Large enough generator?
September 14th, 2011
Our power went out due to wind damage from hurricane Ike, in Pennsylvania. We have not had power for 4 days now, but luckily I was able to get a generator and have saved our fridge and freezer. My question is what can I power with this generator. It is a 5000 watt generator, and I was told that this should be able to power the whole house. Only thing is, I have a lot to run in my house. We have well water, heat with an electric heat pump, which has electric back up heat, and also an electric hot water heater. The well pump has a double pole 20 amp breaker, hot water double pole 30 amp breaker, heat pump double pole 25 amp, and furnace double pole 60 amp and double pole 30 amp. Will the 5000 watt generator be able to power any one of these at a given time? I know I am SOL for using them all at once, but switching between them would not be a big deal to me. Also, I know that I should not back feed into my house, and plan on getting a manual transfer switch to do the job. I just need to know if I need to get a bigger generator before I start looking at transfer switches. Thanks for the help.
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Posted in Wind Power Energy | 
Tags: amp breaker, electric heat, electric hot water heater, freezer, fridge, furnace, heat pump, hot water heater, hurricane, job, pennsylvania, sol, transfer switch, transfer switches, water heat, watt generator, well pump
It’s do-able, but not everything.
Your Heat and A.C. draw more than the generator puts out.
(Luckily it’s mild fall weather).
5000W. @ 240V. is about 21 A. – that’s your generator capacity.
You should be able to start & run your well pump with nothing else connected. If you’ve got a pressure tank, fill it, and switch off.
Now you’ve got drinking water
Your hot water heater probably has two elements.
Can you get at the controls and only run one?
It’ll take more time, but the tank will heat up eventually.
Between times run the fridges to save your food and you can have
some lights and small appliances.
You can back-feed, but if and only if
YOU ARE ABSOLUTELY POSITIVE THAT THE MAIN BREAKER
IS DISCONNECTED, (OFF), AT ANY TIME THE GENERATOR
IS CONNECTED.
A mistake here can kill somebody.
To run that whole set-up with electric heat, you’re going to
need a ‘genny` in the 25-30KVA range.
Congratulations on surviving the hurricane.
For starters, no, it’s not enough to run YOUR house. Who ever told you it was large enough probably doesn’t know what their talking about or didn’t know about the amount of amperage your house needs. An easy way to do it is run what you feel is necessary first. Your well pump, refrigerator, freezer, & lights are probably fine with 5000 watts. Usually generators have 240 volt capability with the right plug and cord, use that. Establish a safe way to connect 240 volts to feed your panel through your cord. I installed another cord end with a male dryer (30 amp) cord end on it. Then you can simply unplug both ends when power is restored. Turn your Main breaker off on your main service, to ensure not to back feed when the power is restored. Keep a good communication with neighbors and power company to find out when to shut your generator off. shut off generator and disconnect any cords and other wiring you have hooked up for your generator before you turn your main breaker back on. Remember to be very careful around your temporary wiring. These are the times when we usually need to do things that we wouldn’t normally do. Be safe & good luck.
Your best solution is to call a qualified professional electrician/ contractor to do the work. From what you mention, I guess you’ll need a 20KW to do the whole house.
Start by making a list and checking it twice for all of the required electrical appliances and the loads for each and the voltage.
Freezer 15 amps
Fridge 15 amps
TV/ VCR 15 amps
Water pump 9 amps (240)
Water heater 4500 watts
When you are done totaling them and make some decisions about what else you want you can then decide with the advice of the electrician just how big you need and what you want.
Use a microwave for cooking, not an electric range, gas is more reliable for heat and water tank than electric during a storm.
When you get the total, add 25% for sizing since the gensets are rated peak and should be run at 80% load. Hope this helps. A 20 kw unit gives the option of LPG or propane and many other items. During a power failure gasoline and diesel are both in short supply since the tanks are buried and the pumps do not work.
Here is a link that will help you figure out what size you need to run as many appliances as you care to.
http://www.homegeneratorsystems.com/buying_guide/se
I’d consider the generator to power all but the furnace, although not all at once. If you hope to include the furnace you’re looking at upwards of a 20kW generator.
During outages I power twelve circuits in my house with a 5500 watt generator. Oil fired furnace, fridge, freezer, well pump, and several other circuits connect to the transfer panel. There isn’t any power to spare, but I can’t justify the expense of upgrading for the few outages that happen.
I may have other items of assistance on my web page listed below.
yes, one at a time,
to power your whole house you will need at least a 10 Kilowatt to 15 K generator
i have a 6000 w gen and can run my freezer and fridge but that’s all
wont run the well pump. or hot water heater, or heat.
that’s why i have a wood stove ,for back up.
No it will not run all of that. You will have to choose which two to run at a time. I’m sure the freezer will stay cold for quite awhile while you use the well pump etc. etc. Just run the appliances as you need them,,,not overloading the generator.
Glad to know you are at least safe from the wind damage. We had a lot here in Indiana as well.
While the circuit breaker usually doesn’t represent the total amount of load, it is usually within 80% of the breakers capacity. I.E. an 20 amp breaker is allowed to carry 16 amps continuously.
The fastest way to get an estimate on wattage is to take the breaker rating and multiply it by the voltage. Your 2 pole breakers will be 220 – 240 volts so use the high number for safety.
20 amp breaker x.8 x 240 Volts = 3840 Watts.
This won’t be 100% accurate but it will give you at least an idea of what a certain item will pull.
I’m sorry to say this but who ever said you could run your whole house on 5000 Watts surely didn’t know what they were talking about.
Any other questions feel free to contact me from my website.
http://www.rickdoan.com