The purpose of this Code of Practice is to provide a reference to practitioners on the safe, effective and competent application of electrical energy storage systems. It also provides an understanding of the common terms and operating modes of electrical energy storage systems. Building on the IET's technical briefing, this Code of Practice will also provide detailed information on the specification, design, installation, commissioning, operation and maintenance of an energy storage system. The scope covers all types of electrical and electrochemical energy storage systems; integration into low voltage power systems; industrial, commercial and domestic applications and systems aligned with existing standards, regulations and guidance. The audience for this Code of Practice includes renewable energy developers, electrical contractors and building technicians, M&E and design consultants and energy and facility managers. It would also appeal to manufacturers, building control, fire services, insurance companies and anyone involved in research and development in this area.