Electrical inspection and new off-grid cabin build

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  • Riley5781
    Member
    • Dec 2015
    • 98

    Electrical inspection and new off-grid cabin build

    Here's an interesting development on my off-grid cabin build.
    My cabin is at the electrical rough in stage and the electrical contractor has determined from my maximum loads and other factors (likely the smallest panel possible) that I need a 30 amp service. He asked about the size of my generator and we responded that it's a 5KW gen-set.

    He's now worried that the electrical inspector will fail us because my generator is under sized for my panel. At 30amps, I would need a 7200 watt generator.

    Now I have designed my cabin and loads to be very frugal so I doubt I could ever draw 30amps.
    I understand why the code is written this way but it doesn't make a lot of sense for an off-grid cabin.

    My solution is to point out that on my XW6048 inverter, I can run in Generator Support mode which combines the output of my battery bank (6KW) and my generator (5KW) for a total of 11KW.
    That's more than enough.

    I just thought I'd post this situation in case of others have run into this challenge before??.
  • Mike90250
    Moderator
    • May 2009
    • 16020

    #2
    Is the generator hardwired in, or via a twist-loc cable connector ? if a connector, the inspector shouldn't even care.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment

    • Riley5781
      Member
      • Dec 2015
      • 98

      #3
      Good question Mike, we haven't gotten that far yet as the generator isn't wired in or even on site yet...
      The Electrical contractor asked the question of my contractor and my contractor replied that it's a 5KW genset (Onan CCK 5KW).

      Sounds like I like I should wire with a twist-loc but I suspect the inspector will still care but at least it gives me options.

      Comment

      • inetdog
        Super Moderator
        • May 2012
        • 9909

        #4
        Originally posted by Riley5781
        Good question Mike, we haven't gotten that far yet as the generator isn't wired in or even on site yet...
        The Electrical contractor asked the question of my contractor and my contractor replied that it's a 5KW genset (Onan CCK 5KW).

        Sounds like I like I should wire with a twist-loc but I suspect the inspector will still care but at least it gives me options.
        What the NEC says, which is all that the inspector should be concerned about, is this:

        1. If you have a manual transfer switch (or interlocked main and backfeed breakers that must be manually moved to switch from grid to generator backup, no problem.
        2. If you have an automatic transfer switch that will try to start and cut in the generator on grid power loss, either the generator must be sized to cover the full expected worst case load or there must be automatic load shedding relays.
        3. If the generator is the sole power source, then the NEC does not care about its size. There is a rule that utility service must be sized to meet the calculated load, but there is no such provision for a generator in an off-grid situation. There should be a breaker on the generator to protect it from overload. The backfeed or main breaker in the panel does not have that responsibility.

        You can confirm this with the electrical inspector if you want.
        SunnyBoy 3000 US, 18 BP Solar 175B panels.

        Comment

        • Mike90250
          Moderator
          • May 2009
          • 16020

          #5
          Tell the electrician you are installing a 20Kw Genset on some rated outlet (like an RV plug). That way, the cables will be large enough to handle one, if you ever need to expand. (or whatever size you feel is "right")
          Have it feed a 50A sub panel, that has your critical loads, fridge, furnace, water & sewage & sump pumps, garage door opener, gas range (gas ignitors), heat tape, couple of outlets to recharge stuff with, some overhead lights and the Iron Lung for Grandma.
          Then, when you need, you can power those loads, If you use a smaller genset at first, you may need a balance transformer to get 240V from the 120V of a small genset,

          And pour a pad for the genset, with a "dam" to contain any spills. EPA has suggestions for that.
          Last edited by Mike90250; 10-06-2016, 03:08 AM.
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment

          • Riley5781
            Member
            • Dec 2015
            • 98

            #6
            Originally posted by inetdog
            What the NEC says, which is all that the inspector should be concerned about, is this:

            ... snip ...
            3. If the generator is the sole power source, then the NEC does not care about its size. There is a rule that utility service must be sized to meet the calculated load, but there is no such provision for a generator in an off-grid situation. There should be a breaker on the generator to protect it from overload. The backfeed or main breaker in the panel does not have that responsibility.

            You can confirm this with the electrical inspector if you want.
            I am off grid so #3 applies to me.
            I am going to work the angle that generator support (load share) from my inverter meets the requirements needs. I suspect most of these guys experience is around generator back-up scenerios and have never really dealt with off-grid.

            It will be interesting to see how this goes but thanks for info on the NEC and hopefully I won't need to have that discussion.

            Comment

            • maple flats
              Solar Fanatic
              • Oct 2011
              • 108

              #7
              Since you are in BC Canada, you need to find what the code there is. In my area of New York State, off grid has no electrical inspection. Here the code only comes into play when you have a connection to the grid. My off grid system at my camp needed no inspection, my grid tied system at my sugarhouse did need one.
              6,32 KW solar, net metered, maple syrup producer.

