This Guide identifies and discusses security issues related to human intervention during the construction, operation, (except for natural disasters) and maintenance of electric power supply substations. It also documents methods and designs to mitigate intrusions. Access to electric supply substations by unauthorized personnel is an increasing problem for the electric industry. These intrusions may result in loss, damage, and mis-operation of equipment and facilities. This Guide will present various methods of and techniques presently being used to mitigate human intrusions as identified in an industry survey. New IEEE Standard - Inactive-Reserved. Security issues related to human intrusion upon electric power supply substations are identified and discussed. Various methods and techniques presently being used to mitigate human intrusions are also presented in this guide.