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Thread: generator and ATS install

  1. #1
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    generator and ATS install

    Upon installation of an ATS,and generator the local inspector found deficiencies of the installation. First some background info, this is a residential application and is an optional standby system. The existing service is single phase 600 amp. Three conduits lead from the metercan to mainbreaker panelboards in the upstairs laundry. The mains are grouped here.
    I broke into the conduit outside feeding the panel the genset would supply during an outage. I installed a j-box and piped over to the ATS. The ATS has a breaker factory installed in it. The utility power is connected to this breaker.the gen set is connected via a whip, and the load side of the ATS feeds the panelboard upstairs,very simple. Here are the issues the inspector cited. #1 mains are no longer grouped,#2 j-box and pipe can't share both sets of conductors,#3panelboard in laundry is now a subpanel and grounds and neutrals must be seperated.My questions are should the breaker in the ATS be considered a main,the ATS could have been ordered without this breaker.If it is what about 230.72b? If it isnt a main then the panelboard grounds and neutrals wont have to be seperated,and the conduit sharing both sets of conductors shouldnt matter.Another thing is that if you open the breaker in the ATS the genset starts and transfers power to that panel, so how can you consider it a main.The inspector wants a 600 amp disconnect installed and panels to be treated as subs, and ground conductors pulled to these panels.
    thank you for your thoughts and time

  2. #2
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    The inspector is correct on all three points.
    Don
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

  3. #3
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    Quote Originally Posted by fendrick
    My questions are should the breaker in the ATS be considered a main,the ATS could have been ordered without this breaker.
    If you had done that, then you would have needed a separate disconnect between the meter and the ATS. The first thing the service cables need to hit after the meter must be "suitable for use as service equipment." The main breaker nakes this ATS suitable for use without a disconnect ahead of it.

    Additionally, the ground and neutral must be split at this point, and yes, every panel downsteram has been rendered a sub-panel, whether it has a redundant main or not.

    . . . what about 230.72b?
    There is a point here. The wording seems to support your side of point of contention #1. The question, I believe, is whether an optional standby generator is considered a service for this discussion.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  4. #4
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    If you have taken the Service conductors and installed them into the ATS, and the ATS is suitable as service equipment that is fine. The panels in the house that were service disconnects are now "subpanels" and are not required to be grouped... yes the grounded conductor and the equipment ground conductor at those panels need to be isolated.

    230.7 says that service entrance conductors and other than service conductors shall not be installed in the same raceway or cable. You will need to read the definition of raceway in Art 100 to see what it includes as "raceway".
    Instructor, Industry Advocate

  5. #5
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    "I have learned, in whatsoever STATE I am, therewith to be content". :) Philipians 4:11
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    Question

    This is an interesting topic. I m still learning here. But i was always taught that the generator would be looked as a "sevice" and any panel comming from there WOULD be the "service" panel. The only point i can see is when normal power is on, that the panel up to laundry would then and ONLY then be looked at as a 'sub' panel. And in that case the grounds and neutrals would have to be seperated.

    And i agree, why would the mains need to grouped, if this was a subpanel (seeing how hes having you seperate the grounds and neutrals) ????

  6. #6
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    Quote Originally Posted by fendrick
    Upon installation of an ATS,and generator the local inspector found deficiencies of the installation. First some background info, this is a residential application and is an optional standby system. The existing service is single phase 600 amp. Three conduits lead from the metercan to mainbreaker panelboards in the upstairs laundry. The mains are grouped here.
    I broke into the conduit outside feeding the panel the genset would supply during an outage. I installed a j-box and piped over to the ATS. The ATS has a breaker factory installed in it. The utility power is connected to this breaker.the gen set is connected via a whip, and the load side of the ATS feeds the panelboard upstairs,very simple. Here are the issues the inspector cited. #1 mains are no longer grouped,#2 j-box and pipe can't share both sets of conductors,#3panelboard in laundry is now a subpanel and grounds and neutrals must be seperated.My questions are should the breaker in the ATS be considered a main,the ATS could have been ordered without this breaker.If it is what about 230.72b? If it isnt a main then the panelboard grounds and neutrals wont have to be seperated,and the conduit sharing both sets of conductors shouldnt matter.Another thing is that if you open the breaker in the ATS the genset starts and transfers power to that panel, so how can you consider it a main.The inspector wants a 600 amp disconnect installed and panels to be treated as subs, and ground conductors pulled to these panels.
    thank you for your thoughts and time
    The inspector is right.To fix this you need to group them.How depends on how easy it would be to install perhaps one 600 amp disconnect just after the meter.Next is to pull a ground wire to all the SUB panels.

  7. #7
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    Based on Fendrick's original post, it sounds like the generator is feeding only one panel.

    My thought is to put the transfer switch next to the panel served, conduit would run from the transfer switch down to a remote generator connection.

  8. #8
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    The panel on the load side of the ATS is a subpanel. The ATS in this example is the service disconnect. The load side conductors are feeders, not service conductors.
    Only service disconnects need to be grouped...
    Instructor, Industry Advocate

  9. #9
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    It sounds like the ATS was only intended to serve one of three panels. I'm assuming it's rating is that of the one panel. It is a service disconnect for that panel and that panel becomes a sub-panel. My suggestion of mounting the ATS next to the panel served maintains the grouping of the disconnects and I believe eliminates the need for a 600 amp disconnect.

  10. #10
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    Quote Originally Posted by Pierre C Belarge
    Only service disconnects need to be grouped...
    Right. The problem here is that the two non-generator panels have their disconnects indoors, in the interior panels. The ATS's utility disconnect will connect between the meter and the ATS, outdoors, away from the two interior panels.

    This is where the suggestion of placing the ATS indoors, beside the panel it will be serving, rendering the disconnects once again, or still, grouped. The disadvantage is the need to run the generator-ATS feeder to the inside, which raises . . .

    The next question: will the generator require a disconnect of its own, which means that there will once again be a disconnect outside, and does this disconnect fall under the same requirement as grouping the utility disconnects?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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