Friday, March 12, 2010
Posted by RV Doctor
I have a Generac gasoline generator in my motorhome. I started it up and it was running fine for about five minutes. Then it stopped putting out any electricity, but the engine is running fine. The 20-amp circuit breaker on the unit had tripped. I reset it and still no output. I have checked both circuit breakers with an ohm meter and I show resistance in the closed position and none in the open position. I checked all the breakers in the coach and they seem fine. Could the problem be further down the line? What is a "J-Box?” Any idea what else I should check? Karle, (Littleton, NC)
Karle, if you are sure the circuit breakers are okay, then there might be something more serious to contend with internal to the generator. First, with the generator running, check for AC voltage at the input to the circuit breakers. This will rule out the breakers and anything downstream. If there is no voltage or lower than normal voltage going into the circuit breakers, then the problem is likely a bad voltage regulator, rotor, or stator on the generator itself. All of these components are very expensive and difficult to replace and they mandate you take the coach to a qualified Generac dealer or service center for repair.
Also check the voltage at the output of the circuit breaker. If there is voltage at the input to the breaker but not the output, then the breaker is faulty, even though it passed your continuity test. It may break down under current flow and/or higher temperatures. The J-box you referred to is the junction box. It is located fairly close the generator and is the transition connection between the flexible cable coming out of the generator and the conduit going into the coach. If AC voltage is present at the output of the breakers the next place to check is inside the junction box. Remove the cover and inspect and probe the wiring. If there is power there then the problem is further downstream of that. You did not mention whether you have to manually plug your shore power cable into a generator receptacle or whether you have an automatic transfer switch. If you have a transfer switch, that is likely to be the problem if the rest of the areas check out as good.