Tripping Elect Box at Park - not at home

[momthebaum]

We have a flagstaff super light. Last year we arrived at a campsight, hooked up and blew the circuit breaker -- 30 amp. Park ranger came out, replaced their fuse, no luck. So on the way home we stopped at an RV sales/repair, they found nothing wrong with our RV. Second time was last fall at another park, the Park Ranger came out and replaced the panel - all worked great. Then we just went to a third separate park, plugged in and the breaker popped at the parks electrical box every time. Checked all our fuses, checked our power cord - no problems there. This time it was a city park - they sent their electrician who replaced everything in their box - yet it still happened and we spent the weekend running off gas and batteries. We got home, plugged her in, and no problems at all - everything works again. It has a brand new inverter (or is it converter? - hubby knows) and that is our second one in 5 years. We travel to parks probably every weekend of the summer - so the problem seems to be hit or miss. Any ideas? The parks say its our rig, the repair guys say it's the parks electrical boxes. We are stymied.