Estimated reading time: ~8–10 minutes
Point a thermal camera at something, pull the trigger, and you have a thermogram.
But do you have a reliable inspection result?
Not necessarily.
A thermal camera detects and displays infrared radiation. The thermographer still has to understand what is being observed, how the image was obtained, what may be influencing it, and what the thermal pattern actually means.
Professional thermography therefore requires more than finding the hottest spot.
Here are 11 practices that improve an infrared inspection—and 11 that can undermine one.
11 Best Practices for Infrared Inspections
1. Get closer when you can — but never compromise safety
A useful rule in thermography is “Near is clear.”
The closer you are to the target, the more detail the infrared detector can capture. This becomes especially important when inspecting small components such as electrical terminals, connectors and fuses.
But safety always comes first. Never move closer simply to obtain a better image if doing so puts you inside an unsafe working distance or exposes you to electrical, mechanical or other hazards.
Better image quality is never worth compromising safety.
The priority is:
Safety → Position → Image quality → Measurement
2. Use the best viewing angle available
Whenever possible, aim the camera as close to perpendicular to the target surface as practical.
As the viewing angle becomes steeper, the camera receives less useful radiation from the surface. This can reduce the reliability of the temperature reading and make the thermal pattern harder to interpret.
A better viewing angle helps the camera capture a stronger and more representative infrared signal from the target.
In simple terms:
The more directly you view the surface, the more reliable the thermal information is likely to be.
Avoid very shallow or extreme angles unless the inspection situation requires it.
3. Make sure the thermal image is properly focused
A blurry thermal image is more than just unattractive—it can affect the accuracy of temperature measurements.
Always check that the thermal image itself is in focus before capturing it. Some cameras combine a visible-light image with the thermal image, which can sometimes make the screen appear sharper than the infrared data really is.
Focus is one of the things that cannot truly be corrected later in reporting software.
4. Choose a colour palette that helps you see the problem
Different colour palettes can make different thermal patterns easier to recognise.
High-contrast palettes can help highlight small temperature differences, while simpler palettes such as grey, iron or two-tone displays may make certain patterns easier to understand.
There is no single “best” palette for every inspection.
The goal is not to create the most colourful image—it is to make the thermal pattern clear and easy to interpret.
5. Make sure the target is large enough to measure
The small crosshair shown on the camera screen is not the same thing as the camera’s actual measurement area.
A thermal camera needs enough detector pixels covering the target before it can give a reliable temperature measurement.
If the target is too small or too far away, the camera may also measure some of the surrounding area, which can affect the reading.
This is why thermographers consider concepts such as spot size, spatial resolution and IFOV.
In simple terms:
The measurement area should fit comfortably inside the target.
Distance and target size are fundamental considerations in accurate infrared temperature measurement.
6. Inspect equipment while it is actually working
Many faults only produce a noticeable thermal pattern when equipment is operating.
For example, an electrical connection carrying almost no current may look completely normal—even if a problem exists.
Where possible, inspections should therefore be conducted under normal or representative operating conditions.
The same applies to motors, bearings, pumps and other machinery.
A thermal image is most useful when the equipment is experiencing the conditions you actually want to evaluate.
No meaningful load can mean no meaningful thermal signature.
7. Know what temperature is acceptable for the component
Finding something hot does not automatically mean you have found a fault.
Some components are designed to operate at relatively high temperatures.
Whenever possible, compare the measured temperature with information such as:
- Manufacturer specifications
- Equipment ratings
- Applicable standards
- Normal operating temperatures
- Historical inspection data
Thermographers may use absolute temperature limits, Delta-T (ΔT) comparisons or other assessment methods depending on the equipment and inspection objective.
The question should not simply be:
“Is it hot?”
It should be:
“Is this temperature or thermal pattern abnormal for this component?”
8. Use 0.95 Emissivity as a Practical Starting Point
For many routine electrical inspections, setting the camera emissivity to 0.95 can be a practical and efficient approach.
The key is to understand which surfaces are actually close to that emissivity. Painted surfaces, plastics, rubber, cable insulation and some tapes are often much more suitable for temperature indication than bare, shiny metal.
So instead of constantly changing the emissivity setting, look for reliable clues:
- Measure on high-emissivity surfaces where possible
- Use insulation, painted surfaces or suitable tape (eg. PVC tape) as a reference
- Be cautious with bare copper, aluminium and other reflective metals
- Move or change angle if a hot area may be a reflection
- Treat temperatures on shiny surfaces as less reliable unless properly compensated
A setting of 0.95 is useful for inspection efficiency, but the thermographer still needs to recognise when the surface being viewed does not behave like a high-emissivity target.
The simple rule is:
Keep the camera at 0.95 for routine scanning, but know where to trust the temperature—and where not to.
9. Challenge reflections
Reflections are one of the easiest things to mistake for a thermal anomaly.
A shiny metal component may appear hot because it is reflecting infrared radiation from:
- The thermographer
- Nearby machinery
- Hot pipes
- Lights
- The sky
- Another heat source
One simple check is to move the camera.
If the apparent hot area moves as your viewing position changes, you may be seeing reflected energy rather than heat coming from the component itself.
