There are actually two pumps. The back-up system is called "Ace in the Hole". The lower pump is a normal 120v sump pump. About a foot above it is the 12v pump. The 12v pump serves two purposes. The first one is obvious, power failure. The second is in case the first pump can't keep up with the water seepage since the building is in a very wet area. It has saved the day more than once!!!
WireWrestler
