    main panel. In the Gen mode it feeds through it's own breaker ( in this case
    20amp). My concern is the electrical rating of the each toggle switch in the
    unit which is rated at 16amps at 1/4 horse. The toggles are the weakest link
    when utilizing line power. Would't you agree on that? What is the sense of
    having a 20 amp circuit making a connection through a switch that is rated 16
  4. RPS

    RPS Guest

    Because they don't sell them here, unless your speaking of a double-throw switch.
    The cost and installation costs is prohibitive. Hindsite is always 20-20. Best
    residential equipment I have seen for my particular application is a Sqaure-D Gen
    Panel, which is a true sub-panel to the main loadcenter, but again costly. All the
    NEC requires is a positive lock than prevents simultaneously connecting backup power
    to utility power and is usually achieved by a latching device. The solution you
    proposed is really overkill for me, since I am only powering 6 essential circuits
    and the need to switch the entire distribution system is not needed. A lot of these
    so called generator products on the market are pure hype, marketing, and simply
    trying to instill fear. Now I can fully understand why so many people simply
    backfeed your homes. Killing the MAIN absolutely disconnects the utility side power.
    The real danger is inadvertently connecting both sources usually by human error.
    After all thats all a generator sub panel really is. Two Breakers one of which is
    feed from the main panel supplying the sub-panel, and the other breaker connected to
    the backup power source with the difference being an interlock preventing both from
    being on at the same time! Selected circuits are then relocated to the sub-panel. So
    all the hype and bull shit that the springs or contacts in a breaker can stick and
    create a hazard for the lineman, is nothing more than bullshit since that could
    concievably happen anyway regardless of what your using unless you kill the MAIN
  5. RPS

    RPS Guest

    I agree with you John which is why I posted in the group to begin. Doesn't make
    any sense in any practicle electrical terms to me. Meters are 3250 watts on each
    leg. Still seems electrically unsafe to me.
  6. albown

    albown Guest

    Is it possible that all the toggle switches carry is the load for the coils
    for the unit? I strongly doubt that they carry the full rated current load.
    I used to work for an OEM and our control circuits were generally #14 gauge
    or smaller for a reason. They were controls, not for powering anything. As
    for the construction, is there a UL-CSA label? If so then it has passed the
    requirements for the job established by the testing agencies. If there is no
    UL-CSA label then.......

    Plastic pop out breakers..... What were you expecting? Bolt on's? For
    residential work stab in, pull out breakers are fine. You already admitted
    that a double pole double throw switch was expensive. (my personal choice
    for this situation)

    C.E. has been around for a long time. (I have been in the trade for 30 +
    years) Their fusible pullout disconnects used to be the cheapest model on
    the market, completely legal just the least expensive. I have used 1000's of

    As for the toggle switch rating, switches are rated for their ability to do
    work. Controls do not need much of an amp draw. I am sure the switch was
    chosen for the job and the price that they pay for it. Go to WW Grainger's
    and look at all the toggles available. Litterly tons of them by every
    manufacture in the world.

    I suggest you complete your installation. Then test the installation, at
    least 5 times with different situations and see what happens. If your still
    concerned call the code official and or a licensened electrician for an

    Do not forget the grounding issue with the generator. You can not just drive
    an ground rod at the location and call it good. I believe in (in your case)
    3 pole disconnects. 2 hots and the neutral. Having a solidly made neutral
    with 2 sources of power can be a problem. If your neutral is not isolated
    from the power companies wiring (by a means of disconnect) when on the
    generator, you can and will in certain instances induce current and voltages
    back on the grid. Granted they are small, but if your line man is working on
    your transformer and gets zinged. I guarantee that you will be in court with
    the utility. I have been nailed by this in the past.

    My view from the cheap seats.
  7. RPS

    RPS Guest

    Thanks for your comments however, the power companies neutrals are not isolated
    in ANY of these residential generator transfer panel solutions, or add-in
    generator sub panel solutions. In fact they are all bonded together at the main
    panel. And I have looked at them all (GenTran, EmerGen, Square-D, Cutler Hammer)
    Perhaps they are in utilizing what you are describing in the form of a master
    disconnect, but thats not required. As far as grounding the portable
    generator....the frame must be independently grounded. It's amazing you can talk
    to four different electricians and all of them will give you a different take.
    So which is the right way?
  8. RPS

    RPS Guest

    I agree with you 100% !!!

  9. RPS

    RPS Guest

    Ahhh...they must be legal and meet NEC code requirements or they wouldn't be allowed to
    sell and distribute them in any particular state! I can't speak for local ordinances or
    local building code. It would be informative for you experts to research and look at some
    of this merchandise before offering...oh yes another non factual opinion beacuse I have
    simply heard it all.
  10. Sorry but Killing the MAIN in a residential distribution panel is
    I don't believe that is completely correct. Many transfer switches are made
    up of breakers connected in one way or another. I have supplied many of
    them in equipment packages in the past as per specs for public works jobs.
    Also in industrial manufacturing plants it is done very often.
  11. RPS

    RPS Guest

    This sounds like the best solution. Could the Double Throw simply be wired back
    to main load center eliminating any need for a sub-panel? In others words I just
    want to disconnect the whole house.
  12. Mark or Sue

    Mark or Sue Guest

    Yes it can, but it has to be rated the same as your electrical service which
    is typically 100A or 200A. Harbor Freight Tools has a Cutler Hammer manual
    transfer switch in 100A for $199 and 200A for $299. These are huge and in
    raintight enclosures. They must be mounted adjacent to your main disconnect
    because they have no fuses or breakers inside of them. Needless to say, you
    will have to pull you meter to install this.
  13. albown

    albown Guest

    See below

    Yes it can, HOWEVER, there are going to some issues. Trying not to omit the
    important steps you could do this. CHECK with the utility for their
    regulations. GET A PERMIT if required. Remove the meter and remove all the
    load wiring from the meter base to the main circuit breaker. Land these in
    the new 3 pole double throw service rated switch. Wire the load side to your
    main circuit breaker and the other set of lugs to the generator your going
    to use. Make sure that the grounding is done correctly at the generator. Now
    you can have 2 sources of power and isolation between them. It is manual but
    that should be ok and the way I would want it. The power company should be
    happy cause they have visible blade disconnection. A requirement here for
    islanding, ( that is what they call it here ) . This equipment is not small
    nor is it pretty.

    You should look into the requirements for paralleling, just for fun. Now
    that gets crazy. I had a client that has a 900 kw gen set. The utility was
    going to offer credits and incentives for the conversion. The customer
    wanted to parallel and/or island as the condition warranted. The
    conversion of his main service was 220K. The additional controls was another
    75K. The kicker was the county licensed his generator for standby only not
    prime power. Our local county has a regulation that when you hit 75 tons of
    pollution in a year you were considered a utility company. Needing an EPA
    impact study and all the controls and clean up stuff that is required. His
    generator would have made 75 tons of pollution every 7 days according to the

    Good luck, please let us know how this goes.
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