Geek On The Hill

First Real-World Test of my A-iPower SUA12000E Generator

As my readers (both of them) know, a couple of years ago I purchased an A-iPower SUA12000E portable generator and wired it into my home’s electrical system to power the whole house during power outages.

I chose a portable generator rather than a permanent standby for two reasons. The first was because it’s much less expensive. The second was because I wanted to be able to use the generator should I need power elsewhere on the property (for example, to power an electric chainsaw or log splitter.

The trade-off is that using a portable generator to provide backup power to the house requires that that the cord be plugged in, the generator started, and the safety interlock switched over whenever there’s a power failure. It doesn’t kick in automatically like, for example, a Generac whole-house standby generator would. That works for me, though. I live and work at home so I’m usually here anyway, and it only takes a few minutes to connect and start the portable generator. My computers and sensitive electronics also have their own UPS battery backups.

I wired my portable generator into my home’s electrical system in accordance with the NFPA National Electrical Code, using a generator safety interlock in the distribution panel, a 50-amp two-pole circuit breaker for the backfeed, 6-gauge NM-B wire on the interior portions, and 6-gauge THWN in PVC conduit branched off a dedicated junction box for the exterior wiring and the adjacent interior wiring. I also installed a 50-amp generator inlet box on the outside of my home, which connects the generator to the house using a 50-amp generator cord.

Here are a few pictures of my wiring job.

Open electrical junction box revealing the connections between the interior NM-B wiring and the exterior THWN wiring in the author's DIY generator installation

Open electrical distribution panel showing the generator safety interlock and the backfeed circuit breaker and wiring

Portable generator in the grass outside the author's home and connected to the house using a generator cable

I must have done a really good job because not only is my wiring pretty, but for almost two years after installing the generator, we didn’t have a power failure. My neighbors were very grateful about that because apparently I’d purchased a magic generator that not only could power the entire house during power failures, but actually prevented power failures from happening at all.

Because power failures had been so frequent prior to my buying my magic generator, I kept the tank filled with fuel that I stabilized using the marine flavor of STA-BIL, and dutifully started it and let it run for 10 or 15 minutes at the beginning of every month to prevent it from getting lazy. But because it was a magic generator, we didn’t have any actual power failures (at least not when I was home), so the generator never had a chance to prove itself.

All that ended last night when the magic wore off. I was over at my friend Pete’s house on the next hill when the power went out, upon which I gleefully excused myself and drove home to my hill to fire up my generator.

The generator was happy to have a chance to prove itself and was impatiently and eagerly awaiting my arrival. I rolled it out of its shed, connected the cord to the inlet box, and hit the electric start. It immediately fired up and told me to get my butt to the basement to switch the interlock to generator power, which of course I did. One never argues with a magic generator, after all.

I switched the power over to generator, and for the next eight hours, the generator powered my whole house, using about three-quarters of a tank of gas (about five gallons or 19 liters) to do it.

For the first hour or so, the generator was powering the central air-conditioning, the well pump, the refrigerator and chest freezer, and the various lights (almost all of which use LED light bulbs). I then switched off the central air and cooked a meal on the electric range. A few hours later, when I went to bed, I turned on the portable air conditioner in the upstairs bedroom. It ran all night, keeping me comfortably cool until I woke up.

I was very happy, and my generator was very proud.

One thing I should mention is that just because the generator is wired through the distribution panel in such a way that it can provide power to all the circuits in the house, that doesn’t mean it can power everything in the house at the same time. If I tried to use too many high-draw appliances at the same time, I would have tripped either the generator’s built-in circuit breaker or the backfeed breaker in the panel. That’s not a flaw. It’s just math. The generator I chose can put out 9,000 watts constant draw and 12,000 watts peak draw, and I have to keep my electric usage within those limits.

For example, the generator can power high-draw appliances like the air-conditioning, the electric range, or the electric clothes dryer — but not at the same time. That’s why I turned off the central air when I wanted to use the electric range. Wiring the generator through the distribution panel is a simple, inexpensive approach to whole-house backup power, but it does require some discretion and common sense.

The other thing I should mention is that when high-draw devices like the well pump kicked in, the uninterruptible power supplies protecting my computers and electronic equipment did kick in momentarily due to the brief undervoltage while the generator caught up to the sudden demand. That’s also okay. That’s what the UPS’s are there for.

In fairness, I have the UPS’s set to high sensitivity; so they occasionally kick in for a few seconds even when the house in on utility power. That was a configuration choice that I made. It doesn’t mean that anything malfunctioned. The higher the sensitivity, the more often the UPS’s will kick in. That’s what they’re supposed to do, and they did it well.

In summary, I’m a pretty happy camper. In return for about five gallons of gas, I didn’t have to sit around hungry, sweating, and in the dark for eight hours. The generator and UPS’s performed admirably. The only change I may make is to buy or build a generator tent to protect the generator from the rain and deaden the noise a bit.

Richard

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