1. NOTHING wrong with starting the chassis engine when plugged into shore power.
2. Staring the Genset when plugged into shore power IS a NO NO. The reason being--- Ideally, you NEVER want a load when activating the 120 transfer box relay's. Odds are, IF you start the Genset when plugged in, you will have a good amount of load (AC units and such) already running. When the Transfer relay's open and then close to Genset power, THAT load spike affects the points in the relay's and will degrade them over time. Will cause them to arc and burn slightly. Over time this adds up until they do not make a good contac and fail. Some RV'ers will turn the 50 amp gang breakers OFF at the RV breaker panel, before connecting Shore Power or activating the Genset. Then once the Shore or Genset has transferred, they turn the breakers back ON. Doug
