How do I figure out the watts I need for a home electrical generator?

You need to decide what appliances you want on backup power. Things like a well pump, furnace, fridge, and freezer will likely come first. After that consider lights, cooking appliances, television, and so on. The required generator capacity will depend on how much load you expect it to power.

I power my house with a 7kW generator that connects via a 12 circuit transfer panel. It has all the necessities plus several comfort items. I can watch satellite TV and surf the net while others nearby don't have water to flush a toilet.

Read through my generator page for other information. An email link is included at the bottom.

http://members.rennlist.org/warren/generator.html

How do I figure out the watts I need for a home electrical generator?

For one; in your and most people’s case this will be an Emergency Generator and not a generator to go off line and use 24x7x365 so figure out what you need to run in the event of an emergency. In the winter heating would be your #1 priority, water if you have a water well with electric pump, refrigerator and lighting, you get the idea and not all of these will be running at the same time but most will. Now to your question, Volts X Amps will give you Watts so look at the items you’ll need ( not want ) need for a power outage of generally a few day’s or a couple of weeks depending on the history of the outages in your area. So 120 volts X the Amps rated on the individual items, 220 Volts on those items. This will be your get by watt rating add at least 1000 watts to your answer, this should get you going as to how big of an emergency generator you’ll need. Next check the service rating of the generator i.e. continuous run or occasional use. The difference between a good generator and a cheap one is only a few hundred dollars purchase a good one don’t go cheap here. Fuel tank size, get one with a large tank refilling can be a pain in the butt. You can also purchase a miniature gas pump looks like the real thing only miniature 20 gallons or so, this will really help in refueling. Ventilation! Do Not run the generator in your garage or any attached contained area CO is deadly and many people die every season from it. Connecting your items this is what I do, I trip all the breakers ( OFF ) you don’t want to back feed your generated electricity down the power line to harm the electrician trying to restore your power. I made an extension cord with a male plug in on both ends, and then I mapped out what electric devices are on a run of sockets i.e. one or two rooms will be wired together. I plug one male end into my generator and the other male end into a wall socket i.e. one that runs the refrigerator for sure and from that run of sockets you can run lights and other devices so you won’t need a bunch of electric cords running all over the house. Make up another cord just for your heating so two cords maybe all you’ll need to get you by?

Next, purchase an analog Volt meter that plugs into one of the 110 V sockets of your generator ( Radio Shack ) then plug it into your generator, start your generator let it stabilize then connect an electrical device and run it. Look at the volt meter and you can adjust the governor of the generator until it reads between 100 Volts and 140 Volts this is the loaded output of the generator. If the generator is running to fast the voltage output will be too high, if it’s running to slow the voltage will be to low either one will damage you appliances. Purchase gasoline that doesn’t contain any alcohol, alcohol is a killer for small engines; it will deteriorate the rubber seat of the carburetor. When you stow the generator away for the season treat the fuel with fuel stabilizer ( Sta-bile ) is one such treatment. Run the generator a few hours every month or so to keep the fuel system from gumming up. Enough said this subject can go on much longer it’s not plug & play it’s prepare and run.

I have a 5.0 KW 240 volt Single phase generator running on natural gas...It generally runs about $3.00 per 18 hr day to operate....In the winter.

It would not carry Elect heat.... Elect water heater....and Elect stove and Elect dryer at the same time

So I switched all three to nat. gas..

I am an electrician and sort of do it myself...I Have no idea what it cost other than the cost of the new appliances. There is little maintenance on the Gen/Engine . Change oil ETC. once a year.. only runs about 3 months a year...Just be sure the Gen. Has solid state controls

But I suspect it was worth it. No problems in several years

You will need to read a learn a lot I'm sorry to tell you because the range of options is very large. So are the range of costs. It depends what you want to do and how.

You can get a fairly standard generator for not too much if you are willing to run around with extension cords and run one or two items at a time plus maybe a light or two.

Plus you need a physical disconnect of the appliances you want to run from the power system. That is the law. Unplugging them and plugging them in to extension cords does that. That is what I do. Although we rarely have long power outages. But we had one a few years ago.

For instance on my boiler (gas but has a pump), rather than have the power wired directly to the boiler the power is terminated as an outlet. Then from where the power was wired I put a heavy cord and plug. Normally it is just plugged in the outlet. Then when the power is out I can unplug the boiler and plug it in to the extension cord from the generator. That is both legal and safe.

Once the house is warm I can then unplug it and alternate between items like the freezer or refrigerator. And those I only need to run a few hours a day. You just can't run too much at one time. A freezer will hold temps for day easily. And also, for instance, you can run both the freezer and refrigerator at the same time BUT you can't start them at the same time. They might draw only 150 watts running but for a second or two it takes like 1,500 watts to start them.

Or you could have an automatic system installed that power up a number of items in the house wired off the main panel with a generator switching box and spend $10k-$15k (estimate depends on size) for it.

My simplest suggestion is to get a used 3.5k to 4k generator and to do the extension cord thing. You would only need to make the furnace modification as I described, if it is gas. That way you would learn what you need or need to do. Can you get to the plug for the refrigerator for instance?

If you have a heat pump or electric heat, forget it. You need to find a different method of heat. Those would take a monster 220v generator. But you could run a small propane fueled wall furnace or circulate air with fans from a gas fireplace or wood stove.

But you have told us too little about what you have or want to run to advise you much. Every home and the need is a little different.

I read where GE recently has a new system for home generators. They install controllers on all the items you want to power in order to make sure they don't all start or are all powered on at the same time. But it must have a computer control board as well so it likely not cheap but it allows for a smaller generator for the whole home.

Without that, even with installing a generator panel off the main power box people still have to manually turn different items on and off so as not to run them all at the same time.

Good Luck.

7 Kw Generator

ZRX1200 is physically powerful. AC contraptions will start up up with a surge around 11-12k watts and settle to a run of around 6-7k watts. so which you go with for a minimum of a 10k generator in case you go with for to run your AC. you will desire to have the surge over the 12k mark yet maximum 10k turbines would have a surge of 15k

Unfortunately, there is no simple answer to that question because of the variables involved: City water or are you using electricity to pump water? Electric heat or gas? Hot water gas or electric? On and on.

Your best bet will be to look at your electric bill and see what your usage is per month. Personally, I would look for the month that has the highest usage and build my generator-buying plans around that. Our electric company out here (OR) gives you the last twelve month history in dollars and their website breaks it down by usage per month. I imagine most companies do the same.

You failed to give enough info for us to give you an answer. If you have electric heat only, then forget it unless you want to invest several thousand dollars for a genset large enough to provide electric heat (at least 20KW). Otherwise a 6 or 7 KW genset would provide the basics.

here's a guide..

http://www.generators.smps.us/sizing.html