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Thread: Generator, ground rod or not

  1. #1
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    Generator, ground rod or not

    I need your help to clear up this ground rod install at a generator.
    Our installs are on irrigation systems, supplied from a 3 phase, 4 wire, 480 volt engine mounted generator. The generator is only supplying the 3 phase 480 volt load.
    The irrigator is anchored to a concrete encased electrode system, with a #4 cu. from the control panel to the cee. If the well is at the site, the well casing is also connected to the cce, so now there are 2 electrodes in close proximity.
    Should the generator frame;
    1. Have its own ground rod driven and be separate, not connected to the other electrode system? I'm pretty sure this is improper.
    2. Be connected to the other system without an additional rod? Just an external conductor from the generator frame connected to the electrodes.
    3. Not connected to the gec system at all except through the equipment grounding conductor run with the supply conductors from the generator to the irrigator? The EGC is connected to the generator frame in the wire box of the generator.
    Thanks

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    I don't believe there is a requirement that a generator have a separate grounding electrode system installed. So presumably one could use the existing GES.
    Bob

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    Okay, but do I need an GEC from the generator frame at all. There is an EGC in the supply from the gen. to the irrigator?

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    Quote Originally Posted by dave121 View Post
    Okay, but do I need an GEC from the generator frame at all. There is an EGC in the supply from the gen. to the irrigator?
    It depends on whether it is an SDS or not.
    Bob

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    I believe it is a SDS. It is the only source to the irrigator, other than grounding and bonding.

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    I believe it is a SDS. It is the only source to the irrigator, other than grounding and bonding.

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    Sorry for that double reply.

  8. #8
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    Quote Originally Posted by dave121 View Post
    I need your help to clear up this ground rod install at a generator.
    Our installs are on irrigation systems, supplied from a 3 phase, 4 wire, 480 volt engine mounted generator. The generator is only supplying the 3 phase 480 volt load.
    The irrigator is anchored to a concrete encased electrode system, with a #4 cu. from the control panel to the cee. If the well is at the site, the well casing is also connected to the cce, so now there are 2 electrodes in close proximity.
    Is the equipment in a building and the concrete encased electrode part of the structure for the building?
    Should the generator frame;
    1. Have its own ground rod driven and be separate, not connected to the other electrode system? I'm pretty sure this is improper.
    The generator frame must be bonded to a grounding electrode system.
    2. Be connected to the other system without an additional rod? Just an external conductor from the generator frame connected to the electrodes.
    If the generator has a main breaker, the grounding electrode conductor must be connected to the system at the generator and the system bonding jumper will be located at the point of connection of the GEC. If there is no main breaker at the generator, the GEC connection and system bonding jumper would be located at the system main disconnect. In that case, there would be a system bonding jumper run between the generator and the location of the main disconnect.
    3. Not connected to the gec system at all except through the equipment grounding conductor run with the supply conductors from the generator to the irrigator? The EGC is connected to the generator frame in the wire box of the generator.
    Thanks
    The concrete encased electrode and the well casing if available would be the only electrodes required. I expect this SDS is outside, so the rules in 250.30(C) cover the required grounding electrodes.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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    No buildings involved, outside in a field. Generator has a main fused disconnect. We will connect the GEC there.
    Thanks to you all.

  10. #10
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    Quote Originally Posted by dave121 View Post
    No buildings involved, outside in a field. Generator has a main fused disconnect. We will connect the GEC there.
    Thanks to you all.
    Not sure you really have a concrete encased electrode. That must be in a footing or foundation. If the generator is just on a concrete pad, it would be my opinion that you don't have a CEE.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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