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Portable generator electrical connections questions

Posted by jbaugh (My Page) on
Wed, Aug 11, 10 at 9:58

I have a 4600 Watt portable generator in a shed just outside of my garage for use for emergency power generation.

I'm concerned about how the electrician has configured the connection with the house circuit. He installed a double throw safety switch about 25 ft away on an interior garage wall. A heavy gage cord with a 3 prong male end dangles from the switch box for connection to the power cord connected to the generator. When generated power is needed, a power cord is plugged into the 3 prong 125V outlet on the generator with the other end connected to the cord from the safety switch. I have run this configuration several times for testing and during brief power outages. It seems to work as long as the power draw from my house is kept relatively low ( two refrigerator/freezer combos, 8 or 10 75 watt light bulbs, computer, clocks and other low wattage items). Occasionally the generator seems to falter a bit and I notice the lights dim briefly.

Is this the optimal way to transfer power from the generator to my house circuit? I notice there is a circular 3 prong locking outlet on my generator. This is labeled as a "120 V 30 A Twist-Lock" which "powers 120 Volt AC, 60 Hz, single phase loads requiring up to 2300 Watts of power." The standard 3-prong outlet is labeled "to operate 120 Volt AC, single phase, 60 Hz loads requiring up to 20 A or 2300 Watts of power."

All this suggests to me that I can only supply up to 2300 Watts of power from my generator to my house through one of these connections and I am not getting the full potential 4600 Watts. Is my assumption correct? Is there a way to remedy this so that all 4600 Watts of my generator are available?
Thanks.
John


Follow-Up Postings:

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RE: Portable generator electrical connections questions

ISTM that you would only get the full 4600W if you had a (balanced) 230 Volt hook-up (2300 Watts on each hot leg).
Is there a 230v receptacle on the generator panel?
I would think you should have a 4-pronged (locking) plug connecting the generator 230v output to the transfer switch, which would then selectively power only your essential circuits, limiting the probable load to about 75% of the generator rating.


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RE: Portable generator electrical connections questions

This setup sounds like you're just feeding the generator into the main panel and there is no transfer switch and separate box allowing your generator to power selective outlets. Not any different from a former neighbour of mine who just plugs his generator into a garage outlet and is convinced it's fine, though the lights are all dim and he's backfeeding the incoming power lines. Perfect for electrocuting linesmen and damaging your appliances. Was the install done by a licenced electrician? Depending on your jurisdiction, you may be able to get a free inspection from your local power supplier.


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