All, I picked up a 1993 380 Tournament with 6-71 Detroit. two weeks ago and we have been fighting/figuring out electrical things. I am trying to figure out the House power supply. On the electrical panel, it seems that both feeds are from the same battery (via voltmeter). I have traced out both supply lines. From the battery 1&2, These leads go to the disconnect switch. The disconnect SW. feeds the emergency solenoid. Also feeds this black box with a push-button breaker(not a clue what this does). From there it looks to go to the electrical panel. Also, this box feeds the bilge pumps. There is a glass type fuse holder on the top of this box. And there is an 18 gauge wire with a fuse holder coming out the bottom. Each battery has its own black box. It almost seems to auto-switch when I disconnected the battery lead. The house power comes from cranking batteries.