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Thread: Portable generator bonding queston

  1. #1
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    Portable generator bonding queston

    All the portable generators I have seen have the neutral and ground bonded in the generator.

    Typically, they use a 4 wire circuit from the generator to the transfer switch. The popular UL approved transfer switches don't switch the neutral. Installing them according to instruction, it seems to me that while the generator is supplying power to the circuits in the transfer switch panel, there exists two points of bonding, one in the genny and one in the HO's panel.

    There are thousands of these installed.

    Q1: I don't see a safety issue with having the two bonding points, in fact, I would see a safety issue if the bond in the generator was removed. Am I missing something?

    Q2: Since the transfer switch is a UL listed device, if it is installed according to instruction does that negate the single neutral/ ground bond requirement of the NEC?

    There is not much to the installation of these transfer switches. There is a pair of conductors from each switch (typically 6 switches) that intercepts the desired circuits and are connected in the panel, and one neutral and one EGC going from the panel to the transfer switch. From the transfer switch, 'house wiring' (manufacturers words) connects the transfer switch to an outside receptacle box (supplied with transfer switch) and a cord with L1430 ends on it (also supplied) that goes from the outdoor box to the L1430 receptacle on the generator.

    Q3: Is the above installation code compliant for use in a residence? If not, what, exactly, is the violation.

    Q4: If the above installation is NOT code compliant, what would need to be changed in order to satisfy the code's requirements?

    Here is a typical transfer switch unit: http://www.homedepot.com/h_d1/N-25ec...&storeId=10051

    Click image for larger version. 

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    And, in for the case in question, this generator (labeled that the neutral and ground were bonded in the genny) would be used:

    Click image for larger version. 

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    http://www.generac.com/Portables/GP/...500_and_6500E/

    Thanks!!
    Cheers and Stay Safe,

    Marky the Sparky

  2. #2
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    i thought that the ng bond for the genny was supposed to be removed.

    "Electricity is really just organized lightning." George Carlin


    Derék

  3. #3
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    Quote Originally Posted by jumper View Post
    i thought that the ng bond for the genny was supposed to be removed.
    How, exactly, is that supposed to be done? There are no provisions on any portable generator I have ever seen for this.

    And if it is done, and used without the transfer switch (just plugging stuff into the receptacles) don't you think that would create a grave safety issue, having the frame floating with no bonding?
    Last edited by K8MHZ; 02-16-12 at 12:16 PM.
    Cheers and Stay Safe,

    Marky the Sparky

  4. #4
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    Quote Originally Posted by K8MHZ View Post
    All the portable generators I have seen have the neutral and ground bonded in the generator.
    I just bought a Powermate PM0418000 that has a floating neutral. See this list for which have/have not http://www.generlink.com/CompatibleGenerator.pdf

    Installs that use a bonded neutral at the gen and a solid neutral transfer must be corrected.
    Ron

  5. #5
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    Interesting bulletin from Honda
    http://members.rennlist.org/warren/honda.pdf
    Ron

  6. #6
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    Quote Originally Posted by ron View Post
    I just bought a Powermate PM0418000 that has a floating neutral. See this list for which have/have not http://www.generlink.com/CompatibleGenerator.pdf

    Installs that use a bonded neutral at the gen and a solid neutral transfer must be corrected.
    Cool, that's a great list, but it says that the generator in question has a floating neutral, but the label on the generator says the neutral is bonded to the frame.

    Cheers and Stay Safe,

    Marky the Sparky

  7. #7
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    To further complicate things, the latest portable gensets have GFCI to my understanding.

  8. #8
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    Quote Originally Posted by texie View Post
    To further complicate things, the latest portable gensets have GFCI to my understanding.
    Not on the one I am talking about.
    Cheers and Stay Safe,

    Marky the Sparky

  9. #9
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    Quote Originally Posted by K8MHZ View Post
    Cool, that's a great list, but it says that the generator in question has a floating neutral, but the label on the generator says the neutral is bonded to the frame.

    Use an ohm meter and check from N to G at the receptacle and see ......
    Ron

  10. #10
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    Quote Originally Posted by ron View Post
    Use an ohm meter and check from N to G at the receptacle and see ......
    If I had the generator here I would. In retrospect, I should have done it when I was there.....I just took for granted that the labeling was correct.
    Cheers and Stay Safe,

    Marky the Sparky

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