The purpose of this manual is to familiarize qualified personnel with problem areas of supplying electrical power to automated data processing (ADP) systems. Special emphasis is placed on areas most often overlooked or misunderstood by experienced designers and personnel responsible for maintaining an outflow of quality data from an ADP installation. ADP systems are highly reliable, but will on occasion malfunction and because of their complexity will require the services of highly skilled personnel to correct and maintain the systems. This manual covers many inter-related aspects of an ADP installation in regard to the electrical and life-safety systems. This manual will review the systems found in the typical data center, and is not intended to provide the detailed level of understanding where arithmetic and other more advanced mathematics are required to describe or explain a given function.