Re: 3700 SY -- 120V Electrical system
I'm on the east coast, on the Chesapeake Bay. The dealer is in the Baltimore area, and his service dept. is totally incompetent. So I started corresponding with Dave Crosby, who is the National Service Manager in Seattle for Maxum/Meridian/U.S. Marine, so I'm not sure if there is anybody much higher who might provide better service. Crosby stated that the main reason they put all those big loads on Line 1 -- two A/C's, water heater, and Microwave -- is mainly because many marinas in the country have only one 30-Amp receptacle per slip, and the owner uses a splitter to get power to both Lines. Not a 50-Amp splitter like you mention, but a 30-Amp to two 30-Amp splitter.
Regarding the parallel switch -- mine is located directly under the "Ship's Power" switch for Line 2, so it can't be turned on unless the Shore Power switch on that side is OFF, and the interlock slide is raised. Only then can I turn the Ship's Power switch ON. But the indicator light for the parallel switch is always lit, whether the parallel switch is in the ON or OFF position, which seems to indicate that the parallel function is always energized. But apparently not, because I was always plugged into two separate 30-Amp receptacles when using Shore Power, and it overloaded and burned Line 1 only -- that indicates that the lines were not in fact paralleled. Regardless, it's a very unsafe situation -- I'm very lucky my boat did not catch fire.