Cable Root Cause Failure Investigation

A local distribution company (LDC) in Ontario experienced a cable failure installed in a new subdivision area, with no abnormal operating conditions or prior failures observed. To support the LDC we conducted a detailed evaluation of over 100 feet of cable involving laboratory testing, analysis and dissection to determine the failure mode, and provide recommendations for corrective actions.

Based on our findings, the most probable cause of failure was concluded to be cable jacket rupture during cable pulling, resulting in moisture ingress, which eventually migrated into the semicon and the insulation, causing the cable insulation failure.  

All electric utilities have extensive systems of power cables. With these aging systems, failures are becoming more common leading to power reliability problems and unexpected costs. That is why not only did we provide recommendations to the LDC in terms of how to manage the cable procurement process but we also provided recommendations on how to verify the quality of future cable installations through electrical testing at commissioning, thereby avoiding premature failures.  

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