This European Standard specifies methods of measurement of electrical power consumption, and the reporting of results, for external power supplies. This standard is applicable to external power supplies with a rated input voltage within the range 100 V ac to 250 V ac having a single output with a rated output power not exceeding 250 W and a rated output voltage not exceeding 230 V a.c. or 325 V d.c. The output voltage may be either at a fixed voltage, or at a voltage which is user selectable, or at a voltage that is automatically selectable by the external power supply so as to be compatible with one or more product-loads.