My son had this exact problem with a new trailer. When I measured the voltage at his pedestal, it was 105. In my experience anything below 110 is asking for trouble. He reset the breaker multiple times before giving up. Eventually we replaced the breaker to eliminate the possibility of it being weak. The last 5 trailers in our family have all used a tandem 30/20 amp Homeline breaker--I think that they are pretty common in 30 amp WFCO systems, and also pretty hard to find in home stores. I had to order one for my son, and now carry a spare for myself. I suggest buying the digital plug-in volt meter that camping stores commonly sell that will alarm on ground faults and frequency faults (and maybe low voltage although it has not happened to me). I also suggest getting the Camco 50 to 30 amp dog bone adapter. Very often the 50 amp outlets are in much better shape than the 30 amp ones, and that will eliminate voltage drop caused by a bad fixture.
