Generator to Furnace?


Old 01-31-11, 10:08 AM
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Generator to Furnace?

Preface - should have had a transfer panel installed before the epic freezing rain/ice/snow storm about to hit St. Louis.

Only planning this as a last ditch option if I'm stranded with wife and toddler and infant.

I am comfortable with electrical work, have done a lot around the house, but nonetheless an amateur. I am a mechanical engineer by training.

I have the typical metal switch box at my furnace, a multiphase Bryant gas powered, that takes 120V. I would disconnect the wires from the panel and switch off the furnace circuit at the panel. No backfeeding here. Then I would connect a tool replacement cord with male end to the furnace wires and plug it into a 12 gauge extension cord from the generator. The generator is 5000W and I have a ground wire to run from the frame to my existing rod in the ground.

Does anyone have any suggestions? Last time we had an ice storm, power was out for a week.

I really appreciate it.
Old 01-31-11, 10:41 AM
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Originally Posted by Squire View Post
I would disconnect the wires from the panel and switch off the furnace circuit at the panel.
You would only want to disconnect the hot and neutral wires from the panel. The ground should remain connected to both the house electrical system and the generator cord as that provides connection to earth ground. It would also be a really good idea to install a cord strain relief fitting in the furnace box to prevent the cord from pulling out of the furnace when you trip on it in the dark. In the box, connections should be made solidly with wirenuts.

While you're at Lowe's getting the appliance cord and strain relief fitting, check to see if they have any single circuit transfer switches in stock as this would really be the best way to provide emergency power to the furnace. The cost is something like $70 and it's no more difficult to wire up than a cord, so it's really not much more trouble to do it right.

Example: Reliance Controls TF151W Easy/Tran Single-Circuit 15 Amp Furnace Generator Transfer Switch For Up To 1875 Watt Generators: Patio, Lawn & Garden
Old 01-31-11, 06:29 PM
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Good luck, Squire. What area are you in? It has rained most of the day and the temperature is about 30 to 32 now, everything is glazed and slick. Sleet changing to eventual snow should be starting in the next 8 hours or so. I am hoping the media has this storm blown out of proportion, but we shall see. The prediction of massive power outages has most people kind of spooked.
Old 01-31-11, 06:55 PM
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Thanks for the warning, casual joe!

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