An unexpected loss of power can have a significant effect on business, especially in a mission critical environment. Isolating an electrical fault condition to the smallest area possible is essential in providing the most reliable electrical distribution system with maximum uptime for your facility. Expensive electronic distribution protection equipment is not worth the extra cost unless a proper protective device coordination study is provided by an experienced electrical engineer. A properly coordinated system will limit an electrical fault to the nearest upstream protective device. After a one-line diagram of an electrical distribution system is completed and the brand and model of the protective devices are selected, an overcurrent protective coordination study can be completed. Protective devices can consist of both fuses and breakers. Evaluating the merits of choosing to use fuses or circuit breakers is beyond the scope of this article. The primary focus of this article is adjustable trip circuit breakers as the protective device.