Overhead Distribution Line Construction
Foundation
Know the components of an overhead line: poles, crossarms, insulators, conductors, guys, anchors, and the hardware that connects them. Understand pole classes and the meaning of pole strength, and why guys and anchors are needed to resist unbalanced tension at corners and dead-ends. Span length, sag, and tension are related: for a given conductor and span, more tension means less sag.
Concepts to master
Conductor types and their tradeoffs: AAC, AAAC, ACSR, and copper, with ampacity depending on material, size, and installation. Understand insulator types and the purpose of tie wire and armor rods. Know the purpose of a neutral on a multigrounded wye system and why it is grounded at intervals. Understand the difference between a corner pole, a tangent pole, and a dead-end structure, and which requires guying. Clearance to vegetation and the concept of a safe working zone near energized lines matter here.
Traps
Questions often assume guys are optional at dead-ends, or confuse ampacity with short-circuit withstand. Another trap is mixing up sag and tension direction - increasing tension decreases sag.
Rule of thumb
Any structure carrying unbalanced conductor tension - corners, dead-ends, taps - needs guying or equivalent strength.
Worked example
A dead-end pole carrying three conductors on one side experiences a large unbalanced pull; a guy and anchor installed opposite the conductors transfer that load to the ground.