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 (4).png
--
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