Abstract: An electric safety switch assembly for an internal combustion engine, the engine being provided with an oil pump to supply oil to a oil line for lubricating the engine, and an electric operated starter for the engine, including a manually operatable starter switch or closing an electric circuit to the starter and an electric circuit-breaker in the form of a oil pressure switch positioned between the manually operated switch and the starter which is normally held closed when there is no oil pressure in the oil line. The pressure switch is adapted to open the electric circuit when the engine is rotated sufficiently to cause the oil pump to produce a predetermined pressure in the oil line.