An Essential Guide for Facility Owners, Insurance Adjusters, and Legal Teams
After a catastrophic electrical cable failure, the immediate priorities are safety and service restoration. But once the smoke clears, the critical phase of investigation begins. For facility owners, insurance adjusters, and legal teams, determining the root cause analysis of the cable damages is paramount for financial recovery and preventing future incidents.
This is the work of forensic engineering. The investigation goes far beyond a simple visual inspection of the failed power feeder. It is a meticulous process of evidence gathering and advanced diagnostics. While the cause of failure can range from installation errors to manufacturing defects, the investigation often finds its most critical evidence in a document from day one: the original commissioning report.
This guide explains how a forensic engineer dissects the evidence to uncover the true story behind a cable damage incident.
The Commissioning Report: A Forensic Engineer’s Starting Point
A commissioning report is supposed to be a clean bill of health for a new power feeder. However, in a cable damage investigation, it frequently becomes the primary evidence of pre-existing conditions or negligence. Standard, “checkbox” commissioning often misses latent cable damages that later lead to failure.
An expert electrical failure analysis revisits this initial report, looking for critical red flags:
- The “Passing” Insulation Test: A report may show a “Pass” with 125 megohms on a medium voltage cable that, when healthy, should read over 800 megohms. To a forensic expert, this “pass” is evidence that the cable was already compromised at handover. We use advanced diagnostics like Polarization Index (PI) testing—a standard of care often skipped by contractors—to prove the insulation was contaminated from the start.
- Data Without Context: Often, a contractor provides a simple sheet of readings. This is not a valid test report. A forensic investigation will scrutinize it for missing information that is crucial for a claim:
- Environmental Conditions: Were tests done on a hot, humid day? This can invalidate the readings.
- Equipment Calibration Certificates: Were the meters accurate?
- Interpretation Notes: A lack of analysis suggests a “checkbox” mentality, not professional due diligence.
Beyond Commissioning: A Comprehensive Failure Investigation
While a flawed commissioning report is a powerful piece of evidence, a complete root cause analysis investigates all potential causes of the electrical cable failure. The same advanced diagnostic tools that should have been used in commissioning are now deployed by the forensic engineer to pinpoint the exact failure mode. This includes:
- Time-Domain Reflectometry (TDR): To precisely locate the fault along the cable’s length.
- Very Low Frequency (VLF) & Tan Delta Testing: To assess the overall health and aging of the cable insulation that remains, determining if the failure was an isolated incident or a systemic problem.
- Physical and Material Analysis: Examining the failed cable section for evidence of installation errors (e.g., excessive pulling tension, improper bending radius) or manufacturing defects.
Conclusion: From a Sheet of Readings to a Defensible Verdict
A sheet of numbers from a contractor is not a cable damage investigation. It is a potential piece of evidence that requires expert scrutiny. A true forensic engineering investigation provides a complete, defensible conclusion by analyzing all the evidence—from the original commissioning report to the physical cable itself. This process empowers you to move beyond the initial incident with a clear understanding of the root cause, forming the indisputable foundation for insurance claims, legal action, and preventing a recurrence.
From Incident to Resolution
When a cable failure disrupts operations, the path to financial recovery depends on a clear, defensible failure investigation. Our forensic engineering experts specialize in dissecting the complex evidence trail—from the initial commissioning report to the physical point of failure.
To understand the proactive commissioning steps that can prevent these failures from happening in the first place, please see our companion article: The Commissioning Checkbox: Your Facility’s Biggest Blind Spot
If you are managing the aftermath of a cable damage incident and need to understand the “why,” Contact us for a confidential case review. We provide the expert analysis required to turn complex evidence into a clear resolution.
