Power source breaker tripping

[Belti Guy]

Hello All, I'm stumped. From January 2019 to March 2019 we camped in Louisiana, Mississippi, Texas, Oklohoma and then back to Wisconsin, with no problems! Our trailer (2007 3000 RK) is now parked at home and has been plugged in to a shop outlet since we got home in mid March. Had no problems until about two days ago. Now when ever I try to plug in the camper, the breaker blows within about 30 seconds. The camper is plugged into a 120 v 20 amp outlet in the shop with a 10 gauge extension cord which is on a reel with a on/off switch. From there I hook the rv power cord with a 15 to 30 to 50 amp adapters. Trouble shooting - first just plugged in the extension cord to see if it had a short. It worked fine. Then I unplugged the rv power cord from the camper and hooked up the power cord to the extension cord. No blown breakers! I then turned the main breakers off in the Monty and reconnected the power cord to the rv and the breaker blows almost immediately. I checked the water heater and the electric switch is off. It has just been parked this whole time on a gravel pad with mowed grass all around. Logic would imply that the problem is in the rv plugin or the wiring between the plugin and the breaker box, but I'm not sure what to do next! I'm relatively decent mechanically, but electrically my knowledge is pretty basic. Any ideas or suggestions? Thanks in advance. Doug

Moved to "Montana Problems" forum. Sorry