This part of IEC 62257@ which is a technical specification@ specifies the general requirements for the design and the implementation of a user's installation. This part of IEC 62257 applies to single phase user's electrical installations with maximum power of 500 VA@ in Decentralized Rural Electrification Systems (DRES). NOTE For installations above 500 VA in decentralized electrification systems@ IEC TS 62257-5 applies. This part of IEC 62257 is applicable to installations supplied by an a.c microgrid (120 V or 220 V or 230 V or 240 V) and to installations encompassing their own single-unit a.c. micropower plant (120 V or 220 V or 230 V or 240 V) or d.c micropower plant (12 V or 24 V). The part of IEC 62257 applies neither to the electric power production and distribution installations described in the clauses concerning micropower plants and microgrids@ nor to user electrical equipment. It details the rules governing the design and construction of consumer??s electrical installations for the purpose of ensuring the safety of persons and property@ and satisfactory operation in accordance with the purpose for which the installations are designed. It applies to new installations and modifications of existing installations.