How are Water Pump Relay Switches Wired & Controlled?
Electrical power, either 120V or 240V, is brought into the relay switch from the electrical panel and is connected to one side of an internal relay switch inside the box. Wiring to the water pump, usually a submersible pump located inside the well, is connected to the other side of the relay switch.
A separate pair of wires will run from the relay switch to the pump pressure control switch. (See that little gray box at the lower end of the conduit below the larger, wall-mounted gray pressure switch box?).
When the pump pressure control switch detects that the water pump should turn on, a light-duty switch inside of the water pump pressure control switch senses this pressure drop and turns on the heavy-duty electrical relay switch inside of the wall mounted pump relay.
The wall mounted relay thus is sending power to the water pump.