Sponsored by: FLIR

Potentially Lethal Hotspots

Thermography is a proven technology for finding many types of defects within electrical systems. While infrared inspections can assist in PdM efforts, they can also point out a potentially lethal condition that can lead to electrocution and death.

Many AC electrical devices are wired with a grounding conductor. Ungrounded metallic structures and devices can become unintentionally energized if a bare circuit conductor makes contact with the subject structure. In ungrounded structures, improper wiring or defective/deteriorated insulation can allow the structure to become energized up to full circuit voltage. In such cases, anyone touching the energized structure may be electrocuted or fatally injured. One such fatality occurred in May, 2003 when a nine year-old boy made contact with an energized light pole in Columbus, Ohio.

On at least three separate occasions in 2003, thermographers have found evidence of energized structures with a thermal imager. All three findings involved outdoor metal light poles which exhibited inexplicable hotspots where the pole was bolted to the concrete footing. In the Columbus case, a nearby steel fence post also exhibited an inexplicably hot base where bolted to the concrete sidewalk.

For reference we have included thermal images of one of the aforementioned light poles. We urge thermographers to be on the lookout for this potentially lethal thermal anomaly and to immediately notify appropriate personnel should you detect evidence of this condition in the future.

Thermal images show base of metallic light pole operating
in excess of 180ºF due to ground fault condition.

Infrared inspection of electrical systems is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.