12/13/12 4:24 PM

Thinking of getting one for my son whose house is prone to power loss whenever trees take down wires in his neighborhood. What should I be looking for in a portable generator??

12/13/12 4:42 PM

Seriously

12/13/12 4:42 PM

Bigger than you think. Unless all you want to do is keep a few lightbulbs on, a generator has to power some pretty high wattage appliances so size it accordingly.

If the house has natural gas service, get a generator that will run on it. Gas service is very, very rarely interrupted and the generator can run indefrinitely on it. If he doesn't have natural gas service, get a propane powered generator and a BIG propane cylinder. The least desirable fuel is gasoline due to it's storage danger and the fact that it isn't stable over time and, even treated with stabilizer, has limited shelf life.

Finally, have the generator installed by an electrician. You don't just run extension cords, you need to have it properly wired into the house's main breaker box with the appropriate switches.

12/13/12 4:51 PM

Most obviously, what capacity? Are you going to power the house or just a couple of crucial items, like the furnace and fridge?

The big advantage of powering just a few select devices is that you can go smaller/cheaper and simply plug extension cords into the safely located (CO and all that) generator. A larger one to power the house will require having an electrical cutover switch installed on the main power in-feed.

Bigger ones also use gas at a greater rate than you might anticipate. You can't assume that local gas stations will be operating. That means storing many gallons of treated gas somewhere nearby.

12/13/12 5:00 PM

Have an electrician set up some 'backup' circuits for heat and fridge, and the bathroom circuit. You should consider a switched or relay system that will take out the meter pan and put in the gen etc.

12/13/12 5:19 PM

Just how much you need may depend on whether you need electric hot water, dryer, and some things like that, but my mom's house has about 6500 running watts, and without an electric water heater that keeps things pretty much transparent and even allows electric drying if it's planned for. I have a tractor generator with about 6000 watts continuous, and that's quite enough for my house as long as I turn off the electric water heater, and ration use of things like the electric oven. For lights, heat, TV and all that sort of thing, it's more than enough.

If you're looking to power only a part of the house, and don't need power for things like water heater and water pump, a smaller one will probably be enough. Some generator makers have checklists you can use to figure out how much you need.

My house has such a complicated and multi-breakered system (furnace, power vent chimney, water pump, subfeed breaker box in the kitchen, and so forth) that I cannot reasonably run it any way but by feeding the whole system. If your setup is a little less complicated, you can select a half dozen or so circuits, including refrigerator, important lights and the like, and economize on both the generator and the installation. You can buy a "downstream" transfer switch that powers only certain circuits, and that can be installed without interrupting the power to the whole house.

I've been shopping recently for a new generator, and from what I've seen so far, those running in the 6000-6500 watt running range are still pretty good bargains with little if any gas penalty over somewhat smaller ones. A size or two bigger gets much more expensive.

As it happens, there's been a shortage of generators since the last storm, and though there are plenty of 5000 watt ones showing up, larger ones, especially with electric start, have not yet reappeared. There's also a shortage of transfer switches, and the electrician I hired to make my system legal has had trouble getting one. Up until now I've been illegally backfeeding, but to do this safely requires with no exception ever that you disconnect the main breaker and double check everything, so for a system that might have to be operated by someone else, the risk is too great.

If I had piped in propane or natural gas, or used it for anything else, I'd certainly use that. A tank just for that is too expensive for the relative rarity of power failures here, but I'd spring for propane if I needed it for any other appliances anyway.