TR20 Pro vs TR384C: Choosing Thermal Cameras for Certified Thermal Electricians™

Thermal Imaging for Electricians: More Than Just “Heat Pictures”

A Certified Thermal Electrician™ is not simply pointing a camera at equipment and looking for “red spots.” Professional electrical thermography requires an understanding of the electrical system, operating condition, measurement variables, and the limitations of what a thermal image can actually prove.

A CTE™ professional considers:

• I²R heating principles and how current and resistance contribute to electrical heating without assuming that the thermal pattern alone proves the root cause.
• Appropriate operating and load conditions. Normal operating load is preferred. NFPA 70B annex guidance discusses not less than 40% of nominal circuit loading where normal loading is not feasible, but 40% is not a universal pass/fail threshold for a valid thermographic inspection.
• Valid comparisons between similar electrical components under similar loading or, when applicable, between an electrical component and ambient air temperature.
• Measurement factors including emissivity, reflected apparent temperature, viewing angle, focus, distance, IFOV/MFOV, environmental conditions, and target size.
• The appropriate ANSI/NETA MTS suggested-action criteria after the correct comparison has been established.

The camera matters, but camera specifications do not replace proper measurement technique. A higher-resolution image is useful only when the thermographer understands how to obtain and interpret a valid measurement.

The Mileseey TR20 Pro – A 50 Hz Everyday Thermography Workhorse

The TR20 Pro combines 320 × 240 infrared resolution with a 50 Hz frame rate and a relatively wide 50° × 37.2° field of view. That combination can make it convenient for general electrical inspection, service work, troubleshooting, and routine condition assessment.

Key Characteristics of the TR20 Pro

• Native IR Resolution: 320 × 240.
• Refresh Rate: 50 Hz.
• Field of View: 50° × 37.2°.
• Thermal Sensitivity: ≤40 mK.
• Temperature Range: –20°C to 550°C (–4°F to 1022°F).
• Manufacturer Accuracy Specification: ±2°C or ±2% under specified conditions.
• Visible Camera: Yes.
• Image Modes: Thermal, fusion-related modes, PIP, and visible imaging.
• Measurement Tools: Center, hot-spot, and cold-spot measurement.
• Protection: IP54.
• Battery: Manufacturer lists up to approximately 8 hours of use.

How a Certified Thermal Electrician Might Use the TR20 Pro

1. Electrical Troubleshooting

When a customer reports abnormal equipment behavior, the TR20 Pro can be used as one part of the troubleshooting process.

• Scan accessible electrical components while operating under an appropriate load.
• Compare similar phases or equivalent components when valid comparison conditions exist.
• Identify localized or asymmetric thermal patterns that deserve further investigation.
• Document thermal and visual images for the inspection record.

A hot breaker, lug, conductor, or neutral connection does not by itself prove a loose connection, corrosion, overload, or defective component. The thermal pattern identifies where additional electrical or mechanical investigation may be needed.

2. Routine Panel and Distribution Equipment Inspections

Within an appropriate electrical maintenance program, the TR20 Pro can be used to inspect:

• Main service and distribution equipment.
• Panelboards and subpanels.
• Accessible feeder and branch-circuit terminations.
• Disconnects, contactors, breakers, and similar electrical equipment.
• Motors, HVAC electrical components, and other operating equipment.

The 50 Hz frame rate provides smooth live imaging when moving across equipment. Frame rate, however, does not determine temperature accuracy or the validity of the measurement.

3. Follow-Up Inspection After Corrective Work

The TR20 Pro can also be used for follow-up thermography after appropriate corrective maintenance.

• Return the equipment to an appropriate operating condition.
• Rescan the same target using sufficiently comparable measurement conditions.
• Evaluate whether the previous abnormal thermal pattern remains present.
• Document the post-maintenance condition.

A lower post-repair temperature can support the conclusion that the thermal condition changed, but it does not prove proper torque or establish that every underlying cause has been corrected. Torque and installation requirements must be verified through the appropriate mechanical or electrical procedure.

