Home Generators- Information

[FC]

http://www.backwoodshome.com/articles/thomsen28.html

 

http://www.smps.us/home-generators.html

[Dr.Hess]

Tony,

I just finished my generator installation. I built a generator shack for it out next to the power pole. It is actually the brick shiite house of generator shacks. There's 6 yards of concrete in the slab and sidewalk to it, and the siding/roof is metal. The shack itself is 4x6', and I hate to consider my cost per square foot, but I kinda went overboard on it. Dr.Linda says it's the nicest outhouse in Arkansas. The whole house transfer switch is mounted inside on the back wall. I got the 200 amp transfer switch from Harbor Freight and used a 20% off coupon. It is not chinese. My generator is a 7KW load, 8.75KW "start" or whatever, Honduh powered unit I got from Sams for one large. I hope to be able to run one heat pump and one hot water heater (though not necessarily at the same time) plus lights, stove, etc. It will probably be like Green Acres where you switch on a 5 and a 7 and don't go over some number, etc., but we're all electric, and sitting in the dark for a week in an ice storm gets one thinking about how not to do that again. I also poured a small 3x4' concrete pad under the porch for batteries. I'm going to put a couple of lead acid batteries on it in plastic boxes and run an inverter off of that. I bought an inverter during the last ice storm the day before power came back. I can hard wire that to a couple of batteries in parallel and run Romex from that up inside the house to one outlet so we can charge phones, computers, LED or other light, maybe run a TV or radio, etc. when the generator is off at night, then recharge the batteries during the day with the generator on. I haven't started on the battery aspect yet, besides having the pad now and the 1.5KW inverter and thinking. I'll probably have to build a charger/charge controller from scratch because the store-bought ones are really expensive.

[roscoedoh]

Doc,

 

I'm not sure what genset you're running or how you've got it hooked up, but...

 

if you've got two 120V circuits coming out of your generator, take that 7kW and divide it by 240. It should put roughly 29 amps at full load and roughly 36 amps at start up/surge output. That should be plenty to run lights and a microwave and the motor and thermostat of a gas fired home heating unit. I do not think it'll touch an A/C compressor or the emergency heat strip in a heat pump. I think it might have a hard time powering an electric water heater with it as well I know mine draws at least 30A by itself. Also, I would not connect any delicate electronics up to it (e.g. computers, stereos, etc.). While every generator manufacturer I've dealt with at work swears up and down that they've made huge advances in isosynchronous alternator designs...I just don't trust them that well. Maybe with a quality voltage-regulating UPS system between your computer and the generator; maybe.

 

 

 

I deal with generators a lot at work so here's some random thoughts on them:

 

-Always buy more than you think you'll need. Its better to run your generator at 70% capacity and have current to spare than it will be to max out what you're already planning for. Wiggle room is a good thing and a machine that doesn't work at WOT 100% of the time will have a longer service life.

 

-If you can spend the money, buy a generator that spins at 1800rpm over any 3600rpm unit. They're inheritely quieter and last longer. (Heavy on QUIET!)

 

-When you wire it up, avoid back-feeding or piggy-backing any two pole breakers. Go ahead and run a dedicated breaker to your panel. Its much safer and less likely to cause a fire.

 

-Remember that all motor loads (any kind of compressor or fan) will have an in-rush current and you'll need to take that into consideration when you're looking at surge output on your genny.

 

-Use Stabil in your gas.

 

 

 

Lastly, here's a couple handy links courtesy of my friends at Eaton Electrical:

 

Generator Sizing Chart

 

Standby Generator Systems Wattage Worksheet

[Dr.Hess]

Thanks for the comments. This is the transfer switch I'm using:

http://www.harborfreight.com/200-amp-generator-manual-transfer-switch-42163.html

There's no chance of back feeding.

 

Yeah, 30 amps. I think my generator will run one water heater. It might run my upstairs heat pump, without the electric backup heat, of course. All my electronics from the computers to the TV are on UPS'. It's the only way I can get anything to last.

[roscoedoh]

Quality equipment Doc. That ought to have you covered all the way up to 48kW!

 

What brand of UPS are you running? I live out towards the end of the line and have seperate UPS's for the home stereo and computer systems on the list. I'm also planning on wiring up a whole house surge module in the loadcenter sooner or later too.

[Dr.Hess]

Yeah, that's a good xfer switch. I got it with a 15 or 20% off coupon when it was on sale, so my cost on it was around two hundred, I think. It wouldn't fit in my Esprit, so I had to come back with the Truck. Also wouldn't fit under the house where I wanted to mount it, so I built the brick shiite house of generator shacks out by the pole.

 

I just use APC brand 500W UPC's now. I salvage them when they are thrown away with dead batteries and put a new battery in. I have a couple of 1KW rack mountable industrial UPC's from Ma Bell that I bought on eBay years ago for $40 each (no batts). One stopped "resetting" after a power glitch and I'd have to shut it off and restart it, so I retired that one and used the other. It would run my whole network for over a half hour when the power went down. I got tired of buying 4 new batteries for them every couple years and just went with the APC's and stick one on each computer: one for my desktop, printer and the netbook internet server, one for Dr.L's laptop and printer/scanner, one for the stereo/tv/dvd/PC for DivX , one in the shop for my shop desktop. They'll only give me about 5 minutes of power, but that's enough to shut down.

[FC]

I'm a babe in the woods on this. The better compressors are diesel, and cost a bunch. The transfer switch- did you hook it up? Easy?