Originally Posted by chris856
I've wired a few septic systems using a line voltage double float switch and have no problem on how to wire and test them.The one thing I am a little fuzzy on is how exactly they work.
I know when the tank level rises high enough and raises the first float nothing happens.
When the level gets high enough to raise the second float, the circuit closes and the pump starts running and draining the water.
The water level falls enough to lower the top float and the motor still runs.
The motor stops running when the the tank level is low enough that both the top and bottom float are down.
The one thing I don't know is what keeps the circuit closed after the top float goes down.
This is a basic switch and uses no control wires.
The first floats only purpose is to pull out a relay- sort of like a stop button. When it raises it does nothing but when it drops it pulls out a relay that was energized by th on float. So you have a start and stop switch.
I see Jlarson beat me to it.