I am having my new house in Florida set up so that I can plug a generator directly to the system without having to use extension cords. Current receptacle setup is 30 AMP. As such what watt generator might I need to power everything (fans, frig etc.) except central AC? My original plan was to use a 9500/12000 generator. However, from what I read to benefit from that size I would need a 50 AMP setup which might be overkill vs. a 7500/9000 smaller unit running at 30 AMP max. I am no expert, opinions welcome! Obviously the smaller 7500 unit is a few hundred bucks less than the 9500. I am looking at such brands as Generac and Westinghouse which is loaded with options but doesn't have the same service network from what I see.
30A is plenty for everything except the 220V stuff. I have a 15000 going through a 60A breaker and 6 wire into my panel. Runs on Gas or propane
I'm not an electrician but I've learned a lot about electricity after debugging my daughter's bad meter base issue. I run my 3550W/4550W unit off of extension cords so I'm also interested to see what is recommended. I do know that if you want something like that you will be required to install an interlock that blocks your generator from energizing the outgoing power lines to protect linemen that might be working on those power lines. Some people have cheaped out. They thrown the main breaker and plug the generator in with a double pronged cord that is then connected to plug in the system and the breakers they want to power flipped on. This can end badly and I would not suggest anything so reckless. A question for you. Since you are running one 30AMP is it a 120V unit and are you going to only energize half your breaker box? The breaker box generally has two legs of 120V and combined they make 240V for AC, stoves and driers. To do it properly, you would want a slab-mounted unit with sufficient capacity to carry whatever you need during a sustained outage. Dual fuel units are nice in giving you options to stay powered.
Your power company can provide a special meter that has a receptacle to plug the generator into. They also make breakers to plug into your breaker box to back feed a generator. During hurricane Irma I ran my entire house with an 8KW Miller Bobcat including the A/C (I back fed it through the A/C compressor breaker) , I had to turn the water heaters off to run the A/C and vice/versa. I also have a 2.3 KW Coleman generator that runs my frig, TV and lights and is only half loaded. If I were going to buy a new generator today it would be a 10 KW.
Briz, 15KW will run everything in a house no problem, A/C, water heater, frig, everything and run you neighbors frig to boot.
You are so right! If your generator is running the main must be manually turned off . The best set-up is the use the power company provided connection that takes care of that. Of course, if you didn't turn the main breaker off you would know it right away because you would be powering the entire neighborhood and the breaker on the generator would trip immediately.
Ive done a test run with shutting the garage / shop sub completely off. There is 2 A/C in the main house and one in the shop. I'd only run one at a time. Its a portable unit that I mounted in a small enclosed with a cooling fan drawing fresh air over it.
I just installed one of these boxes to connect my generator. Had to select the important circuits, gas furnace, refridg, basement lights (computer modem), main floor lights and 2nd floor lights. The plug for the generator is outside. Have not had to use it yet but its there instead of running extension cords. Reliance 31406CRK $299.99 Manual Transfer Switch, 60A, 125/250V | Zoro.com I always have a full tank of gas in the Buick and 20 gallons in the boat to syphon if fuel is unavailable for some reason, like for 3 days after we got 6 ft of snow in 24 hours.
Planning on getting a 16KW backup gen this spring. Looks like it's going to run about 9K. Ouch! more than I was expecting. KID
To keep it simple I have a 7.5 KW generator with electric start. I shut off my main breaker, turn on the 30 amp breaker for the generator and it will run the entire house except the a/c compressor and other 220 volt circuits. And, if I turn off most all the 120 volt stuff (except the fridge), I can even run the 220 dryer or my well pump. When the well pump builds the pressure back up, I turn its breaker off and all the 120 breakers back on. Worked fine during hurricane Irma for over a week.
I used to backfeed 220 from my 9000 portable. Setting it up was a pain for my wife when I wasn't there, as well as having to refill it on long outages. Bit the bullet and had a 20k propane unit installed. Everything is automatic now. Power goes off, generator comes on, then when power comes on, generator goes off. You barely notice when it switches.
Same thing we do here with a 7.5 KW generator. The generator uses a long cord to plug into a 220 welder outlet in the garage, and sits outside in the driveway. This back-feeds the panel. We have certain breakers marked to be on in the main panel when this happens. So, the main is switched off and only those circuits deemed necessary are left on. That way the generator is not overloaded and there is no risk to line workers. This usually happens once or twice a year here in the winter related to ice. There is power to the well pump, furnace and circulators, refrigerator, stove, car charger, computer, a few outlets (coffee maker!) and the lighting for a few rooms. It is not automatic, but the drill is complete in a matter of minutes here and civilized life can go on one 220 appliance at a time. Cheryl
I would go with the bigger one. 10k will keep you comfy. Anything less and you may regret it later on. FWIW, diesel is the best bet. Fuel wont go sour, they use significantly less than a gas job. Propane ones are nice but burn through fuel. An extended outage will have you chasing all over for gas and propane. I run a 12k diesel, and even at 75% load, it burns about 1/2 gallon per hour. I can run everything with it, well pump, electric dryer, a/c units, fridge, freezer etc without having to worry about overloading it. Plus, the diesels are MUCH quieter. My old 10k generac gas job with a 2 cyl robin engine could wake the dead.I called it the howler.
Mine has lockout bracket such that in order to turn on the dedicated breaker to feed the panel from the generator, the main has to be shut off. It's a very simple sol'n to avoid backfeeding the grid. I can post a pic if anyone wants to see (I would now but the cover is off the panel).
It's pretty simple (I think - I'm not an electrician so feel free to correct me here) - The wire size going from the main panel to the generator receptacle is going to dictate the max. amperage. Of course that's assuming the receptacle & breaker were properly sized for that wire but if the wire is oversized (unlikely - $), the ends are easy to change so you're @ 30A max. A simple calculation (ohm's law) will tell you how many watts you can draw and hence what the max size generator you need. You could run a bigger generator but you run the risk of overheating the wire if the circuits on the main panel draw too much. The only variables are knowing how many watts ea. circuit you want to run will draw & if you're running any 240V circuits off the generator and deciding how to proportion that into the mix as they'll draw ½ the amperage of the 120V circuits.
I learned the hard way (Mt. Pinatubo eruption in the Philippines) how valuable a generator is during an emergency. So when I bought my home I paid an electrician to come in and install a 50 amp plugin system (separate breaker box containing the "have to have" items in the house and a cutoff switch to stop back feed into the power grid) for my 12,000 generator - bought one that uses both petroleum fuel and propane. I keep a 35 pd bottle of propane with the generator as propane lasts longer than petroleum. A very worthy insurance plan...
