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Thread: Separating Ground & Neutrals to Create Subpanel

  1. #1
    DIY Junior Member adsforpay's Avatar
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    Default Separating Ground & Neutrals to Create Subpanel

    I am installing a standby generator. I am using a service entrance rated automatic transfer switch with a main breaker/disconnect. With this arrangement, my current main panel becomes a subpanel. This is a picture of the neutral/ground bus bars in the main panel.

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    As you can see, they are all mounted to the same bare metal plate, so are bonded together. I have installed subpanels before where the panel was threaded to mount a ground bar directly to the panel, but I do not see any provisions in this panel to mount a separate ground bar. All three of the existing bus bars are mounted to the metal plate with screws, so any one could be removed to use as a ground bar. This is a Square D panel, Box # QOB40MW200-2.

    My question is: Would it be acceptable to drill and tap holes in the back wall of the panel to move one of these bars to be a separate ground bar. Even easier would be to use self drilling screws. The bare metal plate that the three bars are mounted to is mounted to plastic, so mounting one bar to the metal of the panel would separate the neutrals from ground.

    It seems the logical thing to do, but I want to know if there is any reason I shouldn't.

    Thanks in advance.

  2. #2
    Jack of all trades DonL's Avatar
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    Not sure why you would need to do that. To add a transfer switch.

    I would say NO that will not meet code, and may not be safe.

    All of your conductors need to be switched in your transfer switch.

    Are you wanting to back-feed your Main ?


    Maybe I miss something, or do not understand ?
    Last edited by DonL; 08-23-2013 at 10:48 AM.
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    DIY Junior Member adsforpay's Avatar
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    Quote Originally Posted by DonL View Post
    Not sure why you would need to do that. To add a transfer switch.

    I would say NO that will not meet code, and may not be safe.

    All of your conductors need to be switched in your transfer switch.



    Maybe I miss something, or do not understand ?
    The transfer switch has a main breaker (disconnect), so it becomes the main and any panel beyond that is a sub panel.

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by adsforpay View Post
    The transfer switch has a main breaker (disconnect), so it becomes the main and any panel beyond that is a sub panel.

    OK.

    So why would you need to move grounds and neutral wires around ?

    This sounds like a problem that JW can help you with.

    I think that you may be wanting to follow code and only bond neutral and ground in the main box.

    Not sure how that works for a transfer switch, If the switchover meets code, You should be OK. My guess is that it does not.

    I would not think that would make your main a sub panel, But I could be wrong. JW would know.


    What is the model of your change over switch ?


    Good Luck.
    Last edited by DonL; 08-23-2013 at 11:46 AM.
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    Electrical Contractor/Instructor jwelectric's Avatar
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    If the transfer switch is rated as service equipment then it will have an off position which turns it off from both the utility and generator without opening anything. The switch will be external. If it is not able to be turned off without opening anything then it doesn’t matter if it has a breaker or two or not it must have a disconnect between it and the meter and one between it and the generator.

    The disconnect between the transfer switch and the meter will be the service disconnect and the bonding and grounding electrode must always take place in the service equipment. The disconnect between the transfer and the generator is required by Part II of Article 225 and must be rated as service equipment Section 225.36

    Depending on the generator and the listing of the generator will determine if the neutral will be required to be switched in the transfer switch.

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    DIY Junior Member adsforpay's Avatar
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    The generator is a Kohler 14RESA, the transfer switch is a Kohler RXT service entrance rated, NEMA 3R, with a circuit breaker behind a door. It will be mounted externally, next to the meter. Current wires from meter to main panel in the house will be rerouted to the transfer switch. New wires from transfer switch load lugs will be routed to the existing main panel. My understanding is that makes my main panel become a sub panel. All I want to know is a proper way to separate the neutrals and grounds in my panel.

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    Electrical Contractor/Instructor jwelectric's Avatar
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    The transfer switch you have listed is not rated as service equipment so look at my last post.
    Quote Originally Posted by jwelectric View Post
    If the transfer switch is rated as service equipment then it will have an off position which turns it off from both the utility and generator without opening anything. The switch will be external. If it is not able to be turned off without opening anything then it doesnít matter if it has a breaker or two or not IT MUST HAVE A DISCONNECT BETWEEN IT AND THE METER and one between it and the generator.

    The disconnect between the transfer switch and the meter will be the service disconnect and the bonding and grounding electrode must always take place in the service equipment. The disconnect between the transfer and the generator is required by Part II of Article 225 and must be rated as service equipment Section 225.36

    Depending on the generator and the listing of the generator will determine if the neutral will be required to be switched in the transfer switch.

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    DIY Junior Member adsforpay's Avatar
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    Quote Originally Posted by jwelectric View Post
    The transfer switch you have listed is not rated as service equipment so look at my last post.
    Is there a difference between "service entrance" rated and "service equipment" rated?

