Service life of up to five decades may be expected at the high-voltage power components. This life-time is the result of a carefully controlled design and production process at the manufacturer as well as the result of the maintenance policy of the power supply utilities. Quality management systems, certified according to ISO 9000 or QS 9000, are state of the art at most of the manufacturers. At present there are some utilities which are considering introducing certified environmental management systems in compliance with ISO 14000 or EMAS-VO, but there are poor reports of the implementation of a certified quality management. Most of these quality management elements are based on an individual preventive and corrective maintenance policy. Differing methods are used for inspection, monitoring and dielectric diagnosis. Finally this strong failure and fault analysis leads to a well documented information system being the basis for future order and the required specifications. A key point is the confidence between utility and manufacturer and the silent agreement to exchange failure analysis and long-term experiences in detail.