We don't have #10/2 Romex on the trucks usually. It's most convenient to run #14 or #12 to a light fixture usually (if not running it in conduit). And some fixtures are not very friendly with a larger wire or cables.
I can't think of any logical reason that a lower rated breaker would be a problem. I truly think they just didn't think it through very well when writing the documentation. The lack of 25, 35, and 45A breakers is a prime example. Surely these are okay, right? Jason Szumlanski Principal Solar Designer | Florida Solar Design Group NABCEP Certified Solar Professional (PVIP) Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208 On Fri, Jul 24, 2026 at 1:00 PM Christopher Warfel via RE-wrenches < [email protected]> wrote: > Would it make sense just to upsize the conductor for this short run? > On 7/24/2026 5:47 AM, Jason Szumlanski via RE-wrenches wrote: > > My read: EG4 likely omitted 15A and 20A because these are contemplated as > high-current smart load or AC-coupled inverter ports, not branch circuit > protection for small loads. The GridBOSS is sized for things like EV > chargers, HVAC, water heaters – not standard household receptables and > lighting. They expect those to be regular backup loads. The biggest > example I have to support the need to shed a 20A load is a pool pump. > > Anyway, when I use a GridBOSS for an off-grid installation, I almost > always use Port 4 for a 15A multiwire branch circuit to support a > convenience outlet and lighting for the area on one leg and a generator > battery charging circuit on the other leg. I see no issue with it. > > One thing that supports my theory that the breaker ratings are the maximum > supported per port is that the ratings in the table overlap. Looking at > the table, on line 1, port 1 supports 90-125A breakers, then the table > goes on to support 30-80A breakers for port 1. The whole tables is a > confusing mess. And what about 35A breakers? 45A? These are common for some > mini-split units. They are not in the table, but surely would not be a > problem. > > EG4 needs to revamp this table for clarity. > > P.S. I have started using Port 1 as the main load port for smaller > off-grid jobs without even using the 200A backup load port. I just set port > 1 to operate 24 hours a day. This way, you don't need additional > overcurrent protection from an external main breaker. The downside is that > the manual bypass becomes non-functional, but otherwise it has worked out > well for me. > > > Jason Szumlanski > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida State Certified Solar Contractor CVC56956 > Florida Certified Electrical Contractor EC13013208 > > > > > On Thu, Jul 23, 2026 at 9:24 PM Dave Tedeyan via RE-wrenches < > [email protected]> wrote: > >> Hi All, >> >> I will soon be installing one of these in a detached shed, where it would >> be useful to have a light installed. There will be no panel in there other >> than the GridBOSS, inverters and batteries. The manual says that the >> smallest breaker size that is supported is a 30a breaker. See table below. >> >> I emailed their tech support to ask if there would be a problem with a >> 20a breaker. They gave a very basic answer pointing me back to this same >> table, and then recommended to add a subpanel, and then run a 20A circuit >> from there. That seems a bit overkill for a light. I cannot see why if a >> 30A breaker is allowed, a 20A breaker would not be allowed. It is just a >> simple Eaton breaker. Am I missing something here? >> >> Cheers, >> Dave >> >> [image: image (4).png] >> >> -- >> >> >> Dave Tedeyan, P.E. >> Owner | Sungineer Solar >> p: he | him | his >> a: 1653 Slaterville Rd. | Ithaca, NY 14850 >> w: www.sungineersolar.com <http://www.sungineersolar.com/> >> c: (607) 270-0370 >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> >> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & > settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other:https://www.mail-archive.com/[email protected]/http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette:http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios:http://www.members.re-wrenches.org > > -- > Christopher Warfel, PE > ENTECH Engineering, Inc. > PO Box 871, Block Island, RI 02807 > (401) 447-5773 > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
