Separating Ground & Neutrals to Create Subpanel

Discussion in 'Electrical Forum discussion & Blog' started by adsforpay, Aug 23, 2013.

  1. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    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.

    P1030647 (600 x 450).jpg

    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. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
    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: Aug 23, 2013
  3. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    The transfer switch has a main breaker (disconnect), so it becomes the main and any panel beyond that is a sub panel.
  4. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX

    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: Aug 23, 2013
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
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    Location:
    North Carolina
    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.
  6. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    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.
  7. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    The transfer switch you have listed is not rated as service equipment so look at my last post.
  8. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    Is there a difference between "service entrance" rated and "service equipment" rated?
  9. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    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;
  10. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    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?
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    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
  12. adsforpay

    adsforpay New Member

    Messages:
    8
    Location:
    Arkansas
    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. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    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. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    In your original post you commented
    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 homeowner’s 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,
    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.
    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,
    This would lead me to believe that you already know the answer to your question but if you don’t, now I question your ability to make this installation. If you don’t 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?
  15. bluebinky

    bluebinky Member

    Messages:
    382
    Location:
    Santa Clara, CA
    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.
    ...
  16. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
    I really do not like the Idea of Auto Switchover when it comes to Generator Power. Unattended operation, is one big reason.

    In a home it can cause Lock Rotor conditions on anything with a compressor, and as JW pointed out stall the Generator or trip its breaker. Then you have even bigger problems, and can end up with nothing.

    It is not that much work to manually start the generator and switch loads to only what is needed.

    I use properly rated extension cords to power only the needed items. It saves fuel and I can suffer a bit until a Hurricane has passed.


    People are spoiled now a days, To each his own.
  17. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey

    You have got to be kidding here......In my area after millions of people suffered thru some severe storms over the last couple years.....Homeowners are buying generators at a very high rate and a very large percentage are larger units with Automatic Transfer Switches....and yes they now offer load shedding modules and the installs are not simple.....The company I work for services...sells....repairs.....and has installed hundreds of units......No way the average homeowner wants to do anything but pick up the phone if their generator does not work in a power failure.....Our phones never stopped ringing in a Storm like Hurricane Sandy......except during the actual event when everyone was hunkered down....Our commercial accounts are even more demanding and we service hundreds and hundreds of machines and switchgear......
  18. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    I have two generators and use cords when needed. I do not have any type of transfer switch. Cord from generator to appliance or lamp.

    What would people do in case of a solar flash?
    gee no tv tonight.
  19. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey
    What you and I do at home in a power outage is not the issue...

    What others request and are willing to pay money for.....is what I am speaking about...

    What about Essential services.......Like Police....Fire....Emergency...Health care providers.....Hospitals...

    They ALL have backup power with automatic transfer switches.......Some have redundant systems

    We have clients that spend thousands and thousands of dollars so they are never without power and they are data centers....

    After Hurricane Sandy they were so paranoid about possibly losing power in another possible storm they went on generator power before the storm and had us put men on site 24/7 until well after the storm......They even have backup machines in place to backup their backup!!! We have one in our yard now for one of those companies.....they have no room so we have it.....500KW unit on a trailer.....just for them incase their regular unit were to fail.....

    Money talks......

    So why should a homeowner not have the option of having the same capability....They do and if they are willing to spend the money for a proper install it gets done....
  20. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    Here-in lies the truth of the matter. The big problem is most don't know how to do a proper install
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