Here's how it works on the 430
The other post regarding the P42 was correct in that it also applies to the 430. The large round Guest switch on the right as you face the panel is just for inverter draw. It does, I think, have one other fundtion, in that if it is set to both, even when the inverter is not being used, both batteries are linked together in parallel into one house bank, so if you want to operate each as a seperate bank, you must not use the "both" position on this switch. But the toggle switches in the middle of the panel supply 12 volts to the main circuit bus, either to the A or B breakers (only one can be selected at a time). For the life of me, I have no idea why there is an A and B selection here... it seems to make no sense, but that's what there is.Another interesting thing about the wiring that I discovered last summer is that you can start the boat with no starting battery installed! If you doubt this, just try it. I removed mime to use with my camper on a camping trip last summer, while the generator n the boat was being serviced. When I got back they said it ran just fine, and I was astonished, as I didn't think it could be started. They said it cranked up just fine! So I checked, and sure enough you can start the genset or the engine from the house batteries. something about drqwing voltage across the battery isolator. If anyone understands this better than I, I'd appreciate an explaination.George KornreichS/V Fiddler