Hi folks, just getting used to me new to me B331. One red is for house, the other marked starting.......what is the "Negative Common" black switch for?
If your vessel is wired like many Bene's you don't likely have "HOUSE" and "START" you simply have two battery banks that are
in parallel when both switches are set to ON. Leave both switches set to ON, and discharge too far, and you're dead in the water. I have a number of Bene & Jenneau customers who've learned this the hard way..
Unfortunately many, but not all Beneteau's, have a bussed switch system where by HOUSE and START switches are permanently bussed together on the load side of the switches. Any time both red switches are turned ON both battery banks are
in parallel. Many owners are unaware of this wiring scenario and incorrectly assume they have "isolated" HOUSE & START banks.. If your boat has this wiring it is best to correct this issue.
Below is what this wiring looks like. The issues are listed on the drawing, if your boat has this wiring scenario. Link to full size image if needed:
http://www.pbase.com/mainecruising/i...1/original.jpg
The diagram below (drawn for a customer) corrects for the Beneteau bussed switch system and adds alternator to house bank wiring plus an emergency parallel (the old negative switch), dedicated & isolated start and house banks, full isolation of each bank and full cross over and an ACR etc...