Overhead transmission lines experience the highest frequency of faults due to their direct exposure to environmental conditions. Wind, lightning, ice, vegetation contact, animals, and pollution all contribute to transient and permanent fault conditions on overhead conductors. Unlike underground systems, overhead lines are not shielded from weather-related events.
NETA Level 2 technicians must understand fault likelihood when interpreting protective relay operations, breaker trips, and event records. Many relay schemes are designed with reclosing logic specifically because overhead line faults are often temporary. This understanding supports proper commissioning, testing of protective devices, and evaluation of fault-clearing performance.