My original house system solenoid drew a current of 3 amps when turned on by the salesman switch at the front entrance. This older style solenoid used current to hold in a continuous duty spring loaded contact to bridge power from the house batteries to the 12v house system. This added a power draw to the house batteries depleting the available power to little to no use. The original solenoid was upgraded to a zero draw when on Intellitec Battery Isolation Solenoid. The project below shows the details of changing the salesman switch and house solenoid to the new system. The manuals are included below. The links may die over time but a search on the net should find all the relevant materials should that happen.