Alternating Relay. In the initial OFF state, all three switches are open, the Duplex Pump Controller is in the LOAD 1 position, and both loads are off. No action happens with the Controller or either load when the OFF switch closes. When the LEAD Switch closes, LOAD 1 turns on. When the LAG Switch closes, LOAD 2 turns on. Both loads remain on as long as all three switches are closed. When the LAG Switch opens, LOAD 2 remains on because the Duplex Controller simulates the function of an auxiliary contact. When the LEAD Switch opens, LOAD 1 remains on for the same reason. When the OFF Switch opens, both LOAD 1 and LOAD 2 are turned off simultaneously because all voltage is removed to both loads. The Duplex Controller toggles to the LOAD 2 position. The entire cycle is then repeated, but with LOAD 2 energized first followed by LOAD 1. Combines functions of alternating relay, control relay and auxiliary contacts in one unit - saves money. Offers Sequence On - Simultaneous OFF (S.O.S.O.) Operation with three float switch inputs. Protects against failures of both OFF and LEAD switches. Low profile selector switch for normal alternation or to lock either load to be ON first. 2 LEDs indicate load to energize first.