Revision Standard - Superseded. This IEEE Standars product is part of the Color Books family. The design of reliable industrial and commercial power distribution systems is important because of the high cost associated with power outages and their significant impact on society. It is necessary to consider the cost of power outages when making decisions for new power distribution systems. It is also necessary to have the ability to make quantitative "cost-versus-reliability" trade-off studies. The IEEE Gold Book provides credible data concerning equipment reliability and the cost of power outages so that these trade-off studies can be conducted. The purpose of the IEEE Gold Book is to provide sufficient information so that reliability analysis can be performed on power systems without requiring cross-references to other texts. Information included in the book is the result of extensive surveys of reliability of electrical equipment in industrial plants and the costs of power outages for both industrial plants and commercial buildings. The reliability surveys provide historical experience to those who are not able to collect their own data. The IEEE Gold Book covers many aspects of reliability analysis. The basic concepts of reliability analysis by probability methods, fundamentals of power system reliability evaluation, the economic evaluation of reliability, and cost of power outage data are included in the book. Reliability data, as well as electrical preventive maintenance for different types of equipment, are provided. Some concepts of emergency and standby power, such as reliability compliance testing, are also included in the IEEE Gold Book. The book also focuses on the improvement and evaluation of reliability in existing facilities. Voltage sags, and a methodology for estimating the frequency of these sags, are also discussed.