Step-by-Step: NFPA 70E Safety + NFPA 70B Thermography Workflow
A practical, repeatable workflow for common electrical thermography tasks—built around NFPA 70E electrical safety work practices, NFPA 70B thermography requirements and guidance, and ANSI/NETA MTS ΔT suggested-action criteria. CTE™ colors are used only as a teaching and visual mapping aid after the correct comparison method is established.
🔥 How NFPA 70E, NFPA 70B, and NETA Fit Together
⚡ The Step-by-Step Workflow (70E + 70B Aligned)
Define the task and the access method before the inspection
Define the thermography scope and identify what access is required to obtain a valid line of sight. Keep corrective work—torquing, re-landing conductors, or other repair activity—separate from the thermographic inspection unless it is covered by a separately planned work task.
Opening or removing covers can change electrical exposure. The risk assessment—not a simple door-open/door-closed rule—determines the controls, boundaries, and PPE required for the actual task and equipment condition.
Gather equipment details, safety information, and load context
Collect equipment ID/location, voltage class, equipment type, applicable electrical-safety information, and the load condition. For thermographic comparison, normal operating load is preferred. Where normal loading is not feasible, NFPA 70B annex guidance discusses not less than 40% of nominal circuit loading; record the actual conditions and any limitation they create.
Load and operating conditions matter because heating is load-dependent. Comparable conditions improve the value of later trending, but trending does not replace the required ΔT comparison method for classifying the current finding.
Apply the NFPA 70E risk assessment and job-planning process
Use the employer’s electrical safety program to address shock and arc-flash hazards for the actual task. Establish who may be exposed, the required boundaries and controls, and whether an IR window/viewpoint or another lower-exposure access method can provide the needed line of sight.
A task plan or checklist that ties the actual access method and exposure to the applicable electrical-safety controls and PPE-selection method.
Select protection correctly—based on the work condition, not guesses
Use the employer’s NFPA 70E process for arc-flash PPE selection—incident-energy analysis or the permitted arc-flash PPE category method, as applicable. When exposed energized conductors or circuit parts create a shock hazard, apply the required approach boundaries and shock-protection measures.
Prefer valid line of sight with the least exposure. IR windows/viewports can avoid cover removal. If covers must be opened or removed, reassess the actual exposure and task. Do not assign PPE simply from the equipment name or from a door position.
Set boundaries and control the area (70E discipline)
Establish the arc-flash boundary and other protective measures from the applicable NFPA 70E risk-assessment/PPE method. Where a shock hazard exists, apply the applicable approach boundaries and restrict access as required. Use barricades and signage when required by the electrical safety program.
Keep people who are not required for the task outside the applicable boundaries. Opening a hinged door or cover specifically to expose bare energized conductors or circuit parts is treated differently from noncontact thermography performed without opening doors or covers.
Execute the scan using a repeatable CTE scan path
Scan systematically: mains, feeders, neutrals, grounds, splices, large terminations, and heat-producing components (drives/transformers). Capture thermal + visual pairs. Document the conditions needed to support the measurement, including load context, distance/angle, ambient conditions, emissivity assumptions, and measurement limitations.
Establish a valid reference before assigning a ΔT action tier. Prefer like-for-like comparison of similar components under comparable loading when available; use component-to-ambient comparison when that is the applicable method. Thermal patterns can suggest possible contributors, but thermography alone does not prove the root cause.
Apply the correct ΔT comparison and map it to the ANSI/NETA MTS suggested action
Calculate ΔT from a valid reference and apply the applicable ANSI/NETA MTS suggested-action tier. CTE™ colors are only a teaching/visual mapping of that result; they are not an independent standard and they do not replace the NETA action language. Document possible contributors separately from the measured classification, and perform corrective work in an electrically safe work condition whenever required by the electrical safety program.
Similar components under similar loading: 1–3°C = possible deficiency; warrants investigation (CTE Green). 4–15°C = probable deficiency; repair as time permits (CTE Yellow). >15°C = major discrepancy; repair immediately (CTE Red). There is no Orange tier for this comparison.
Component to ambient: 1–10°C = Green / possible deficiency; warrants investigation. 11–20°C = Yellow / probable deficiency; repair as time permits. 21–40°C = Orange / monitor until corrective measures can be accomplished. >40°C = Red / major discrepancy; repair immediately.
Celsius controls. Fahrenheit may be shown only as a converted ΔT convenience. History, manufacturer limits, load, environment, asset criticality, and other evidence can influence the professional recommendation, but they do not independently recolor or re-tier the measured NETA comparison result.
Close the loop: corrective action + verification scan + trending update
Where the maintenance program calls for verification, rescan after corrective work under comparable operating conditions. Update the finding record and trend history so the repair result can be compared meaningfully with the original condition.
“Before and after” images under comparable conditions are valuable evidence of the maintenance result, but the post-repair scan should be interpreted with the same comparison discipline used for the original finding.
🛡️ Protection Selection (The Correct Way)
🏭 Common Thermography Tasks (Targets + Best Method)
Task 1: 120/240V & 208Y/120V Panelboards
Task 2: 480V Distribution Panels / Switchboards
Task 3: Motor Control Centers (MCCs)
Task 4: Low-Voltage Switchgear
Task 5: Medium-Voltage Metal-Clad Switchgear (as authorized)
Task 6: VFDs / Drives / UPS Systems
📈 CTE™ Reporting Output: Document the Finding So It Can Be Defended
🚀 Become a Certified Thermal Electrician™
If you want thermography that is safer, more defensible, and aligned with NFPA 70E electrical safety practices, NFPA 70B maintenance requirements, and ANSI/NETA MTS ΔT suggested-action criteria, get trained at ThermalElectrician.com.
Educational note: This content is provided for informational and training purposes. Always follow the applicable edition of NFPA 70E, NFPA 70B, ANSI/NETA MTS, the employer/facility electrical safety program, equipment instructions and labeling, and site procedures. Ensure tasks are performed by persons qualified for the work using the controls and PPE required by the actual risk assessment.
