Emergency generator and panel feeding.


Old 02-26-11, 10:44 AM
Thread Starter
Join Date: Oct 2000
Location: NE Conus
Posts: 498
Emergency generator and panel feeding.

I would really appreciate some input here. I recently bought a new B&S model 30471 8000 watt 30 amp emergency gen, which has a bonded ground. I would like to be able to connect this to my main house supply in case of power outages. I plan on using a outdoor plug connection but am in a quandry as to the main panel.
Is it better to use a 10 circuit transfer switch or a 200 amp (my house service rating) panel? Both of these items would include meters to monitor, and balance, usage.
The main things the gen would be supplying are boiler, refridges, some lights to be determined. I am presently leaning towards a switch but open to suggestions. Any ideas, or opinions, both pro and con gladly entertained?
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Old 02-26-11, 12:20 PM
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Join Date: Apr 2008
Location: Oklahoma
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you will need a transfer switch and you will only be able to run just a very small amount of things with that small of a generator, you must make sure that the transfer switch removes your house from the incoming power supply so as to not back feed into the commercial system or it will be deadly for line repair crews. 8000 watt is pretty small for home use in emergencys.

Murphy was an optimist.
Old 02-26-11, 12:37 PM
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
In my house I would consider an 8,000 watt generator supreme overkill. I could run everything but my kitchen range with that large a gennie.

Unless you are on a private well for your domestic water or have a sewer lift pump or something with a septic tank for sewage I think there is little need for a full panel transfer between utility and generator. You also have to consider how often and how long are the utility outages. Some places need to consider air conditioning during power outages and if you do (or have the aforementioned pumps) then you will need a larger gennie. On the other hand if you have a gas-fired furnace (or boiler) and a gas (or oil) fired domestic water heater then all you really need is to be able to run the furnace/boiler (and circulation pump), refrigerator, freezer (not necessarily at the same time) a microwave oven and/or toaster oven along with the television/DVD and a few lights.

I can run my furnace, refrigerator, TV/DVD or computer and enough lighting to get by with a 2800 watt 120 volt gennie. In my particular case it was easier to recircuit these loads to a separate sub-panel and feed the sub from the main or generator via a transfer switch. Transfer panel would have worked just as well but in my case it would have been more expensive.
Old 02-26-11, 01:07 PM
Thread Starter
Join Date: Oct 2000
Location: NE Conus
Posts: 498

Thanks for the comeback. I realize that the panel would have to be isolated from the main line so as to avoid feedback.
As to the size this is 8000 with a surge to 10500. I computed it before I bought to our power use and it met our needs with the required buffer allowance. We do not have any heavy draw items (ie; C.A.C., pumps (except sump)) and will be for powerouts and maybe some renovation work.
I think that I will go with the switch and get the 10 circuit one so that the boiler/fridges/lights will be on their own seperate circuits. Now to prioritize which ones I need beside the essentials.

Furp; Our outages sometimes go from one day up till the last one that had some of our neighbors w/o power for two weeks! We were lucky as we dealt with a friendly lineman and we were able to point out to him the pole that had the fusible link that had blown and that was two days. What you are supplying is basicly what I would be doing.
Old 02-26-11, 02:12 PM
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Join Date: Apr 2003
Location: USA
Posts: 926
I have a 3500 watt generator that is overkill at my house during a power failure, but then again I suppose it depends on what one would consider an essential load that needs to be powered during a power failure. A few lights, the boiler, a microwave, the fridge, and maybe the TV do it for me.
Old 03-02-11, 06:55 AM
Join Date: Mar 2010
Location: USA
Posts: 2,854
The worst stumbling block for a small generator is the startup current draw of a refrigerator or a furnace or a pump.

For most home installations a generator must have neutral and frame (ground) unbonded. But if the actual connection between the house and the generator includes a cord with a plug, then there are ways around it if it is not easy to so unbond the generator.

When a generator is connected to a subpanel and the transfer switch in between does not have neutral and ground bonded when in the "gen" position then the generator itself should have neutral and ground bonded.

Never connect a generator to a regular (female) receptacle using a cord with plugs on both ends. Never actually construct such a cord.

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