We Wrote The Book on Grounding and Earthing

Toll Free: 888.367.0888

Ask The Experts Blog

I am trying to run a propane furnace with a 3000 watt generator during a power outage. The furnace is run on a 15 amp circuit. I know that this size generator will run the furnace. More often that not a fault code is tripped in the furnace that says reverse polarity. The generator will run lights and refrigerator OK. Does the generator need to be grounded?

Hi Joanie,

Please be advised that you need to contact a Certified Electrician ASAP!

Thank you for your question regarding your generator and furnace, it is our pleasure to help.

Yes, your generator must be grounded; it is required under the National Electrical Code (NEC) even for temporary setups.

It sounds like your system has a number of fairly serious problems.  We recommend that you contact a certified electrician right away.  The reverse polarity issue sounds like you are running a single-phase 120-volt setup.  If that is true, a 15-amp breaker is only rated for 1,800-watts.  If you are running a single phase 220-volt system, you should not be getting a polarity warning, unless something is very wrong with the neutral connection.  In either case, you have a problem.  There are also some special disconnects that are required when you operate a generator, so that you don’t send electrical energy back-up and into the power grid, where it could electrocute line workers trying to repair the electrical grid in your community.  You also of course, must ground that generator for your own personal safety.

Please contact a certified electrician as soon as possible, you could have a serious life-threatening situation.

Best regards,

The Engineering Team at E&S Grounding Solutions


Photo credit:  http://www.flickr.com/photos/gavinmusic/2961453920/sizes/l/in/photostream/

Leave a Reply