This becomes increasingly important with low-emissivity surfaces because they tend to reflect more infrared radiation.
10. Look for thermal patterns — not just the hottest spot
Thermography is much more than finding the highest temperature in the image.
Often, the pattern tells you more than the number.
Look for things such as:
- Electrical line in is hotter than line out
- Heating concentrated around a connection
- Unusual temperature gradients
- Cold areas that shouldn’t be cold
- Changes compared with previous inspections
A thermal anomaly is essentially a thermal pattern that does not match what would normally be expected.
A skilled thermographer asks:
“What should this normally look like?”
Then looks for what is different.
11. Report what you observe before deciding what caused it
A thermal camera may show that something unusual is happening, but it does not always tell you why.
For example, abnormal heating at an electrical connection could be caused by:
- Increased resistance
- Loose connection
- Corrosion
- Poor contact
- Overloading
- Another electrical condition
Rather than immediately writing:
“Loose connection.”
A better infrared finding might be:
“Abnormal heating observed at the connection. Further investigation is recommended to determine the cause.”
The thermal finding can then be supported with electrical measurements, visual inspection, equipment history or other diagnostic methods.
Good thermography is not about jumping to conclusions. It is about observing, interpreting and verifying.
Professional thermography guidance places strong emphasis on critical thinking, assessing thermal signatures in context and making appropriate recommendations rather than relying on the image alone.
11 Worst Practices for Infrared Inspections
Infrared cameras make it easy to see temperature differences—but seeing a hot or cold area is only the beginning. A reliable infrared inspection depends on how the inspection is carried out, how the thermogram is interpreted, and what happens after an anomaly is found.
Here are 11 common practices that can reduce the quality and reliability of an infrared inspection.
1. Scanning without a structured and consistent inspection method
Random scanning makes it easy to miss equipment or inspect the same areas repeatedly.
Changing the inspection route or method each time also makes future results harder to compare. A consistent inspection process helps ensure better coverage and more meaningful trending.
2. Failing to verify what is actually being measured
A hot area on the screen may not always be the component you think it is.
The camera could be seeing:
- Another object behind the target
- Heat from a nearby component
- A reflection
- Part of the background
Always make sure you know exactly what you are looking at before interpreting the temperature.
3. Assuming the hottest spot is always the problem
Infrared inspections are not simply about finding the hottest object.
Problems can also appear as:
- Unexpected cold spots
- Uneven heating
- Differences between similar components
- Unusual thermal patterns
What matters is whether the thermal behaviour is normal or abnormal for that equipment.
4. Ignoring whether the thermal pattern makes sense
A temperature number does not tell the whole story.
Look at the shape, location and distribution of the heat. Ask yourself whether the pattern makes sense based on how the equipment operates and how heat should normally flow through it.
Sometimes the pattern provides a more useful clue than the maximum temperature.
5. Treating thermography as a standalone tool without cross-checking
Infrared can reveal that something unusual is happening, but it may not tell you the exact cause.
Where appropriate, findings should be supported by other information such as:
- Electrical measurements
- Visual inspection
- Equipment history
- Mechanical checks
- Engineering judgement
Thermography is often strongest when used together with other inspection methods.
6. Jumping to conclusions from a single thermogram
One thermal image is only one piece of evidence.
A suspicious area may look different when viewed from another angle, distance or operating condition.
Before deciding what the problem is, gather enough information to support the conclusion.
7. Stopping at the obvious finding without rechecking
Obvious hot spots naturally attract attention—but they may not be the only issue.
Other developing problems may be missed, and suspicious findings may go unconfirmed.
Obvious anomalies should not stop the inspection. Continue looking, and recheck anything that does not make sense.
8. Taking poorly framed or unclear thermal images
A useful thermogram should make it obvious what was inspected and where the anomaly is located.
Avoid images that are:
- Too tightly cropped
- Poorly focused
- Missing surrounding equipment
- Difficult to identify
- Taken without a useful visual reference
Someone reading the report later should be able to understand the image without having been there.
9. Failing to record important inspection conditions
A temperature reading is much more useful when you know the conditions under which it was taken.
Depending on the inspection, useful information can include:
- Equipment load
- Operating condition
- Ambient temperature
- Distance
- Relevant camera settings
Without this information, it can be difficult to repeat or compare the inspection later.
10. Over-relying on temperature values without understanding the context
A higher temperature does not automatically mean a more serious problem.
Temperature must be considered together with factors such as the component type, load, surrounding conditions and expected operating temperature.
A number without context can easily be misleading.
11. Producing vague or non-actionable reports
A report that simply says “Hot spot detected” does not give the reader enough information to act.
A useful report should clearly explain:
- What was observed
- Where it was found
- Why it may be important
- What should be checked or investigated next
The aim is not just to show a colourful thermogram. It is to provide information that helps someone make a better maintenance decision.
The key takeaway
A good infrared inspection is not about pointing a camera at equipment and looking for red or yellow areas.
It is about observing, questioning, comparing, verifying and interpreting what the thermal pattern is telling you.
And sometimes, the biggest mistake is not what the camera sees—but what the person behind the camera assumes.