ECN Forum Forums General Topics of the Trade General Discussion Area Sizeing a whole house generator

Load calcs are always a compromise between what is usually on and what might be on. My house calculated out to around 180a using the optional method and over 200 with the standard method but since I have never had a $5000 electric bill it is clear all that stuff is not on very much.

Thanx all! Back to Earth I land.
You'r all correct. just a passing thought I guess. My 5.5KW worked fine this past storm,6 days, Microw,220 well,heat lights TV etc. (no cable but the old CDs got a bit of needed use). Looking back, Brought us back into perspective.
Warmth,warm showers and the like.
Conclusion: 8KW in the future,to take the load of the well better. (2k+ sqft). To fix my house as described, would essentialy equate to a service change (reorg.ckts and sub panels etc.)
However, It will be nice to know for future clients.
Thanx for the replies!

One detail I forgot to mention - shame on me! - is noise.

Short version: Get the optional 'sound package.' Then, still put the genny in a shed, and surround it with shrubs. Do everything you can to eliminate the roar of a generator. The 'standard' mufflers are simply a joke.

Ya, the Honda I use now is OK, My Coleman... Wow that is obnoxious!!!
I heard a LNG one the other day at a telco site, about 20KW, could barely hear it at 20 yards!

Sounds like you have pretty much the same setup as I do. That being, a 7200W, 10-circuit generator panel with 1-DP handle tie for the 240V well jet pump. I also tied in the microwave, oil burner, refrigerator, some kitchen counter receptacles, two bedrooms, bath lights, office and basement lights. No electric range though, but the Weber gas grill is always on the back deck. Of course, I can’t run everything at once, but this seems adequate for emergency use. I think I’ve only really needed it once in the 5-years since I put it in, but it’s a good feeling knowing that it there.
Right now I only have a 3700W Coleman with a little Suzuki engine. It sips gas and is pretty quite, but I was actually was thinking of going up to 4400W or so.
With most portable generators, I don’t know if you ever really get away from that initial brownout, voltage sag when the water pump or other motor load starts, like the refrigerator compressor.

I use the old Honda EM5000s. Nice little unit. Set up is the same,Only I need to tweek the chosen ckts. Looked ok, but after the 6 day outage,found a few flaws. no Kitchen rec. pleanty of light.

I can run every light, TV, computer, refrigerator, etc, in my house with my 3500W (15A 240V) gen. It can also run our microwave, coffee pot and garage doors, although I've always been careful not to do any of these simultanously. I can even run our range, though the lights blink every time the heating element kicks on. I think it *might* handle one of the 3 ton heat pumps, but I haven't been desperate enough to try it out yet. I'm just happy to have lights and all.

That said, you have to be careful of the small cheap generators; they're not regulated very well, and can put out excessive voltages if they're sized too large/loaded too lightly. The first time I used mine, I had to run around and turn on every light in the house to load mine down to 125V. Fully loaded (like when my stove is on), it's down to 110V. It's a common problem.

I am doing a little energy audit today and my house cruises at 9a on one phase and 3.1 on the other.
That is with the pool pump and spa (low speed circulation) pump running.
In the house there were a couple lights on, TV, a whole house fan on low, this PC, and all the stuff that never turns off.
The 36" S/S fridge wasn't running but it adds 2a when it is (I have 2)
The rub starts when I turn on the range, the water heater kicks on and the AC is running.

I often enjoy this subject since I went to a great amount of trouble to set my house up with a generator that now hardly ever gets used. When I first moved into my house, power outages were very lengthy and frequent, and with a house full of boys, the toilets became a huge problem since we are on well water. I was also surprised how low my total load was as well.

I installed a 100 amp sub panel with interlocked main breakers. In that panel, I managed to put the range, water pump, sewage ejector pump, sump pump, microwave, freezer, three refrigerators and almost all lighting and GPA circuits. I'm using a 5,500 watt generator and it does surprisingly well. True, it coughs pretty hard when we first throw the transfer switch, but I get around that by turning off all branch breakers first, transferring, then turning them on one at a time. I installed this sub panel in my garage since the main panel is at the opposite end of the house in the basement. Through some trickery in backfeeding or refeeding existing circuits, it worked out well. I also put an emergency light set in the garage so that we can see what we are doing in total darkness.

Although I am currently only using a 5,500, I still used a 60 amp generator main in the panel. That way, when I win the lottery, I can buy a larger generator and only have to change the inlet and cord set. If that happens, I might even belly up for an ATS.

Surprisingly, we run pretty comfortably with this setup. I'm a bit cocky, so when the power goes out and I'm on generator, I make sure to turn on all of the lights. We don't go as far as trying to cook Thanksgiving dinner during an outage, but with load management, I think we could in a pinch. I don't have my heat, water heater or washer/dryer on the transfer panel. There's no way I'm coughing up the money to run the heat pump too.

After all of that, we hardly ever lose power anymore. The POCO reworked our section of the grid about ten years ago and I think I may run the generator once a year now. It's still nice to know that we have the water issues covered, both coming in and out.

In the 25 years I have lived here I would have about 4-5 days on the generator (one day at a time). Any other outages are so short my UPS keeps the TV and PCs on.
If the FPL guy who lives across the street ever moves or retires that could change I guess.
His wife tells him he can't come home to a dark house, he still has something else to finish at work.