Covers a.c. motor capacitors of a type having a dielectric of paper and plastics film and with rated a.c. voltages of up to 660 V, and the electrolytic type with rated voltages of up to 500 V, intended, in each case, for connection to the windings of asynchronous motors, designed for a single phase supply having a frequency of 50 Hz and suitable for operation at altitudes not exceeding 2 000 m. Specifies the preferred values of rated capacitance, rated voltage and operating temperatures, and the requirements for the variation of capacitance with temperature, tangent of the loss angle, sealing, damp heat resistance, self-healing, container disruption, insulation resistance, resistance to high voltage, endurance and abnormal operation.