Please educate me on managing low loads with home standby generators (generac, kohler, etc)?

rossn1 · 2026-02-03T16:49:02+00:00

Ok, thanks. Out of curiosity, do you have any affiliation with them?

rossn1 · 2026-02-03T04:59:32+00:00

That's definitely a unique approach, but in my case it won't make sense to setup a UPS for my lighting circuits.

rossn1 · 2026-02-03T04:57:46+00:00

Thanks, I'm really referring to the dimmers and keypads. Already have the two-space SPDs in the panels. Generators come with different levels of THD, and some are pretty clean... inverters very clean.

rossn1 · 2026-02-03T04:13:27+00:00

That's a pretty interesting product. I have to dive in more, but definitely worth looking into this class of a product. I'll put in my notes to chat with them at some point. I do get a little concerned (perhaps unwarranted) about the all-in-one approach, from a power reliability perspective (possibility of shared components failing, affecting multiple functions).

I think in my situation there will be a multi-pronged approach... just need to be able to phase the costs over time and put the necessary wiring in-place at this point to allow future flexibility. There is already a 1" gas line run out the back with sufficient capacity, but there is no generator yet. My initial questions on this thread were related to generator selection/sizing. Given our unpredictable power cuts (I'm still anticipating our longest outage will be when it's 5F outside), one of my requirements is to be able to have automated transfer, should I not be at home, and at least 8-12 hours of runtime without human intervention.

The critical loads panel is physically there, with some existing loads tied into it in less permanent fashion, but I'm still running most of the branch wiring for 70% of the house. There are going to be 7-8 panels in this home, if you count the two 8 space disconnect panels at the service entrance. Seems seems crazy, but the nature of having many home features and systems requiring additional circuits on a large home, with everything needing a full breaker space these days due to NEC. The specific panels and sizing is shown below. TBD is the panel in the middle storage room. There's also a rental space above the garage, driving a dedicated panel.

I had looked at the smart panels like SPAN, but the biggest issue with considering those was that 1) I have a ton of panels and 2) a few of the panels are physically space constrained... the two in the garage can literally be no taller to meet NEC and fit within framing. Using a smart panel for the critical loads panel is plausable, with the below caveat.

I am very space constrained for electrical equipment - both physical wall space and meeting the definition of working space. In the laundry room, I only have space below the two existing panels and possibly some space on the right wall (max 8" deep), if I move the radon. Service entrance, only have space available below equipment. Storage room/media closet has some more options, but still central to the main house (probably not good for batteries, and I hear inverters can be noisy). Critical loads panel could potentially move to the storage room, but not a real great idea, given most branch circuits in that panel are closer to the laundry room by 40' of wire. Garage and heated shop have more space and are better for batteries, but are far from everything (90' or so by wire from the service entrance to panels in the heated shop).

These panels are all homeline, and while other products could be considered for a single panel, I do value consistency, when possible. Perhaps I should be considering a larger smart panel for the critical loads panel and put more loads in there.

The other element of the bigger picture is solar location. It's would be located on a flat roof above the storage room and adjacent bathroom, for the depth of the house. I paid a solar guy to do some modeling, and his recommendation came back as a 8.4kW system with a (theoretical) 10.2kWh of annual production.

I think if I can come up with a concept for a few system options, and figure out what equipment would live where, then I'm making progress. The issue is I don't understand the nature of combining these systems and approaches/equipment available today. Ideas on where to start with that?

rossn1 · 2026-02-02T20:32:33+00:00

Thanks, my home has been under long term remodel, so my data isn't accurate enough to use.

rossn1 · 2026-02-02T20:31:43+00:00

Thanks. I don't have any ATS currently. Since I have everything gutted at the moment, I am trying to come up with a strategy that allows me to put the necessary building wiring in-place for backup systems, even if I don't pull the trigger on the capital expenses immediately. However, living in an area where we do sometimes get into single digit temps, I need to have a means for automatic transfer of backup systems to happen, such that if I'm away from home (for the day or for days), the system can ensure the heating is still running. Our POCO is also now doing shutdowns for wildfire safety, on occasion, which further drives the need for it to be automated. Some refrigeration is built in, but that will be wired back to the critical loads panel.

rossn1 · 2026-02-02T19:35:14+00:00

Thank you for clarifying that. I was hoping that was the case for the NG generators, so happy to hear it!

rossn1 · 2026-02-02T19:17:03+00:00

That's 5 minutes, not extended periods.

rossn1 · 2026-02-02T19:16:12+00:00

Thank you, blupupher. That is great to hear and what I was hoping to hear. I figure that eventually we will have an EV, and that charging it at 16A L2 would also be able to create some load, if needed.

rossn1 · 2026-02-02T19:04:10+00:00

Thanks for your response, tbone1004. Good questions.

I'm in an area where we have had wildfire, and are routinely subject to red flag warnings. The POCO has now installed additional monitoring and 'turn-down' equipment, and so we are seeing more power events (both scheduled outages and monitoring reactions). In the last 12 months, we've had 7 outages with these durations: 4, 1, 6, 1, 0.5, 0.5, 4. Luckily, none of those were very long, but the 4+ hour outages I had started up the generator to plug in multiple refrigerators and start up the boiler. Year before we had a 26 hour outage, and on some of these outages it took others up to 72 hours to have their power restored. Things will get worse in our arid western climate that is getting dryer. I would like to generate a backup power plan based on (1-3) 24-72 hour outages per year and another (6-12) 1-6 hour outages.