4. Supporting an Electrical Thermography Service

Contractors can use the TR20 Pro as part of an electrical thermography service by providing:

• Electrical condition-assessment scans.
• Thermal and visual documentation.
• ΔT comparisons where the measurement conditions support quantitative analysis.
• Follow-up scans after corrective maintenance.
• Professional reports documenting findings and limitations.

The Mileseey TR384C – Higher Resolution and Additional Documentation Features

The TR384C uses a 384 × 288 infrared detector, providing 110,592 detector pixels. Its 28° × 21° field of view is also substantially narrower than the TR20 Pro. That combination can place more detector pixels on a smaller target at a given working distance, depending on the inspection geometry.

More detector pixels can be valuable when examining smaller components or working from greater distances, but detector resolution alone does not guarantee an accurate temperature. Target size, focus, MFOV, emissivity, reflections, viewing angle, and environmental conditions still matter.

Key Characteristics of the TR384C

• Native IR Resolution: 384 × 288 — 110,592 detector pixels.
• Refresh Rate: 25 Hz according to the current Mileseey product listing.
• Field of View: 28° × 21°.
• Thermal Sensitivity: ≤40 mK.
• Temperature Range: –20°C to 550°C (–4°F to 1022°F).
• Manufacturer Accuracy Specification: ±2°C or ±2% under specified conditions.
• Laser Distance Measurement: Up to 20 m (66 ft).
• GPS: Included.
• Wi-Fi: Included.
• Visible Camera: 2 megapixels.
• Measurement Tools: Center, hot/cold spot, and multi-area measurement.
• Battery: Manufacturer lists up to approximately 10 hours of use.

How a Certified Thermal Electrician Might Use the TR384C

1. Detailed Electrical Surveys

The higher pixel count and narrower field of view can be useful when inspecting complex electrical equipment containing smaller targets.

• Motor control centers and dense distribution equipment.
• Switchboards and switchgear.
• UPS and data-center electrical distribution systems.
• Bus connections, breakers, conductors, and terminations.
• Motors, VFD systems, and related electrical equipment.

The objective is not merely to produce a sharper picture. The additional spatial detail can help place more detector pixels on the actual component being evaluated, improving the opportunity for a valid quantitative measurement when all other measurement requirements are satisfied.

2. Small Targets and Greater Working Distances

Higher resolution and narrower field of view can help when the thermographer must evaluate smaller components from a safe working position.

The thermographer should still confirm that the target meets the camera's practical measurement-spot requirement. Digital enlargement of an image does not create detector resolution that was not present when the image was captured.

3. Historical Trending and Maintenance Documentation

For facilities performing recurring inspections, the TR384C can support:

• Repeatable radiometric documentation of critical electrical assets.
• Asset and location identification using available GPS and documentation features.
• Historical comparison when operating and measurement conditions are sufficiently comparable.
• Professional reports containing thermal and corresponding visual information.

Trending is supporting evidence. A small change from a previous inspection does not automatically create an ANSI/NETA action tier and does not independently change a CTE™ color. The applicable thermographic comparison still must be established for the current inspection.

4. Building and Energy-Related Applications

The TR384C can also be used for non-electrical thermography applications such as building envelope and energy-related assessments when the user has the appropriate training and follows the applicable inspection methodology.

• Thermal patterns associated with insulation discontinuities.
• Building-envelope temperature differences.
• Potential air-leakage patterns when proper test conditions exist.
• HVAC and mechanical thermal observations.

These applications are separate from the electrical comparison methods taught for CTE™ electrical thermography and should not be evaluated using the ANSI/NETA electrical suggested-action tables.

5. Professional Reports and Presentations

Higher detector resolution can provide additional visual detail in reports, but report quality should never be confused with measurement validity.

A professional thermography report should prioritize:

• Correct equipment and asset identification.
• Radiometric thermal data.
• Corresponding visual/context images.
• Operating and load conditions.
• Target and reference temperatures.
• Calculated ΔT where applicable.
• The correct comparison method.
• Measurement limitations.
• Applicable ANSI/NETA suggested-action criteria when used.
• A technically supported professional recommendation.

