Abstract: Parallel infrared beams are directed along opposite edges of an electronic scale which has its weighing platform mounted flush with a supermarket check-out counter. In the event that an object being weighed overhangs the scale and contacts the counter, it will break one or more beams. Means are provided for detecting the interruption of a beam and a disable control signal is generated. Normally, an electronic cash register is connected to an output of the scale for computing the price of a weighed object. However, when the disable signal is generated, communication between the scale and the electronic cash register is disabled, thereby preventing computation of an incorrectly weighed object.