The house 120 volt AC system can provide AC power to the van duplex plugs from 3 sources.

1. Shore power from a 3 prong male 15 amp plug that is installed below the driver's door.
2. From a vehicle 12 volt powered 1000 watt pure sine Samlex inverter.
3. If neither source of shore power is available then the house battery can be used by the Magnum MMS1012 inverter/charger/transfer switch to provide 120 volt AC power to the van duplex plugs.

Two selector switches are used to select where shore power is sent.  First switch selects either real shore power or "shore power" from the vehicle powered inverter.  The second selector switch selects where the power is sent.  It can be sent to the house Magnum inverter or to the 625 watt electric water heater or to the 750 watt Broan Model 124 electric baseboard air heater. There is a two pole 15 amp circuit breaker between the two selector switches.

When the 120 volt power is sent to the Magnum house inverter it first passes through a GFCI duplex plug that is located between the selector switch and the house inverter.  The Vitrifrigo 12 volt DC/120 volt AC refrigerator is plugged into that GFCI duplex plug.  That way anytime 120 volt AC power is available the refrigerator will run on AC instead of DC from the house battery.

The 120 volt AC power then goes to the Magnum house inverter/charger/transfer switch.  The inverter has a relay that automatically transfers the power through the inverter to the van duplex plugs.  Inverter does this without being turned on.  If shore power is not available the house Magnum inverter can be turned on to provide 120 volt AC power from the house battery.  The house inverter is turned on only when 120 volt power is needed.  If house magnum inverter is left on overnight without any loads it will use up 6% of the house battery capacity just idling.

After the inverter there is a two pole 15 amp circuit breaker before the first duplex plug.  The first duplex plug is a GFCI outlet.  From the GFCI duplex outlet there is a string of regular outlets.  Only one 120 volt AC circuit. There are 3 regular duplex plugs after the GFCI plug and one female extension cord .