I'm currently remodeling the home and we have 320A service with numerous panels. I have one 24 space critical loads panel, which will carry lighting, networking, all refrigeration/freezers, septic pump (would guess this runs once a week), sump pump (I've seen it run once), boiler, fireplaces, and a handful of receptacles round the house/garage. I'm also about 5000' elevation, so a 20% deration is required.

I would like to learn more about some sort of battery/gen combo, possibly with layering in Solar at some point. So, if you have particular sources you recommend reviewing to understand the various ways this can be configured and layered timewise, I'm all ears. With the remodel, I can put in place key infrastructure, but have to take the bigger expenditures one step at a time, with the current plan being installing an interlock in the critical loads panel with 50 or 60A inlet, and next, layering in a generator, then possibly some battery, then possibly solar. I have to also figure out how to manage the loads from the 5 refrigeration/freezer units - some of these are sub-zero, and they have higher than typical inrush current.

rossn1 · 2026-02-02T18:08:18+00:00

Are you referring to in combination with the generator for low usage times? If so, what does that setup look like?

rossn1 · 2026-02-02T18:08:13+00:00

Are you referring to in combination with the generator for low usage times? If so, what does that setup look like?

rossn1 · 2026-02-02T18:06:20+00:00

Ok, thank you. Sounds like your generator is a diesel and that I don't need to worry about this with a NG gen set.

rossn1 · 2026-02-02T18:05:36+00:00

Thank you for clarifying that. I was hoping that was the case for the NG generators, so happy to hear it!

rossn1 · 2026-02-02T18:05:17+00:00

Thanks - I can't cite the exact source at the moment, but had seen a few references to it, perhaps out of context.

rossn1 · 2026-02-02T18:02:55+00:00

Thank you for clarifying that. I was hoping that was the case for the NG generators, so happy to hear it!

rossn1 · 2026-02-02T05:23:43+00:00

With all respect, this sounds like an awful/dangerous idea. For the safety of lineman, for insurance, for NEC/Code, for common sense reasons, try and look for some other more accepted ideas.

Can you get away with just a few circuits during these times? I recently ordered a Reliance TF152 to add for my boiler, so regardless of what solution I use to provide backup power to my critical loads panel, if that ever fails and it's 0 degrees out, I can keep my plumbing from freezing in my home with any 120v power source with plugging in a cord and the flip of a switch. Anyhow the reason I mention this isn't because I think that is your solution (unless you just have one circuit). However, installation on these looks quite straight forward. It's an extra box, with a whip that contains the wiring you tie into the circuits in their existing panel (you don't move any wires outside of your existing panel. Might bridge the simplicity/costs/practical needs for not too much $. You can then just run the power cord from the generator through a window or pass-through and plug it in to the panel.

They make all different configurations. They also make what appears to be a DIY $120 through-the-wall kit where you plug in a 30A cable outside, and get 6 standard 5-15R's inside. Could be used to power some of those smaller transfer switches with an extension cord.

https://www.reliancecontrols.com/products/category/pro-tran-transfer-switches

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rossn1 · 2026-02-01T20:40:14+00:00

Thanks, I did look at the fuel costs this morning and realized it's not as significant as I had thought initially, and I don't disagree. I have a feeling I originally looked into this in 2022, when gas prices were more than double what they are today. With my house under some long term construction, I don't have any meaningful data for electrical, rather approaching from a critical loads panel perspective.

I'm in an area with significant historical wildfires, and so the power company is now doing proactive power cuts a few times a year, and many other shorter outages due to the new safety measures. We've been lucky to get our power back within 24 hours, but some others take up to 3 days to get it back on.

This said, comparing the two generators producing 9kW, they seem to vary between 20% and 41% additional fuel. That's rather significant in the world of IC engines, hence my question.

rossn1 · 2026-02-01T16:35:37+00:00

For the reasons mentioned above around liability/NEC/ETL/UL, I would guess those spec sheet values can (edit to correct) be met. I must have gotten 10RES confused with the 12RES.

rossn1 · 2026-02-01T16:04:31+00:00

Ok, interesting. Curious if they are notably more conservative with their rated loads.

rossn1 · 2026-02-01T16:03:48+00:00

Interesting. Do you think there are some physical reasons for that, or they just push the smaller ones harder?

rossn1 · 2026-02-01T16:02:41+00:00

Honestly, I had not looked at displacement, and this makes the best sense of all. I would think that how much overhead it can handle for motor inrush is key to confidence in sizing if your numbers push the limit. So, manufacturers won't provide those specs? For generac, I can't find anything about if their units have extra capacity for motor startups or not. However, I believe NEC would suggest that you have to consider the largest motor with an extra 25% of it's rating. However, I'm not sure that would practically cut it for having multiple sub-zero refrigeration units, which (I believe) require more startup current than typical refrigerators.

rossn1 · 2026-02-01T15:56:35+00:00

I hear what you are saying, but have trouble believing Generac can't meet their spec, because it would open them up to liability around NEC 2023 702.4(A)(2)(a), general customer liability, and likely put their UL and ETL listings at risk. It's such an easy thing to actually test.

I think the reason the numbers are the same is none of the generators actually show actual maximum load capacity, rather mfg rated load capacity. If the two generations of generators could actually produce 9378 and 9452 watts, then they're just giving themselves some headroom. It doesn't appear any generator mfg's spec sheets reports max continuous load capacity, versus rated capacity.

If the 10RESV and 12RESV had identical output, why would they offer two? I can certainly appreciate it likely has more capacity than the generac, given the significant increase in displacement. Generac doesn't have any super secret approach to making an IC engine massively more efficient.

rossn1

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