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Electrical Cable Failure: The Trillion Dollar Question

Dec. 6, 2016
A trillion dollars is likely a conservative estimate when you consider the magnitude of the power cable issues in the U.S.

A trillion dollars is likely a conservative estimate when you consider the magnitude of the power cable issues in the U.S. It has been known for some time that the cable systems in the U.S. have reached and in many cases exceeded their life expectancy.  Let’s face it, wholesale replacement of an underground cable installation is expensive, time consuming and many times results in off hour scheduling and clearances requiring customers to be without power during reconnection of power to theinstallation.

A lot needs to be said about the aging power cable issue and much has been published involving the failures in cables, splices and terminations.  Analysis clearly states the issues with service aged polyethylene (XLP) concentric neutral cables that were the main stay for utility installations in the 60’s through 80’s.  These cables, thought to be the answer to many installation issues, turned out to be a “major disaster,” considering reliability and replacement costs.  Much of this type of cable was of the concentric neutral (CN) design and had no jacket to protect it from the environment or from installation damage.  Enter “water,” the culprit of the century where XLP insulation is concerned.  In defense of the manufacturers and utility engineers, no-one knew what was to ensue between water and Cross-Linked Polyethylene insulation i.e. the formation of water trees in the insulation.  Since this condition is slow to develop and much slower to lead to total insulation failure via the formation of full blown electrical trees, it was not evident early on that these 40 yr. cables would only last half of that time, with many only lasting 10 to 15 years before failing.  Tree Resistant Cross Linked Polyethylene (TRXLP) came on the scene in the late 90’s for most utilities and this treeing issue will largely go away over time for the most part.  Most utilities are keenly aware of this issue today and are in the beginning or middle stages of providing “high tech” rejuvenation processes that extend the cables life or are planning complete replacement of these cables in bulk quantities at significant costs.

Utilities and industries with large cable systems are currently at various stages in addressing the issues with service aged XLP cables.  Two topics keep coming up in the industry discussions that are very important in addressing this major concern.  One is “Condition Based Maintenance” and the other is “Diagnostic Testing”.  Both of these topics are extremely important, considering the costs incurred with cable replacement.  The third item is the “human factor.”

Proper training in the areas of Cable Splicing & Terminating, Cable Fault Location & tracing and Cable Testing & Diagnostics is critical in controlling future issues and spiraling replacement costs associated with electrical cable system failures.

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