This guide documents methods and designs to mitigate interruptions and equipment damage resulting from animal intrusions into electric power supply substations@ thereby improving reliability and minimizing the associated revenue loss. Purpose Intrusion by animals into electric supply substations has been a problem experienced by most of the electric utility industry. The costs associated with outages caused by animals continue to escalate. Although animal problems differ in nature geographically@ the damage to equipment@ interruption of or loss of service to customers@ and safety problems encountered by operating personnel result in the same general concerns. This guide identifies various animals@ the problems they cause and mitigation methods. Further@ it recommends criteria for applying mitigation methods@ documents survey-reported effectiveness of various methods and recommends factors for evaluating effectiveness of methods once they are applied.