Introduction

Electrical failures rarely happen without warning. In most cases, excessive heat is the earliest and most reliable indicator of developing electrical problems such as loose connections, overloaded circuits, or deteriorating components. Unfortunately, these warning signs are invisible to the naked eye.

Infrared Thermography (IRT) enables early detection of abnormal heat patterns in live electrical systems, without physical contact or operational shutdown. By visualising temperature differences, thermography has become a critical tool for predictive maintenance, fire risk mitigation, and electrical safety management across commercial, industrial, and infrastructure facilities.

Today, infrared inspections are widely adopted by facility owners, insurers, and risk engineers as part of condition-based maintenance and loss prevention strategies.

How Infrared Thermography Works

All objects emit infrared radiation as a function of their temperature. Infrared thermography works by detecting this radiation and converting it into a visible thermal image, where different colours or shades represent temperature variations.

During an electrical infrared inspection:

1. Infrared radiation emitted from electrical components is captured by the thermal camera.
2. The camera sensor converts the radiation into electronic signals.
3. These signals are processed into a thermal image showing relative temperature differences.
4. Trained personnel interpret the image to identify abnormal heat signatures.
   
   

Unlike visual inspections, infrared thermography can identify hidden electrical issues such as internal resistance, phase imbalance, or overloaded conductors while the system is operating under normal conditions.

Key Benefits of Infrared Thermography for Electrical Systems

Proactive Detection of Electrical Faults

Thermography identifies developing problems such as loose terminations, corroded contacts, or overloaded circuits before failure occurs, allowing corrective action to be planned, a proactive rather than a reactive approach.

Non-Intrusive and Safe

Electrical infrared inspections are performed without direct contact and typically without shutting down equipment, reducing safety risks and operational disruptions.

Reduced Downtime and Maintenance Costs

By identifying issues early, organisations can avoid unplanned outages, emergency repairs, and collateral damage – significantly lowering total maintenance costs.

Improved Asset Reliability and Lifespan

Excessive heat accelerates insulation degradation and component ageing. Detecting and correcting heat-related issues helps extend the service life of electrical assets.

Compliance, Reporting and Insurance Support

Thermal inspection reports provide documented evidence of asset condition, supporting maintenance records, regulatory compliance, and insurance risk assessments.

Common Electrical Components Inspected Using Infrared Thermography

Infrared thermography is particularly effective on electrical components where heat is a reliable indicator of distress:

• Distribution Boards (DBs) and Electrical Panels
  Busbars, breakers, cable terminations, neutral bars, and earth connections.
• Circuit Breakers and Switchgear
  Incoming and outgoing terminals, contact points, and internal connections under load.
• Transformers
  Bushings, connections, cooling systems, and load-related heating anomalies.
• Motors and Motor Control Centres (MCCs)
  Power connections, contactors, overload relays, and imbalance-related heating.
• Cables and Electrical Connections
  Especially joints, lugs, and terminations prone to loosening or corrosion.
  
  

Abnormal temperature patterns in these components often indicate high resistance, load imbalance, degradation, or improper installation.

Common Questions About Electrical Infrared Thermography

What temperature difference indicates a faulty electrical connection?

A temperature difference (ΔT) of 10°C or more compared to a suitable reference point is generally considered significant and may indicate a developing electrical fault.

Is absolute temperature sufficient to identify defects?

No. Infrared thermography relies on temperature differences, not absolute temperature values. A component’s temperature must always be compared against a similar component under similar operating conditions.

Should temperature comparison be made within the same phase or between phases?

Best practice is to compare:

• Same phase, same component (most reliable)
• Different phases only when load conditions are similar

Why is one phase running hotter a concern?

If one phase is 10-20°C hotter than others under comparable load, it usually indicates high resistance caused by loose connections, oxidation, or deteriorated contacts.

Does electrical load affect thermography results?

Yes. Infrared inspections are most meaningful when equipment is operating at 40-50% or higher of its rated load. Low load conditions may mask developing defects.

How should findings be prioritised?

Typical severity guidance:

• <5°C – Normal condition
• 5-10°C – Monitor
• 10-20°C – Schedule corrective action
• >20°C – Urgent attention required

 
Why Certified Personnel Matter

While infrared thermography is a powerful diagnostic tool, accurate interpretation requires training and experience. Factors such as emissivity, reflective surfaces, load variability, and environmental conditions can influence results.

Engaging certified thermography professionals ensures:

• Correct inspection methodology
• Reliable interpretation of thermal anomalies
• Actionable, defensible reporting aligned with industry standards
  

A professionally executed infrared thermography program improves safety, reduces fire risk, enhances equipment reliability, and supports informed maintenance decisions.

Take the Next Step

If your facility relies on electrical systems for safe and uninterrupted operation, infrared thermography should be part of your maintenance and risk management strategy.

Contact our certified thermography team to discuss how an electrical infrared inspection programme can be tailored to your assets, operating conditions, and risk profile.

References

• • Fluke Corporation – Thermal Imaging for Electrical Systems
  • Carelabz – Why Electrical Infrared Thermography Inspection Is Important
  • NFPA 70B – Recommended Practice for Electrical Equipment Maintenance
  • NETA ATS / MTS – Acceptance and Maintenance Testing Specifications
  • ISO 18434-1 – Condition Monitoring and Diagnostics of Machines