Electrical Thermography: What It Is and How It Works
Electrical thermography, often called electrical thermal imaging or simply electrical IR scanning, is the process of using an infrared (IR) camera to visualize and measure the surface temperature of electrical equipment. Because most electrical problems start as heat, thermography allows an electrician to detect abnormal temperature patterns long before a failure, fire, or outage occurs.
Unlike a standard visual inspection, electrical thermography “sees” infrared radiation—the heat emitted by conductors, terminations, breakers, busbars, motors, transformers, and other electrical components. This makes it one of the most powerful tools for predictive maintenance, troubleshooting, and safety verification in modern electrical systems.
1. The Physics Behind Electrical Thermography
All objects above absolute zero (−273.15 °C) emit infrared radiation. The hotter an object is, the more IR energy it emits. An electrical thermography camera doesn’t measure temperature directly; it measures this emitted radiation and then uses algorithms and calibration curves to convert that information into a temperature value.
1.1 Infrared Radiation and the Electromagnetic Spectrum
Infrared energy is part of the electromagnetic spectrum, typically between wavelengths of 0.7 µm and 14 µm. Electrical thermography cameras commonly operate in the long-wave infrared (LWIR) region (around 8–14 µm), where building materials and electrical surfaces emit IR energy efficiently.
When you aim an IR camera at electrical equipment:
- The components emit infrared radiation relative to their temperature.
- The IR detector senses this energy.
- The camera converts it into a temperature map.
- The display shows a thermal image revealing temperature differences.
1.2 Emissivity and Why It Matters
Emissivity measures how effectively a material emits infrared energy. Electrical components made from shiny metals (like copper or aluminum) have low emissivity and produce reflections that can distort readings. A trained thermographer knows how to:
- Adjust the camera’s emissivity settings
- Change angles to avoid reflections
- Apply high-emissivity markers for accurate surface readings
2. How Electrical Thermography Cameras Work
An IR camera consists of several key components:
- Infrared lens – Focuses IR energy into the detector.
- Detector array – Converts IR energy into electrical signals.
- Signal processor – Digitizes and interprets sensor output.
- Calibration algorithms – Convert IR readings into temperature values.
- Display – Shows the thermal image and measurement tools.
2.1 Resolution and Detail
Higher resolution (e.g., 256×192, 384×288, etc.) provides more temperature data per image, increasing accuracy and enabling inspection of small electrical components like lugs, terminals, or PCB traces.
2.2 Temperature Range and Sensitivity
Electrical thermography requires cameras capable of detecting small temperature differences, often as low as 0.04°C. This sensitivity is crucial because a small increase in heat may indicate a dangerous electrical condition.
2.3 Refresh Rate
The refresh rate (Hz) determines how smoothly the thermal image updates. Fast refresh rates make scanning easier, especially when inspecting large amounts of equipment quickly.
3. What Electrical Thermography Actually Measures
Thermography does not measure electricity. It measures the heat effects caused by:
- I²R losses from resistance (loose connections, corrosion, damaged conductors)
- Overloaded circuits
- Unbalanced phases in 3-phase systems
- Harmonics causing neutral or transformer heating
- Cooling system failures
The thermal imager shows a temperature map of the equipment surface. The skill lies in interpreting what those temperatures mean.
4. How an Electrical Thermography Inspection Is Performed
4.1 Pre-Inspection Planning
- Identify equipment to be inspected
- Verify access requirements and safety boundaries
- Ensure equipment is under adequate load (≥40% recommended)
- Review electrical drawings if available
4.2 Scanning Process
- Wear PPE and follow arc-flash safety protocols
- Open panels only when safe to do so
- Scan busbars, stabs, breakers, lugs, neutrals, and terminations
- Capture both thermal and visual reference images
- Adjust emissivity, palettes, and temperature ranges as needed
4.3 Evaluation and Reporting
- Compare components under similar load conditions
- Analyze temperature rise above ambient
- Identify abnormal patterns indicating defects
- Create a detailed inspection report with findings and recommendations
5. Applications of Electrical Thermography
- Switchgear and switchboards
- Panelboards and load centers
- Motor control centers (MCCs)
- Transformers and UPS equipment
- Busway and bus duct systems
- Data centers and critical IT power systems
- Industrial motors, drives, and control cabinets
6. Limitations and Common Errors
- Low load can hide defects
- Reflections from shiny metals can distort temperature readings
- Incorrect emissivity settings reduce accuracy
- Thermography shows surface temperature only, not internal conditions
- Lack of electrical knowledge can lead to misdiagnosis
This is why proper training is essential—thermography is a powerful tool only when interpreted by someone who understands both infrared science and electrical systems.
7. Best Practices for Reliable Electrical Thermography
- Inspect under typical load conditions
- Compare similar components (phase-to-phase analysis)
- Account for ambient conditions and airflow
- Use correct emissivity settings
- Document findings clearly with thermal and visual images
- Trend temperatures over time using periodic inspections
- Follow all NFPA and OSHA electrical safety standards
8. Why Electrical Thermography Is Now a Core Skill for Modern Electricians
Electrical systems today are more complex, more heavily loaded, and more mission-critical than ever before. Thermography allows electricians to:
- Prevent failures and downtime
- Reduce fire risk
- Improve energy efficiency
- Verify workmanship and repairs
- Provide higher-value services to customers
When combined with proper electrical knowledge and training, thermography becomes one of the most effective predictive maintenance tools available.
Become a Certified Thermal Electrician™
Electricians who want to master electrical thermography, interpret thermal images correctly, and perform professional-grade inspections should pursue the Certified Thermal Electrician™ credential.
This program is designed specifically for electricians and covers:
- Infrared science and emissivity
- Electrical failure modes and heat signatures
- NFPA 70B predictive maintenance practices
- Hands-on thermal imaging techniques
- Report writing, documentation, and trending
- Safe scanning procedures for energized equipment
Learn more or enroll at:
https://thermalelectrician.com
