Wires are MELTING!!!!

We have 2010 Jayco 32BHDS Travel Trailer, bought it new from a dealer in the fall of 2009. No problems until last year. We returned to our campsite after a day at the local amusement park to find no power on our site. Our TT had tripped the breaker on the campground pedestal. We flipped the switch back on and it ran for about a minute before tripping again. It was late so we decided to just leave the electricity off and deal with it in the morning. Called a mobile tech out and he stated that it looked like a wire had come loose in travel in the main power supply and arched inside the metal junction box. He fixed up the wiring put on new wire nuts. We ran the electric water heater and A/C for about 6 hours and started to smell burning plastic. :E Turned off the water heater and a few minutes later the breaker tripped on the pedestal again and would not turn back on. Called the tech out again and he said the original issue caused a problem with the transducer in the A/C unit and it was pulling to much power. He replaced the A/C unit with a new one we purchased and picked up from CW, a put new wire nuts on AGAIN. All was well for the remainder of the trip, about 4 days. We used the TT for hunting season but did not use the A/C or Electric HW and of course had no issues.

Just used the TT for the first time this season over the weekend. Got to the CG and about 30 minutes after turning on the Electric water heater and A/C we smelled the burning plastic. :M Sure enough the twist nut was melting. Turned off both the water heater and A/C. Next day turned on just the fan and immediately smelled burning plastic. The wires were heating up using the microwave too. Urghhhh!! What is going on with the electrical system and why aren't we blowing a fuse or tripping breakers before the wires start melting and smoking?!?!?