A question for the Electrically Inclined

TXplt · 04-30-2008, 10:22 PM

Almost feel embarassed, having been an engineer at one time. But I've though up a scheme which seems like it'd work great which means it's fraught with peril.

For a temporary connection of a fuel powered generator into the mains of a house (without installing alot of switchgear) is there any hazard in the following (assuming the generator is properly grounded, etc.):

The generator has a 240V standard 4-Prong 30A output and the dryer line in the house has a standard 4-Prong 240 30A plug. Both have circuit breakers at 30A and the ampacity of the lines for the dryer exceeds this (i.e. no overcurrent or overheating problem in the lines, and all the lines are protected by CB). Would there be any problem with turning off the main breaker (thus isolating the bus in the house from the outside electrical mains), Plugging the output of the generator into a 4-prong output plug and plugging this into the dryer outlet (assuming all the wires were correctly connected). The power would then be flowing in from the dryer connection to the mains of the house and could power them and an appropriate wattage/VA of household items ?

All house lines are equipped with GFI.

Blackrock · 04-30-2008, 10:48 PM

That is kind of a 'McGyver' fix but I have done similar thing and gotten by.

Mooseman684 · 04-30-2008, 10:53 PM

I don't see why that would not work. I would put a sign on the Mains to remind you to UNPLUG the Generator before energizing .
Also, I would not use a Large load on the system as the wires will only handle so much amperage running it "Backwards" so to speak...No Electic stoves, or heaters, or dryers...
Rich

TXplt · 04-30-2008, 10:57 PM

Thanks--it seemed to make sense. I was also worried about neutral return currents, but I'm thinking that the grounded generator (along with the house's grounded neutral) would have that covered.

Maybe I'll try "ops testing" it.

sell33 · 04-30-2008, 10:59 PM

All we do at my gf's house is turn off the main and hook the cord for the generator straight into on of the 240 breakers like the air or dryer then just can't use w/e appliance we hooked the generator into....

Muddog · 04-30-2008, 11:27 PM

Pull your meter and leave it by the meter can. If you leave your back porch light on so your linemen can find your service thats on the ground is pretty helpful too

04-30-2008, 10:22 PM	#1
TXplt Lost in the Ozone Again Join Date: Jan 2008 Location: Fort Worth, TX Posts: 2,824 Images: 4 Blog Entries: 2	A question for the Electrically Inclined Almost feel embarassed, having been an engineer at one time. But I've though up a scheme which seems like it'd work great which means it's fraught with peril. For a temporary connection of a fuel powered generator into the mains of a house (without installing alot of switchgear) is there any hazard in the following (assuming the generator is properly grounded, etc.): The generator has a 240V standard 4-Prong 30A output and the dryer line in the house has a standard 4-Prong 240 30A plug. Both have circuit breakers at 30A and the ampacity of the lines for the dryer exceeds this (i.e. no overcurrent or overheating problem in the lines, and all the lines are protected by CB). Would there be any problem with turning off the main breaker (thus isolating the bus in the house from the outside electrical mains), Plugging the output of the generator into a 4-prong output plug and plugging this into the dryer outlet (assuming all the wires were correctly connected). The power would then be flowing in from the dryer connection to the mains of the house and could power them and an appropriate wattage/VA of household items ? All house lines are equipped with GFI. __________________ Old fighter pilots never die.....They just wind up in Texas

04-30-2008, 10:48 PM	#2
Blackrock Senior Member Join Date: Mar 2008 Location: SE Arizona's Gila Valley Posts: 261	That is kind of a 'McGyver' fix but I have done similar thing and gotten by. __________________ "I only use my gun whenever kindness fails" Forbidden fruits create many jams

04-30-2008, 10:53 PM	#3
Mooseman684 Super Moderator Join Date: Dec 2005 Location: Alaska Wilderness Posts: 9,668 Images: 2	I don't see why that would not work. I would put a sign on the Mains to remind you to UNPLUG the Generator before energizing . Also, I would not use a Large load on the system as the wires will only handle so much amperage running it "Backwards" so to speak...No Electic stoves, or heaters, or dryers... Rich __________________ You know you might be facing your doom,when all you get is a click when you're expecting a BOOM!

04-30-2008, 10:57 PM	#4
TXplt Lost in the Ozone Again Join Date: Jan 2008 Location: Fort Worth, TX Posts: 2,824 Images: 4 Blog Entries: 2	Thanks--it seemed to make sense. I was also worried about neutral return currents, but I'm thinking that the grounded generator (along with the house's grounded neutral) would have that covered. Maybe I'll try "ops testing" it. __________________ Old fighter pilots never die.....They just wind up in Texas

04-30-2008, 10:59 PM	#5
sell33 Senior Member Join Date: Feb 2008 Location: Ohio Posts: 1,194	All we do at my gf's house is turn off the main and hook the cord for the generator straight into on of the 240 breakers like the air or dryer then just can't use w/e appliance we hooked the generator into....

04-30-2008, 11:27 PM	#6
Muddog Senior Member Join Date: Sep 2007 Location: Northeast Kansas Posts: 127	Pull your meter and leave it by the meter can. If you leave your back porch light on so your linemen can find your service thats on the ground is pretty helpful too