TR20 Pro vs TR384C – Side-by-Side Comparison

Why a Certified Thermal Electrician™ Might Consider Owning Both

1. Different Tools for Different Inspection Conditions

The differences in detector resolution, field of view, frame rate, and documentation features can make one camera more convenient than the other for a particular inspection.

• TR20 Pro: useful for general electrical inspection, troubleshooting, service work, and situations where a wide field of view and smooth live image are helpful.
• TR384C: useful when more detector pixels on the target, a narrower field of view, GPS, laser distance measurement, or additional documentation features are desirable.

The correct camera is the one that can adequately resolve the actual target from the available safe working position while meeting the intended measurement objective.

2. Operational Redundancy

Two capable cameras can provide practical redundancy. If one camera is charging, being serviced, or unavailable, the second camera can help prevent interruption of scheduled work.

Redundancy can be valuable for contractors who perform frequent thermographic inspections, but owning multiple cameras is not itself a measure of professional competence.

3. Matching Spatial Resolution to the Target

Not every job requires the same field of view or detector resolution. A large breaker or bus assembly may be easily resolved by either camera, while a small termination at a greater working distance may benefit from the TR384C's higher pixel count and narrower field of view.

Regardless of which camera is used, the thermographer must ensure the target meets the practical measurement-spot requirement for the intended quantitative measurement.

4. Growing an Electrical Thermography Service

Many electricians begin with thermography as an extension of existing electrical work and later expand into formal inspections, recurring maintenance programs, and more detailed reporting.

That growth can include:

• Electrical thermographic surveys.
• Condition-assessment programs.
• Post-maintenance verification scans.
• Historical asset documentation.
• Commercial and industrial maintenance programs.
• Specialized reporting for facility owners and maintenance teams.

Inspections performed as part of an NFPA 70B electrical maintenance program should follow the applicable maintenance requirements and equipment-condition framework rather than being marketed simply as “NFPA 70B-style” camera scans.

The CTE™ Technical Framework Still Comes Before the Camera

Whether the thermographer uses the TR20 Pro, TR384C, or another suitable radiometric thermal camera, the classification process remains the same.

Similar Components Under Similar Loading

• 1–3°C ΔT: Possible deficiency — warrants investigation.
• 4–15°C ΔT: Probable deficiency — repair as time permits.
• Greater than 15°C ΔT: Major discrepancy — repair immediately.

In the CTE™ visual teaching system these map to Green, Yellow, and Red. There is no Orange tier for the similar-component comparison.

Component-to-Ambient

• 1–10°C ΔT: Possible deficiency — warrants investigation.
• 11–20°C ΔT: Probable deficiency — repair as time permits.
• 21–40°C ΔT: Monitor until corrective measures can be accomplished.
• Greater than 40°C ΔT: Major discrepancy — repair immediately.

In the CTE™ visual teaching system these map to Green, Yellow, Orange, and Red.

Final Thoughts

The Mileseey TR20 Pro and Mileseey TR384C offer two different combinations of detector resolution, field of view, frame rate, and documentation features that can be useful to electrical thermographers.

• The TR20 Pro provides 320 × 240 resolution, a wide field of view, and smooth 50 Hz live imaging that can work well for everyday electrical inspection.
• The TR384C provides 384 × 288 resolution, a narrower field of view, GPS, laser distance measurement, Wi-Fi, and additional measurement tools that can be useful for detailed survey and documentation work.

A Certified Thermal Electrician™ does not need to own both cameras to perform professional electrical thermography. For contractors who perform enough thermography to benefit from different optical characteristics, additional documentation features, or backup equipment, owning both can be a practical business choice.

The most important investment remains the thermographer's ability to understand measurement physics, electrical systems, loading, comparison methodology, electrical safety, documentation, and the limitations of what the thermal image can prove.

Educational note: Always follow the thermal-camera manufacturer's current instructions and specifications, the employer or facility electrical safety program, applicable NFPA 70E electrical safety-related work practices, the applicable NFPA 70B electrical maintenance requirements, ANSI/NETA criteria when used by the maintenance program, equipment manufacturer instructions, equipment ratings, and site-specific procedures. CTE™ certification does not by itself establish task-specific qualification under NFPA 70E.