Not sure if this is the proper forum or not...... There seems to be so much conflicting information on how to make this work. From what I have read, many furnaces will not operate off of a generator. I have read the cause is anything from a bad ground to "dirty" power produced by the generator. Is there any rules of thumb as to how to buy/connect a generator to drive a typical natural gas furnace? The only real load would seem to be the blower and that would not seem to require a large/expensive generator. As a follow up question, a saw setup for wiring a furnace to run off a generator that seemed safe and inexpensive. There was a "pig tail" wired into the power supply of the furnace with a typical three prong male plug. Attached to the conduit was a three prong outlet coming from the breaker box. Under normal circumstances the plug is connected to the outlet. In an emergency, the furnace is connected to a properly sized extension out to the generator. Safe or not?