Interference
Choose the electrical behavior first. The hub routes; the canonical resources govern.
AC Interference is the route for AC voltage/current, power-line coupling, AC-corrosion assessment, personnel AC exposure, fault/lightning relationships, and AC mitigation/monitoring.
DC Interference is the route for externally forced DC current, source-correlated potential/current response, pickup/discharge, foreign rectifiers or other DC sources, bond-current behavior, and DC mitigation/verification.
If the issue is a normal spatial CP current/potential decay question without external-source evidence, use Current Distribution & Attenuation. If all you have is one unexplained potential or voltage change, collect source/state/path evidence before assigning an interference mechanism.