The Insurer's One-Page 'Pass' Report
A Level II thermographer surveys a 12-panel motor control centre for an insurer. The deliverable is a PDF with 12 rainbow-palette JPEG images pasted into a word processor. Each image has a spot temperature, but there is no temperature scale, no emissivity, no reflected temperature, no distance, no load current, no ambient temperature, no camera or lens model, and no date/time. The conclusion reads: 'All panels passed; maximum temperature 63 °C, below the 70 °C limit.' One image shows a 22 °C difference between a line-side lug and the busbar, but the thermographer writes that it is 'probably reflection'. The client asks you to review the report before accepting it.
1. Identify the report deficiencies and explain which ones make the pass conclusion indefensible.
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Deficiencies include: no radiometric data (JPEG only), no temperature scale or palette span, no emissivity or reflected temperature, no distance/lens/spot size, no load current, no ambient temperature, no camera model or calibration date, no date/time, no stated acceptance standard or severity criteria, and no anomaly table. The rainbow palette can also obscure subtle gradients if the span is not fixed and documented.
The pass conclusion is indefensible because the 70 °C limit is applied without load and without emissivity. A 63 °C reading at unknown load and unknown ε cannot be compared with an absolute limit. The 22 K difference is a significant anomaly, yet it is dismissed as 'probably reflection' without any test. The report gives the insurer no way to verify the measurement conditions or the conclusion.
2. What must a defensible Level II report contain, and what should be re-done?
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A defensible report should contain: client and site identification; date and time; thermographer name and certification level; camera, lens and calibration information; environmental conditions; load current and operating state; emissivity and reflected temperature settings; distance and spot size; the acceptance standard and severity criteria; an anomaly table with location, apparent and corrected temperatures, severity and recommendation; thermal and visual images with a readable temperature scale; limitations; and a signature.
The survey should be re-done or the raw radiometric files re-analysed if they exist. If only JPEGs were saved, a re-scan is required for any quantitative conclusion. The 22 K anomaly must be re-examined and classified. A Level II can perform and report the survey, but should not certify a pass on data that cannot support it; a Level III review is appropriate if the insurer requires an acceptance decision.
3. How should the 'probably reflection' claim be handled?
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Do not accept it without evidence. Test the reflection hypothesis: change the viewing angle, shade the suspect area, measure reflected apparent temperature with a foil target, compare the lug with identical adjacent conductors at the same load, and verify the load current. If the anomaly disappears when the angle changes or when the area is shaded, reflection is plausible; if it persists, it is a real thermal anomaly. Until that test is done, classify the finding as an unconfirmed anomaly and recommend re-scan or contact measurement. The report must not use 'probably reflection' as a reason to write 'pass'.