another grounding question

I have a 12volt distribution box (grounded w/ an 8' rod) and a 120 volt distribution box (grounded w/ a separate 8' rod). My generator is not yet grounded and located 2' from the grounding rod that is used to ground the 12v equipment. Its 40' from the rod that the 120v equipment is grounded to.

Would there be a problem grounding it to the same place the 12v equipment is or do I need to run it to the other rod?

Thanks!

Chris

Comments

  • BB.BB. Posts: 27,335Super Moderators admin
    Re: another grounding question

    Hmmm, a difficult question to answer.

    What kind/model/size of genset do you have? Typically, generators larger than ~3.5kW or so have the AC neutral grounded to the frame of the generator.

    Usually, the correct way to connect such a genset (as backup behind a transfer switch to utility panel) would be to lift the neutral to frame ground at the genset and let the AC main panel ground to earth ground be the "one ground bond" point.

    And then attach the genset frame to the same ground rod used by the AC panel.

    Secondly, I would consider tying a 6 awg wire from the DC ground rod to the AC ground rod. I do not like floating ground between to power systems in the same home. In most cases, having the DC and AC grounds bonded together at one point is safer and better.

    If your DC grounded equipment and your AC grounded equipment is not intermixed--then you could let the DC ground float wrt the AC ground.

    In any case, the genset earth ground wire should go back to AC ground rod for safety (just run the green wire with the rest of the Hot/Neutral/Hot wiring).

    This thread has a very nice (long) discussion about proper generator grounding.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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