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  • bobcat as whole house generator?

    New here, just purchased a late model used Bobcat 225g with a14-50r 220v 4 wire receptacle. What exactly does a full kva plug kit do? Connect neutral to ground? Why does this make for "full kva"?

    Want to back feed house breaker box thru a 50 amp DP breaker using an interlock to make sure main breaker is off first. Neutral and ground from the generator connected to the house "ufer" and ground rods, I think. What is this generator going to think of unbalanced 120v loads, which I will try to minimize,
    originating in the breaker box? Thanks

  • #2
    Not completely sure what your trying to do but the machine only puts out 35 amps of 230, and thats what you would connect to a breaker box via some sort of disconnect.

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    • #3
      "Generator Transfer Switch"

      I think what you are looking for is a "Generator Transfer Switch"
      to provide positive isolation between generator and utility lines.... otherwise you might backfeed and kill a lineman..

      Here is an overview

      http://www.electricgeneratorsdirect....er-Switch.html

      something like this would probably do the job for you ...

      http://www.northerntool.com/shop/tools/product_200196674_200196674


      Last edited by H80N; 12-05-2014, 06:25 PM.
      .

      *******************************************
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      • #4
        Square D and other manufacturers offer a breaker interlock to assure the main disconnect is off when the generator breaker is on. This device takes the place of the transfer switch, and service disconnect we otherwise need. Cost is about 1/6 that of a service disconnect, and transfer switch. Some panels built before these devices came on the market can be retrofitted. I think three wire where frame and neutral are bonded is common in small portable generators. Four wire is another good way to do it. Full output only refers to the capacity of the cord / plug is equal to the generator output.
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        • #5
          The Full kva plug kit is to convert the 4 prong 110V/240V outlet on the Bobcat 225 to a 3 prong 220V outlet for use by 220V welders. I haven't seen the pin out for it, and don't have one to check it out - but I suspect the neutral pin from the Bobcat receptacle is just not used in the cable since it's not necessary for a 220V welder.

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          • #6
            I'll check tomorrow.
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            • #7
              The output voltage is regulated indirectly based on the additive current of line Y and line X going through circuit breaker 1 which in turn decides how much voltage to supply to the rotating field (the windings that spin).

              The design of the alternator is very similar to other 120/240v alternators. It has a rotating field coil and a stator which is split into several different coils (for welding and for the sets of 120v at 180 degrees apart.

              Due to this design, if you run an imbalanced load, say 5A on one leg and 25A on the other leg, the leg with the lower load will run at a higher voltage and the leg with the higher load will run at a lower voltage. You can get way out of tolerance if your loads are not relatively matched. Check the two legs inside the breaker box for balanced voltage. If they are way different, say 108v and 132V, remove a load from the side with the drooping voltage and add it to the side with the higher voltage and they will get closer to 120/120.

              80% of failures are from 20% of causes
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              • #8
                Most equipment will function acceptably with a variation of 10% plus or minus. I know of no case where imbalanced load has damaged anything. I did have a used generator, I checked voltage at the generator, not at the load center. I turned on the transfer switch, all was well for 1/2 hour then some lights went dim, others got bright. I ran like He!! to turn it off. The neutral conductor was loose at the receptacle. With no centertap neutral, it became a 240 volt series / parallel circuit. Balanced 120 volt load in series would not be too far out of whack. Imbalanced series circuits see wild differences in voltage.

                A microwave, TV, and some light bulbs later, I had learned an expensive lesson.
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                • #9
                  Thanks for all the help!!

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                  • #10
                    When your checking the plug make sure you don't have a Bobcat 3 phase model that puts out 480 Volts.

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                    • #11
                      As I eluded to in anther thread, a Bobcat is a fine generator and great for real work but under stress sucks gas when you need a few watts. Ok or acceptable when there is real work going on and if you already have it. I should be looking as we speak for a couple cheaper to operate units.

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                      • #12
                        glad someone asked this question first i to have a bobcat and was wondering if i would run into problems hooking it up to my house. i already had a 35 amp breaker box to hook to and plan on turning off the main switch comin from the power companies power then turn on my breaker to let power in from my bobcat 250. i know running the bic a/c and the hotwater heater isn't gonna work but i would thing that everything else should run fine.i hope

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                        • #13
                          Originally posted by tommy2069 View Post
                          glad someone asked this question first i to have a bobcat and was wondering if i would run into problems hooking it up to my house. i already had a 35 amp breaker box to hook to and plan on turning off the main switch comin from the power companies power then turn on my breaker to let power in from my bobcat 250. i know running the bic a/c and the hotwater heater isn't gonna work but i would thing that everything else should run fine.i hope
                          It will work fine.
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                          • #14
                            Originally posted by tommy2069 View Post
                            glad someone asked this question first i to have a bobcat and was wondering if i would run into problems hooking it up to my house. i already had a 35 amp breaker box to hook to and plan on turning off the main switch comin from the power companies power then turn on my breaker to let power in from my bobcat 250. i know running the bic a/c and the hotwater heater isn't gonna work but i would thing that everything else should run fine.i hope
                            In most places it is illegal to hook up a generator without the isolation from the utility line provided by a positive interlock or transfer switch...
                            Check with your local utility company...
                            Last edited by H80N; 12-08-2014, 04:39 PM.
                            .

                            *******************************************
                            The more you know, The better you know, How little you know

                            “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                            Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                            My Blue Stuff:
                            Dynasty 350DX Tigrunner
                            Dynasty 200DX
                            Millermatic 350P w/25ft Alumapro & 30A
                            Millermatic 200

                            TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

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                            • #15
                              There are several ways to make certain that utility power is off when generator power is on. It is critical that this be done by a very competent person, using approved equipment. Do NOT shortcut this. Someone will be killed! Backfeeding a transformer could turn your 240 volts to 14500 volts. DON'T do it!
                              Dynasty 280DX
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                              Twentieth Century 295 AC
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