What size generator?

[gsb]

The house I bought has an extra electical panel wired for a generator. Runs the furnace, refrig, some lights and some outlets. It has a long thick cord with a plug on the end with 3 large prongs, similar to an r.v.. There is a breaker in the box labeled utilities which I assume you shut off when using the generator and flip on the breaker labeled "generator supply 60 amp". Can anyone tell me what size generator will work with this? Also can I wire in some deep cycle batteries into this? Any help would be great.

[kawalekm]

Hi GSB

Two numbers to look at. Add up all the loads you can expect to ever have on at one time, then double that number to take into account the "starting loads" for each appliance. Lets say your frig uses 400 watts, the furnace uses 1500 watts, the microwave uses 800 watts, and the television uses 300. Add that up and you get about 3000 watts, continuous. Double that number and you get 6000 watts, so a 6kw generator would fulfill your needs.

Since your breaker is rated at 60 amps you should not try to draw more than about 7.2kw through it. Realisticly, I would sugggest that a generator between 5 and 7.5kw would provide the best service.

You could to the same thing with batteries and an inverter. The deep-cell batteries can be charged from regular grid current when the power is on normally. With a power failure, the inverter would feed power through the same plug the generator would be plugged into. Again, the inverter and batteries need to be sized the same way the generator is.

Before actually trying to hook anything up, I would pay an electrician to take a look at it to guarantee that it is wired correctly. The danger is that if the house is not properly disconnected from the grid during a power outage, your generator could be sending current down the grid to an unsuspecting lineman trying to restore power. Lineman have been killed while working on a supposedly cold circuit that was getting power from a remote generator.
Michael

[gsb]

Kawalekm, thanks for the info. I notice I forgot to mention there is a metal toggle? that prevents both breakers being on at the same time. I would have to turn off the utility breaker before I could turn on the generator breaker. thanks again, gsb.