IEC 62052-11 contains the general requirements, tests and test conditions that apply to electricity metering equipment. It is the foundation document of the metering equipment series: the part 2 documents add the specific requirements for each accuracy class and each technology, while this part provides the common framework. The standard defines the classification of metering equipment by accuracy class, by the type of connection, by the number of elements and by the internal or external construction, and it establishes the reference conditions under which measurements are made and the limits of variation that apply when the conditions depart from the reference. It specifies the requirements for construction, for markings and for the enclosure, and it sets out tests for insulation, for the effects of the supply voltage and frequency, for the influence of self-heating, for the variation of the accuracy with the load current and the power factor, and for the immunity of the meter to disturbances, including electromagnetic compatibility tests and the influence of conducted and radiated disturbances on the metering registers.