Originally Posted by Jkidd
Mechanic told me to put both switches ........ to off when hooked to shore power.
Your mechanic is an idiot!!!
If you turn off your House battery bank you will not have lights or pressure water pump (water from faucets), even when you are on shorepower. If you have an electric flush or vacuflush head you will also not be able to flush the toilet.
On shore power, the shore power supplies power to the battery charger, the battery charger keeps amperage flowing the batteries. All the 12VAC systems continue pulling from the batteries regardless of whether you are connected to shorepower or not.