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General Provisions

4.0.1　The construction and acceptance scope of earth electrodes covers the construction，interim acceptance，test before energizing and as-built acceptance of earth-rock work，earth electrodes welding，carbon bed laying，cable pits and manholes.This specification is prepared to guarantee the construction and installation quality of earth electrodes in±800kV and below DC transmission and ensure that±800kV and below DC transmission systems can operate safely and reliably under design conditions.

4.0.2　The construction，installation and acceptance of overhead current dividing system in earth electrodes in±800kV and below transmission systems shall comply with GB 50233 or GB 50173；installation and test of reactors shall conform to GBJ 148 and GB 50150.

4.0.3　The construction and installation of earth electrodes in±800kV and below transmission systems shall be performed in accordance with the approved design documents，design and construction drawings jointly reviewed by relevant departments and corresponding construction organization design，working instructions（or technical measures）.

4.0.4　The types，specifications，models and performances of raw materials，equipment and devices employed in the project shall be consistent with the design requirements and the current national technical standards of corresponding products（unless otherwise specified in design documents or construction contracts），and if no current standard is available then，the relevant IEC standards or enterprise standards.Also，they shall meet the technical conditions for order placement，and shall be completed with quality certificates.

4.0.5　The state-of-the-art technologies and techniques involved in the construction and installation can only be used after they are demonstrated to comply with this specification through tests and verifications.

4.0.6　The measuring and checking equipment（e.g.，instruments，gauges and measuring tools）used in construction and installation shall be qualified products within their validity period.