Where does a solid state liquid level control obtain its ground connection if there is no terminal for it?

A solid state liquid level control typically obtains its ground connection from the mounting screw connections when there is no dedicated terminal for it. The mounting screws often serve a dual purpose, securing the device to a metal enclosure or panel while also providing a pathway for electrical grounding. This is crucial for safe operation, as grounding helps to prevent electrical shock and reduces the risk of electrical faults by directing stray currents safely to the ground.

While the power supply, water, and control panel could theoretically provide grounding connections, they are not reliable or safe alternatives. Power supplies may not offer a dedicated ground point, and using water as a ground is hazardous, as it can lead to erratic operation or safety issues. Grounding through the control panel might not ensure an adequate ground due to potential isolation from the actual earthing system. Hence, utilizing the mounting screw connections is the standard practice for establishing a reliable ground connection in these types of controls.