The paddle switch may be used as either a high or low level limit switch. It is easily mounted from above, or through a vessel wall.  A small electric motor drives a paddle which rotates freely in the absence of material. When the paddle is impeded by the presence of material, a microswitch actuates an alarm signal. As soon as the paddle is completely stopped from rotating, power to the motor is cut, thereby extending motor life. After the material level falls, the motor is returned to its normal position and the paddle begins to rotate again.