[Guy]

Curiosity got the best of me today, I have been aware of this switch for     a long time. I would really like to understand it, and how it relates to the inverter. This switch is located behind a false wall in a closet directly above the incoming street power. (Hint #1)  

I am "assuming" that if no 120 volt street or generator power is available, this relay having no coil current, allows both 120 volt circuits to energize the two inverter circuits in the coach?