In a busy manufacturing facility in the Southeast, a routine infrared thermography scan picked up an anomaly in a 480V motor control center. Nothing had tripped. No alarms had triggered. Production was running normally. But the thermal image showed a temperature differential of 47°C above ambient on a bus connection — the signature of a failing connection under load. Six weeks later, that facility avoided what engineers estimated would have been a 72-hour unplanned shutdown.
This is what infrared thermography actually does — and why it belongs in every serious electrical maintenance program.
What Is Infrared Thermography for Electrical Systems?
Infrared thermography (also called thermal imaging) is a non-destructive testing method that uses infrared cameras to detect heat signatures in electrical components. All electrical connections, contacts, and conductors generate heat when current flows through them. When a connection is loose, oxidised, or overloaded, resistance increases — and that increased resistance produces abnormal heat that appears in the thermal scan before any visible sign of failure appears.
A trained thermographer analyzes the temperature differentials between similar components operating under the same load conditions. Anomalies are classified by severity — from routine monitoring items to critical faults requiring immediate action.
What Common Faults Does It Detect?
- Loose or oxidised electrical connections in panels, switchgear, and MCC units
- Overloaded conductors and bus bars
- Unbalanced three-phase loading on transformers and panels
- Failing breakers with abnormal resistance
- Overheating motor windings and bearing conditions
- Deteriorating insulation on cables and conductors
Why it Pays to Scan Under Load?
Infrared thermography must be conducted while equipment is operating under a representative load — ideally at least 40% of rated capacity. A cold scan of de-energised equipment reveals nothing. The thermal signature of a failing component only appears when current is flowing and the resistance differential is producing heat. This is why thermography is inherently a live-work activity and must be conducted by qualified individuals following NFPA 70E safe work practices.
How Thermography Integrates With Your Maintenance Program?
NFPA 70B recommends infrared thermography as a core component of a comprehensive electrical maintenance program, with scan intervals typically ranging from annual to quarterly depending on equipment criticality and age. Findings from each scan feed directly into your corrective maintenance queue — from routine re-torquing of connections to urgent panel replacement.
Bowtie Engineering’s NETA-qualified technicians conduct thermography scans as part of our broader electrical maintenance services, providing detailed reports with thermal images, temperature readings, severity classifications, and recommended corrective actions. Explore Bowtie’s Electrical Maintenance and Thermography services or contact us to schedule a thermal scan for your facility.
Frequently Asked Questions
What does infrared thermography detect in electrical systems?
Infrared thermography detects abnormal heat signatures caused by increased resistance in electrical components. Common faults it identifies include loose or oxidised connections in panels, switchgear, and motor control centres, overloaded conductors and bus bars, unbalanced three-phase loading, failing circuit breakers, overheating motor windings, and deteriorating cable insulation — all before any visible sign of failure or triggered alarm appears.
Why does infrared thermography need to be performed while equipment is energised and under load?
The thermal signature of a failing component only appears when current is flowing and resistance differentials are actively generating heat. Equipment must be operating at ideally 40% or more of rated capacity for anomalies to be visible in a thermal scan. A scan of de-energised equipment reveals nothing useful, which is why thermography is inherently a live-work activity conducted under NFPA 70E safe work practices by qualified personnel.
How are thermography findings classified?
Thermography anomalies are classified by severity based on the temperature differential observed above ambient conditions on similar components operating under the same load. Classifications range from routine monitoring items — tracked and re-scanned at the next interval — through to critical faults requiring immediate corrective action before the equipment is returned to service.
How often should infrared thermography scans be performed?
NFPA 70B recommends thermography as a core component of a compliant electrical maintenance program, with scan intervals typically ranging from annual to quarterly depending on equipment criticality, age, and operating environment. High-criticality equipment in continuous production environments generally warrants more frequent scanning than lower-criticality distribution equipment.
How does thermography integrate with the rest of an electrical maintenance program?
Thermography findings feed directly into the corrective maintenance queue. Depending on severity, findings may generate routine work orders for connection re-torquing, scheduled component replacements, or urgent interventions before the next production cycle. When trended across multiple scan cycles, thermography data also enables condition-based maintenance — allowing deteriorating components to be tracked and replaced during planned outages rather than after unplanned failures.