Good maintenance regimes do not happen by accident: they need careful planning, proactive management and comprehensive reporting. This Guide has been prepared for all those involved in maintenance; electrical technicians, maintenance managers and also office-based design staff. The document provides updates to the original text where necessary and introduces additional items and areas for consideration as part of a maintenance programme. Appendix B in the original document now forms a new Section to provide greater focus on the practical aspects across a wide range of electrical installations. Additional topics have been added, and the format revised to make it a more practical tool for technicians and supervisors alike. A good maintenance regime has an increasingly significant role in a more sustainable world where correctly maintained electrical systems keep operating at their maximum energy efficiency for longer and are disposed of correctly at the end of their lifecycle.