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    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by adsforpay View Post
    Is there a difference between "service entrance" rated and "service equipment" rated?
    Yes. In order to be allowed to be installed as the first disconnect after the meter it must comply with certain rules no matter what the manufacturer calls it. The purpose for it meeting certain criteria is for emergency personal that might need to turn power off to the building in order to put out a fire.

    Read the top of page three of the spec sheet and you will see that it only has utility cut off ability and it does not have an absolute off for both generator and utility.

    Also in order to be automatic transfer the generator must be capable of carrying the entire load being transferred or have load sheading ability. The generator you listed is only a 50 amp generator with the ability to deliver 40 amps of continuous load using natural gas and 58 amps with 46 amps continuous load with LP gas.

    Also remember that just because something will work in no way means that it is either safe or compliant. See this little story;
    Quote Originally Posted by jwelectric View Post
    Another little trick us hill boys are famous for is the three wire circuit to an our building we keep a freezer for the deer meat and have the light three way from house to building.
    Once the black and white wire is connected to the receptacle in the building so the receptacle stays hot all the time we install a light with one wire to the common of the three way at both the building and house. Now connect the neutral to one of the traveler screws keeping continuity for the receptacle and do the same with the hot wire to the receptacle. Draw it out and see that it works.

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    DIY Junior Member adsforpay's Avatar
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    OK, I understand all that. But that still leaves my current main panel being changed to a sub panel. So how do I separate the grounds and neutrals?

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    Electrical Contractor/Instructor jwelectric's Avatar
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    The neutrals will have to be isolated from the enclosure and equipment grounding conductors and the grounding electrode conductor will have to be moved to the service disconnect

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    DIY Junior Member adsforpay's Avatar
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    Quote Originally Posted by jwelectric View Post
    The neutrals will have to be isolated from the enclosure and equipment grounding conductors and the grounding electrode conductor will have to be moved to the service disconnect
    I knew all of that. Look at the original post. My question is, how to isolate the neutrals in the panel box I have? Can I mount a bus bar to the back wall of the box?

  13. #13
    Electrical Contractor/Instructor jwelectric's Avatar
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    There are many different ways to accomplish a compliant installation. What matters is the end result which will mandate that the neutrals be isolated from the enclosure, grounding conductors, and grounding electrode conductors.

    Remember the generator will not transfer the entire panel without stalling the generator. Knowing this and that some sort of load shedding device must be installed I would recommend replacing everything there and starting from new.

    If I was installing the generator by contract this would be one of the solutions I would present to you and if it was unacceptable then we would sit down and discuss how this generator could be connected to your home in a compliant manner. The conversation would end when we came to the point of only talking about what will work just as this conversation will not lead into a just tell me how to do this in a way that will work.

    I will give guidance only in a code compliant manner. I will not give advice to someone who is going to go head strong in a non compliant installation

  14. #14
    Electrical Contractor/Instructor jwelectric's Avatar
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    In your original post you commented
    Quote Originally Posted by adsforpay View Post
    I am installing a standby generator. It seems the logical thing to do, but I want to know if there is any reason I shouldn't.
    I then went about telling you the code compliant manner in which to install this generator. It is important to make any installation in a code compliant manner for safety reasons.
    90.1 Purpose.
    (A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.
    (B) Adequacy. This Code contains provisions that are considered necessary for safety.

    Anything that does not comply with the code is an unsafe installation. Any installation that does not comply with the code can cause huge problems with homeownerís insurance in the event there is a claim filed. This should be a secondary reason for compliance and the primary reason being the safety of us and our families.

    After I posted the correct manner in which to install this generator you made the comment,
    Quote Originally Posted by adsforpay View Post
    All I want to know is a proper way to separate the neutrals and grounds in my panel.
    I then took the time to explain that the transfer switch is not listed as service equipment and pointed out once again how to make a compliant installation and you then made this statement.
    Quote Originally Posted by adsforpay View Post
    OK, I understand all that. But that still leaves my current main panel being changed to a sub panel. So how do I separate the grounds and neutrals?
    I then told you that the neutrals would have to be separated from the equipment ground conductors in the now remote panel (sub panel) thinking about your original post and this comment,
    Quote Originally Posted by adsforpay View Post
    I have installed subpanels before
    This would lead me to believe that you already know the answer to your question but if you donít, now I question your ability to make this installation. If you donít know the answer to this then how are you trying to make a generator installation?

    Just adding a ground bar is not the answer to your question. The proper manner of installing the generator should be your primary question.

    Now answer a question for me. Is this installation going to be inspected?

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    DIY Senior Member bluebinky's Avatar
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    If it were me installing what you have (myself), I'd be looking at something more like:
    1) Pull a permit.
    2) Keep the existing main panel.
    3) Install a listed sub-panel.
    4) Move the "essential loads" to the sub-panel -- staying under the capacity of the generator.
    5) Ask more questions here.
    6) Listen to JW.
    ...

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