Why separate power switches on the two banks' grounds ?

[Sven_G]

Last summer I spent a lot of time trying to figure out why there were two power switches in the head and one regular 0 - 1 - 1+2 - 2 Guest switch under the helm. After all there are just two battery banks.

Since we just replaced the batteries I had a chance to trace the power circuits and I found out that the two switches in the head each break one ground connection for the two banks. The Guest switch does what you'd expect, controls the positive connections and combines them as needed.

I've never seen a setup like this and wonder if there is a specific reason for this wiring redundancy ? I certainly don't mind the extra control but at the same time KISS is usually a good approach.

Any ideas ?

Thanks,

[DougSea]

Well...I have no idea.

I did some searching and came across this web site: http://boatwiringadvice.com/

He seems to post fairly well thought out answers to his readers marine electrical questions. I'd post your question from above there if you don't get any decent responses.

[RobS]

galvanic isolation?

[Sven_G]

Thanks for the suggestions. I did forward the question to the Boat Wiring Advice folks too.

[DougSea]

One thought. Are the switches somewhat hidden? Could be a "security" system. Someone gets into the boat, turns on the battery switched, and nothing happens!

That's the best I can do right now. I'll be interested to hear if the Boat Wiring site has anything better.

[Tree]

Our old boat had a similar set up - the main switch was for the two batteries in the engine bay and we had another switch in the cabin that was for isolating the auxiliaries and electronics.