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  1. #1

    Default 10KW Standby Generator for home w/ 200A service - Service entrance & load shedding

    I'm doing my own Generac install and am comfortable with all the install work - LPG is done and waiting for inspection - (hired a local LPG company to check my work first). Now on to the electrical, which I thought I was more familiar with, but could use some validation - or correction on my plan.

    Home has UG feed to meter on exterior of block garage wall. meter feeds through wall to panel inside garage. Panel obviously has 200A main breaker at bottom.

    Genset came with a 100A Generac Auto-Xfer switch, which I swapped out with a 200A non-service rated unit. Has 4 24V load-shed capability intended for A/C units.

    1st thought:
    I would purchase a 200A panel box to mount next to the original service panel and feed it from the meter - making this the new service disconnect device. From the load side of the new disconnect breaker I intend to supply the Xfer switch utility side. Again, obviously would connect the generator output to the generator side input of the ATS.

    The 10K generator is really only suitable for part of the full home load - bringing me to my

    Second thought:
    The ATS has load shed capability for 4 A/C units.House only has one. In SW FL, A/C and refrigerator are priorities, so I don't really want to shed them. AC draws about 18A w/o heat - which is never used and breaker for coils is kept off. Could I simply add an appropriately rated box with DP breakers with 24V coils to shed the 3 largest non A/C loads, or do I need to bu the fancy, overpriced CMM frequency-sensing modules from Generac to shed them? I am talking about water heater, range, electric heat, etc.

    Local licensed Electrician wanted to add a second panel box - having one for the generator feed and the other for the utility feeds to split the loads accordingly by moving some breakers to the new panel box. It seems the cost of materials is similar, however I can't get my head around 2 issues with this method - 1) Neutrals and 2) What would be considered the service disconnect?

    So, which is the better method? If my concept is not to code, please let me know also.

    Any thoughts will be greatly appreciated.

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  2. #2
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    Default Re: 10KW Standby Generator for home w/ 200A service - Service entrance & load sheddin

    Quote Originally Posted by Christopher Loiacono View Post
    LPG is done and waiting for inspection - (hired a local LPG company to check my work first). Now on to the electrical, which I thought I was more familiar with, but could use some validation - or correction on my plan.
    Acting as owner builder under the owner builder exemption to licensing (from your introductory post), and being as you did the above, I recommend hiring a electrical contractor to review your install and make recommendations - nothing better than talking with someone who is actually looking at what you both are talking about.

    That would be money well spent, as it was with the Plumber/Mechanical/Gas contractor for the gas piping system.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3

    Default Re: 10KW Standby Generator for home w/ 200A service - Service entrance & load sheddin

    Thank you Jerry. I have an an EC on my permit as a sub for me - but he's quoted me a ridiculous price. It would be awkward to ask him again... I've given him a lot of commercial business over the years, and believe the price he gave me means he doesn't want the job. I suppose I could contact the EC the gas piping company subs their generator electrical to and ask.

    I've done similar wiring designs in scores of industrial applications - and can understand the NEC - just don't know how this would fare under residential. Would it even raise any flags in the AHJ's inspector's mind?

    Clearly, someone must have seen this type of arrangement before...


    Quote Originally Posted by Jerry Peck View Post
    Acting as owner builder under the owner builder exemption to licensing (from your introductory post), and being as you did the above, I recommend hiring a electrical contractor to review your install and make recommendations - nothing better than talking with someone who is actually looking at what you both are talking about.

    That would be money well spent, as it was with the Plumber/Mechanical/Gas contractor for the gas piping system.



  4. #4
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    Default Re: 10KW Standby Generator for home w/ 200A service - Service entrance & load sheddin

    Quote Originally Posted by Christopher Loiacono View Post
    Thank you Jerry. I have an an EC on my permit as a sub for me ...
    If he is on your permit, that means that he, not you, is the electrical contractor on the job.

    I would clarify with him what he says or wants to do, but if you are going to do the work, he should, for his benefit as much (or more) that for your benefit, either 'do the work', 'inspect your work', or 'remove his name from the permit'.

    In many jurisdictions, only the contractor on the permit is permitted to call for inspections as only the contractor on the permit is the responsible party for the work, in your case, that would be the electrical contractor.

    The first advice I would give is to install an ATS which is rated the same or higher than the service it is switching from/to, and that the ATS be 'Suitable for use as Service Equipment' rated.

    While the ATS may be switching "off" with no load (the utility power is "off"), switching back "on" occurs when there is utility power, and thus the ATS should be rated for what it is switching "on" ... your 200 amp service.

    ~~~~~~

    Added with edit:

    Additionally, when manually switching the ATS "off", you are doing so under load, and the switch needs to be rated for the same or higher rating as the service it is switching "off", as well as switching "on".

    Last edited by Jerry Peck; 06-14-2018 at 02:41 PM. Reason: Added an additional aspect
    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5

    Default Re: 10KW Standby Generator for home w/ 200A service - Service entrance & load sheddin

    Quote Originally Posted by Jerry Peck View Post
    If he is on your permit, that means that he, not you, is the electrical contractor on the job.

    I would clarify with him what he says or wants to do, but if you are going to do the work, he should, for his benefit as much (or more) that for your benefit, either 'do the work', 'inspect your work', or 'remove his name from the permit'.

    In many jurisdictions, only the contractor on the permit is permitted to call for inspections as only the contractor on the permit is the responsible party for the work, in your case, that would be the electrical contractor.

    Yes, that is certainly the case here.


    The first advice I would give is to install an ATS which is rated the same or higher than the service it is switching from/to,

    I just purchased an ATS to = the 200A service of the original panel, as I thought I mentioned.

    and that the ATS be 'Suitable for use as Service Equipment' rated.

    Unfortunately, it's not a Service Entrance Rated ATS. The cost difference of the SER ATS is 3x the cost of adding a 2nd panel box with a 200A main to serve as the service entrance. The amount of work to position the ATS on the inside of the CB wall behind the meter would also be much greater. All the branch circuit wires would likely be too short to move the original panel box more than a few inches.

    It's late Friday afternoon, so I'll call the EC Monday. Thanks gain.


    While the ATS may be switching "off" with no load (the utility power is "off"), switching back "on" occurs when there is utility power, and thus the ATS should be rated for what it is switching "on" ... your 200 amp service.

    ~~~~~~

    Added with edit:

    Additionally, when manually switching the ATS "off", you are doing so under load, and the switch needs to be rated for the same or higher rating as the service it is switching "off", as well as switching "on".
    $.02 more....As an EE, I get this stuff. As a non-licensed electrician, this code stuff can be confusing and seems to be left to AHJ inspector's and contractor's preferences.


  6. #6
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    Default Re: 10KW Standby Generator for home w/ 200A service - Service entrance & load sheddin

    Quote Originally Posted by Christopher Loiacono View Post
    ... this code stuff can be confusing and seems to be left to AHJ inspector's and contractor's preferences.
    Yes, the code stuff can be confusing, and, unfortunately, yes, some AHJ do what they want - and not just for electrical, for all trades ... but ... many also understand what needs to be done and understand the codes.

    In Florida, a lot depends on if the AHJ is rural or urban - with urban departments having more current training and more current knowledge of things, whereas rural areas don't, partially because rural areas simply don't have much of that stuff installed, so no one learns about it.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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