New IEEE Standard - Superseded. Electrical faults on transmission and distribution lines are detected and isolated bysystem protective devices. Once the fault has been cleared, outage times can be reduced if thelocation of the fault can be determined more quickly. This guide outlines the techniques andapplication considerations for determining the location of a fault on ac transmission and distributionlines. The document reviews traditional approaches and the primary measurement techniques usedin modern devices: one-terminal and two-terminal impedance-based methods and traveling wavemethods. Application considerations include: two- and three-terminal lines, series-compensatedlines, parallel lines, untransposed lines, underground cables, fault resistance effects, and otherpower system conditions, including those unique to distribution systems.