Thermography and NFPA 70B 2023: What You Need to Know for Electrical Preventive Maintenance
- FLaiTek
- Sep 17
- 3 min read
Updated: Oct 14
Thermography has become one of the most effective ways to evaluate the health of electrical systems. By using a thermal camera or infrared camera, technicians can detect and measure invisible infrared radiation emitted by energized equipment. This process helps identify early warning signs such as overheating, loose terminations, insulation breakdown, or other defects that, if ignored, could result in costly failures, equipment damage, or even fires and safety hazards.
However, infrared inspections are far more than simply capturing images of “hot spots.” To be effective, they require structured procedures, standardized documentation, and accurate reporting. This is where NFPA 70B: Recommended Practice for Electrical Equipment Maintenance plays a vital role.
Updates in the thermography and NFPA 70B 2023
The NFPA 70B 2023 edition introduced important updates that impact how thermography should be integrated into an electrical preventive maintenance (EPM) program. These revisions emphasize consistent reporting, proper interpretation of data, and actionable recommendations for improving system safety and reliability.
Focus on Delta T (ΔT)
One of the central updates is the requirement to measure and document temperature differences (Delta T or ΔT). Section 7.4.1 states that inspections should compare the temperature difference between similar components under similar loads, as well as between a component and the surrounding ambient air.
ΔT is a critical diagnostic value—it can highlight abnormal heating caused by issues such as excessive resistance, harmonic distortion, overloading, or component deterioration. Identifying and tracking these differences makes it easier to prioritize corrective actions before equipment failure occurs.
Reporting Requirements
Section 7.4.3 further reinforces that temperature deviations between the target area and a reference area must be documented. In practice, this means every identified anomaly must include both thermal and visual images, measured ΔT values, and details about operating conditions.
To comply with NFPA 70B and industry best practices, inspection reports should include:
Date and time of inspection
Thermographer’s name and qualification
Type and model of the thermal imaging equipment used
Emissivity and reflected temperature settings
Ambient temperature and humidity levels
Electrical load and operating conditions during the scan
Location and ID of inspected equipment
Thermal and visible images for each finding
ΔT values for areas of concern
Recommended action steps and severity ratings
Clear and standardized reporting ensures consistency across inspections. Retaining this data allows teams to track condition changes over time and evaluate the effectiveness of maintenance programs. Annex E of NFPA 70B provides sample report formats to support compliance.
Inspection Frequency Based on Equipment Condition
Another significant update in NFPA 70B 2023 is guidance on how often thermal inspections should be conducted, depending on the physical condition of the equipment. The standard outlines four categories:
Condition 1 (Like New): Inspections at least once every 12 months. Applies when the enclosure is clean, free of moisture, and no issues have been flagged by monitoring systems.
Condition 2 (Satisfactory): Also requires inspection at least annually, but applies when prior maintenance has revealed issues, deviations from baseline data exist, or predictive systems have raised alerts.
Condition 3 (Degraded): Requires inspection at least once every 6 months. This level applies when significant maintenance issues have been identified in consecutive cycles, or when urgent alerts from monitoring systems are active.
Condition 4 (Non-Serviceable): Requires immediate action. Equipment at this level poses imminent safety risks and must be removed from service in accordance with Section 8.7.1.3.
By applying these inspection intervals, facility managers can allocate resources more effectively while ensuring that high-risk equipment receives the attention it needs.
Why These Updates Matter
For facility owners, safety managers, and maintenance teams, the NFPA 70B 2023 updates make thermography more actionable. Instead of simply identifying heat patterns, inspections now provide structured data that supports risk assessment, predictive maintenance, and long-term reliability strategies.
At FLaiTek, our advanced thermal cameras and infrared cameras are designed to meet these evolving standards. With high sensitivity, accurate measurement, and robust reporting features, our solutions empower electrical professionals to perform inspections that are compliant, precise, and effective.
Thermography is not just a diagnostic tool—it is an integral part of modern preventive maintenance. By following the NFPA 70B 2023 guidelines on ΔT measurement, documentation, and inspection frequency, organizations can enhance equipment reliability, reduce downtime, and improve workplace safety.
With the right thermal imaging technology and standardized reporting practices, electrical inspections evolve from snapshots of problems to a long-term strategy for risk reduction and operational excellence.
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