30 amp to 50 amp adapter tripping breakers

Using a 30-to-50 amp adapter (or the reverse) and tripping breakers usually means your actual total load exceeds what the smaller service can provide — a 50 amp rig running on a stepped-down 30 amp connection has to manage load carefully (can't run two ACs and the water heater element simultaneously, for example). This isn't a faulty adapter issue most of the time, it's a load management issue. What are you running when it trips?