This International Standard provides a classification of NILM sensing devices for use in NILM systems, according to the state of the art of NILM technologies. The classification of NILM analytics and NILM systems, as well as performance indicators for NILM systems, can be considered in the future. NILM systems produce estimated disaggregation into energy usages. When accurate measurement and analysis of energy consumption and/or other electrical parameters is needed (e.g. for monitoring the electrical installation), systems based on standardized measuring devices (e.g. PMD, PQI or meters) are used. NOTE Standardized measuring devices have guaranteed accuracy over a specified range and have limited deviations in presence of influence quantities (temperature, frequency deviations& ) in addition to safety and constructional requirements. See Annex C for more information.