Submersible pumps use float switches to engage the pump. The float switch moves with the tank’s water level. This movement determines when the pump turns on and shuts off. In this segment, we’ll discuss the correct way to hardwire a float switch to a submersible pump in order to achieve automatic operation.
The diagram below references a 115V pump and wiring. Over 95% of aerobic septic systems use 115v rather than 230v. We recommend using a “piggy-back” float switch or control panel to operate 230V pumps
DO NOT USE THE METHOD DESCRIBED BELOW FOR 230V PUMPS.
In 115V wiring, you are dealing with 3 legs: Hot, Neutral, and Ground/Green wire. The pump will have these three wires and the incoming power supply will have these three wires. The neutral wire from the panel will connect directly to the neutral wire from the pump. The ground/green wire from the panel will connect directly to the ground wire from the pump. Now you are left with the hot wire from the panel and the hot wire from the pump. The float switch has two legs. One leg of the float switch will connect to the hot wire from the panel and the other leg will connect to the hot wire from the pumps. Please note: Most float switches have a white and black wire, which means you will most likely have a white to black connection. This is perfectly normal and the correct way to do it. Once these connections are made, you’re ready to turn the power back on and the submersible pump should operate according to the position of the float switch. Before setting the pump in the tank, test the float switch. Do this by lifting up the float switch and verify that the pump engages.