              Comment


              • ButchDeal
                ButchDeal commented
                Editing a comment
                Off grid still needs inspections. It is based on occupancy permits. Your off grid structure just doesnt have an occupancy permit. Also required for insurance but likely you don't have it insured either.
                Grid tie needs electric inspections as well as interconnect.
            • maple flats
              Solar Fanatic
              • Oct 2011
              • 108

              #8
              Sorry to differ, but my off grid structure does have an occupancy permit. The codes inspector just told me there is no electrical nor building inspection required if the system is not tied to the grid.
              6,32 KW solar, net metered, maple syrup producer.

              Comment

              • ButchDeal
                Solar Fanatic
                • Apr 2014
                • 3802

                #9
                Originally posted by maple flats
                Sorry to differ, but my off grid structure does have an occupancy permit. The codes inspector just told me there is no electrical nor building inspection required if the system is not tied to the grid.
                There are remote locations were building codes are not inforsed but to get a CO ( certificate of Occupancy ) the county is supposed to insure that a permit and building codes were followed which means inspections.
                There are size limits for CO ( the reason behind the small home craze) but the size limit varries and is generally quite small in towns ( reason micro houses are on wheels) .

                So does your off grid home have a CO and no permits?
                Last edited by ButchDeal; 10-08-2016, 07:15 PM.
                OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                Comment

                • J.P.M.
                  Solar Fanatic
                  • Aug 2013
                  • 14942

                  #10
                  Originally posted by ButchDeal

                  There are remote locations were building codes are not informed but to get a CO ( certificate of Occupancy ) the county is supposed to insure that a permit and building codes were followed which means inspections.
                  There are size limits for CO ( the reason behind the small home craze) but the size limit varries and is generally quite small in towns ( reason micro houses are on wheels) .

                  So does your off grid home have a CO and no permits?
                  FWIW, having lived in NYS for about 2/3 of my life, I've have no problem believing that unusual or seemingly inconsistent practices exist with respect to permitting, particularly in upstate counties, but I'd still confirm.

                  Comment

                  • maple flats
                    Solar Fanatic
                    • Oct 2011
                    • 108

                    #11
                    Big change. After talking to the codes guy and being told my system did not need a permit and inspection, he sent me a letter yesterday. I now need both. He said he had made a mistake. So I now need to jump thru all the hoops too. I just love it when the codes officer told me it was not needed and then he sent the letter saying that I had to have one and that I could be fined $100 for starting the work without a permit. My guess is that his boss (whoever) yelled at him and he now has to show his authority. He did say today that I can just take pictures and make diagrams from those.
                    6,32 KW solar, net metered, maple syrup producer.

                    Comment

                    • J.P.M.
                      Solar Fanatic
                      • Aug 2013
                      • 14942

                      #12
                      Originally posted by maple flats
                      Big change. After talking to the codes guy and being told my system did not need a permit and inspection, he sent me a letter yesterday. I now need both. He said he had made a mistake. So I now need to jump thru all the hoops too. I just love it when the codes officer told me it was not needed and then he sent the letter saying that I had to have one and that I could be fined $100 for starting the work without a permit. My guess is that his boss (whoever) yelled at him and he now has to show his authority. He did say today that I can just take pictures and make diagrams from those.
                      Not rubbing it in, but per my 10/08/ 1:26 P.M. post, I'm not surprised.

                      Comment

                      • Riley5781
                        Member
                        • Dec 2015
                        • 98

                        #13
                        My solar install with be done with a permit...

                        Comment

                        • maple flats
                          Solar Fanatic
                          • Oct 2011
                          • 108

                          #14
                          Mine would have been done with a permit had the codes officer given me the accurate info. I went in to get one before the install began but he stated that no permit was required because it is totally off grid. After it was installed, he "changed his mind".
                          Now I'm getting all the info for the permit application. He did say that he will not impose the fine mentioned in the letter because he had made the error when I went the first time to get the permit.
                          6,32 KW solar, net metered, maple syrup producer.

                          Comment

                          • raegangibb
                            Junior Member
                            • Jun 2017
                            • 1

                            #15
                            inetdog - I know this is an old thread, but I'm curious about your #3 at the top. I'm in British Columbia with no hydro access (it will be decades before it ever gets close) and am being told by an inspector (who does not seem very knowledgeable on off-grid) that my "portable" generator needs to be sized to my calculated load, not the actual load. In my case that is about 13kw vs an actual load of maybe 15 8w LED lights and a TV (worst case 1000w). My hope was just to install a 30 or 50 amp plug on the outside of the house and wheel up my 7200w generator when we are there and plug it in feeding the main panel. The main panel of course would be properly sized based on the calculated load.

                            My medium to long term plan is to instead feed the panel with a solar setup, but that just isn't in the budget right now. I'd like to get occupancy with portable generator only and deal with permits/inspections for solar when I can afford it. Any backup you have on your #3 from the NEC might be helpful in me convincing the inspector I don't need to buy a massive gen-set.

                            Comment

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