A major challenge in maintaining underground utility lines is the evasive nature of cable faults. Damages in the cable could go unnoticed for much longer than in exposed overhead lines. The safety risks and financial drawbacks are steep because faults could eventually cause voltage breakdown. Early detection of such faults should always be a priority.
Causes and Types of Underground Cable Faults
Different elements cause the breakdown of an active underground cable. The most common faults are usually caused by one of the following:
- Sheath damage
This is also called earth fault. The cable screen comes in contact with the soil and external elements after the protective sheath is breached. Chemical reactions, crystallization, and vibrations are the usual culprits.
- Phase discontinuity
This happens when multiple conductors in a multi-cored cable come in contact with each other. Short circuit faults occur when individual insulators for the conductors come apart and the different levels of resistance cause voltage discontinuity in the line.
- Wire breaks
Wire breaks or open circuit faults is often caused by mechanical stress or vibrations. Open circuits could cause treacherous voltage disruptions in underground cables.
A resistance-testing device called megger can typically locate wire breaks, short circuits, and earth faults. Meggers are often used together with regular cable locators and should be part of any underground location toolkit. It is a small investment to pay for detecting faults as soon as possible and avoiding future mishaps and injuries.