Troubleshooting Call

[MAC702]

That was already tested by customer and retested my me. This genny ran other household appliances, like a subzero refrigerator and others equipment.

That doesn't mean its tolerances haven't fallen into nuisance tripping. It's an easy and cheap job and many times solves the unknown problem. It's not something you can really test for.

Indeed, you did test it. With a furnace that works elsewhere, but not on this receptacle. It failed that test.

 

[kwired]

That was already tested by customer and retested my me. This genny ran other household appliances, like a subzero refrigerator and others equipment.

Was you running other appliances at same time as the furnace? And if so all through same GFCI?

That can make a difference, even if running all same appliances through a house GFCI it could possibly still trip the house GFCI. But under ordinary conditions you don't have all those running through the one GFCI. Leakage current of any individual appliance may be fine for the GFCi, but put all them together on one line and it adds up to enough to be over the 4-6 mA threshold. Not saying this is what you have going on but something to consider.

 

[Michael15956]

Was you running other appliances at same time as the furnace?

No, furnace tested alone, tripped genny gfci.
Reset genny gfci, tested refrigerator alone, ran fine
Same for other equipment, genny gfci did not trip

Again, removed internal ground from frame of furnace, plug the furnace into extension cord that was connected to the same genny gfci receptacle, furnace ran fine. Thought I had a neutral to ground fault at the point, until this furnace was plugged into a house gfci, with the internal ground reconnect and it held fine.

 

[Wire-Smith]

to check if double bond is your problem you could temporarily lift generator egc to all premises ground connection and then check continuity from premises ground to generator neutral with furnace plugged in. ryobi sounds like an economy grade square wave generator, the honda that was suggested earlier would cure that if that's what the issue is.