The National Electrical Manufacturers Association (NEMA) published NEMA ESM1-1 2019 Electrical Submeter—General Requirements and NEMA ESM1-2 2019 Electrical Submeter—Active Energy Accuracy. NEMA
ESM1-1 covers general metrological requirements (accuracy) and associated testing for electrical energy submeters detailing energy use. NEMA ESM1-2 covers metrological requirements and associated testing for AC meters rated at not more than 1,000
V that measure active energy used in electrical energy submetering applications.