Abstract: A bi-directional system for ensuring that a ground connection is made in a three-wire conductor system including a line "hot" conductor, a line neutral conductor, and a ground conductor includes a circuit for generating direct current potential related to the potential difference between the line "hot" conductor and ground and a second circuit for generating a direct current potential related to the potential difference between the line "hot" conductor and ground. A circuit including a male plug for insertion into a female receptacle includes a first prong for coupling alternatively to the line "hot" conductor or the line neutral conductor, a second prong for coupling alternatively to the line "hot" conductor or the line neutral conductor, and a third prong for coupling to the line ground conductor.

Abstract: A hand-held grinder including a motor, a motor output shaft and a grinding tool mounted on the motor output shaft. Water is supplied from a source through a port into a sealed annular chamber surrounding the output shaft. A bore extends concentrically through the shaft between a point adjacent the annular chamber and the end of the shaft remote from the motor. Communicating bores extend radially through the shaft and through a collar keyed to the shaft from the concentric bore to the annular chamber. Additional bores, adjacent the end of the shaft remote from the motor, provide communications between the concentric bore and the outside of the shaft. Preferably, the sum of the cross-sectional areas of these last-mentioned bores is relatively less than the cross-sectional area of the concentric bore. Water dispensed through these communicating bores is atomized by rotation of the motor output shaft and grinding tool.

Abstract: A compact apparatus for removing harmful particulate contaminants from the air in a work space includes a nozzle for atomizing water. The nozzle is connected to a supply of compressed air and to a supply of water, e.g., an ordinary water tap or storage tank. The apparatus also includes a metal ring and a power supply coupled to the ring to charge atomized water inductively as the water is expelled from the nozzle. A collar supports the ring in fixed, spaced-apart relation adjacent the nozzle. The collar is constructed, at least in part, from a non-conductive plastic, such as nylon, to avoid shorting of the power supply. Additionally, the collar includes a compressed air supply passage for introducing a stream of air into the collar. This air flows past the nozzle and the ring to prevent accumulation of water on the ring and collar and the electrical shorting which may result therefrom.

Abstract: A hand-held grinder including a motor, a motor output shaft and a grinding tool mounted on the motor output shaft. Water is supplied from a source through a port into a sealed annular chamber surrounding the output shaft. A bore extends concentrically through the shaft between a point adjacent the annular chamber and the end of the shaft remote from the motor. Communicating bores extend radially through the shaft and through a collar keyed to the shaft from the concentric bore to the annular chamber. Additional bores, adjacent the end of the shaft remote from the motor, provide communications between the concentric bore and the outside of the shaft. Preferably, the sum of the cross-sectional areas of these last-mentioned bores is relatively less than the cross-sectional area of the concentric bore. Water dispensed through these communicating bores is atomized by rotation of the motor output shaft and grinding tool.