The principle: faults are hot before they are failures
Electrical resistance produces heat. A connection that has worked loose, a corroded joint, an unbalanced or overloaded phase — each dissipates more heat than its healthy neighbours, often long before anything trips, smokes or burns. An infrared camera sees that temperature difference directly, through the running installation, without a shutdown and without touching a conductor.
That is the entire case for thermography: it is one of the few inspections that finds electrical faults before they become downtime or a fire investigation.
Why “under normal load” matters
A panel scanned during a shutdown, or at 3 a.m. when the building is empty, shows nothing — no load, no current, no heat signature. A meaningful survey is scheduled when the installation carries its representative working load, and the report should state the load conditions at the time of scanning. If a vendor offers to scan your panels during a holiday shutdown, the report will be pretty and useless.
What the survey covers
Typical scope for a corporate facility:
- Main LT panels, busbars and bus couplers
- Distribution boards and feeder connections
- Motor starters, drives and heavy single loads
- UPS, battery and DG changeover connections
- Anything an insurer or previous audit specifically flagged
Reading the hotspot report
A usable report does not just show thermal images. Each finding carries the measured temperature, the reference temperature of a comparable healthy phase, and a severity ranking — typically from “monitor at next survey” up to “rectify immediately”. Severity is judged on the temperature rise over reference and the criticality of the circuit, not the absolute number alone.
The report’s job is to let your electrical team fix the worst items first, and to let a re-scan prove the fix worked. A survey without a repeat scan after rectification is a diagnosis without a discharge summary.
Who asks for it, and how often
Insurers increasingly make an annual thermography report a condition of fire-risk cover for commercial and industrial buildings; electrical safety audits and corporate EHS programs ask for the same. Annual scanning is the working norm, with six-monthly cycles for heavily loaded or continuously running installations. The certificate-and-report file, dated and load-stated, is what the auditor accepts — which is why thermography is usually run as a calendar service alongside meter calibration rather than as a one-off.