The F263 Series Float Switch controls water levels to within approximately 1/2 in. (13 mm).
When the liquid level falls approximately 1/2 in. (13mm) below the height at which the switch is installed, the switch closes the red contact (common) to the blue contact. See Figure 1 and Figure 2.
When the liquid level in the tank rises to the height at which the switch is installed, the switch closes the red contact (common) to the yellow contact. See Figure 1 and Figure 2.
Figure 1. F263 Float Switch Setup
Figure 2. F263 Float Switch Action