What Is Thermal Imaging?
Learn how thermal imaging works and what infrared inspections can reveal
Understanding Thermal Imaging
Thermal imaging, also known as infrared thermography, is a non-contact inspection method used to measure and visualise surface temperature differences.
A thermal camera detects infrared energy coming from object surfaces within its field of view and converts it into a visible image called a thermogram. Different colours represent different temperatures, making warmer and cooler areas easier to compare.
These temperature patterns can reveal issues that may not be visible during a routine inspection, such as an overheating electrical connection, a bearing operating warmer than comparable equipment, or a cooler surface pattern associated with moisture.
Thermal imaging is used across electrical systems, mechanical equipment, and buildings because it allows large areas and multiple components to be assessed quickly with minimal disruption.
How Does a Thermal Camera Work?
Everything around us emits infrared energy. Unlike a standard camera, which records visible light, a thermal camera detects infrared radiation using a specialised detector designed for accurate non-contact temperature measurement.
Infrared energy passes through the camera lens to the detector, where it is processed into an image showing the apparent temperature distribution across the inspected surface. Each pixel represents a temperature measurement, allowing comparison between nearby areas.
The displayed colours are not the actual colours of the object. Depending on the selected palette and temperature range, warmer areas may appear white, yellow, orange, or red, while cooler areas may appear purple, blue, or black.
Thermal imaging is particularly useful for comparison. An isolated hotspot, uneven temperature pattern, or difference between similar components may indicate an area requiring closer investigation under comparable operating and environmental conditions.
Measurements can be affected by surface material, emissivity, reflections, viewing angle, distance, weather, airflow, equipment load, and camera settings. Shiny metals are especially reflective and may return infrared energy from surrounding objects, creating patterns that can resemble genuine hotspots or misleading temperature differences.
What Can Thermal Imaging Identify?
Thermal imaging can support the investigation of electrical, mechanical, moisture, and insulation-related issues. It is most effective when the condition produces a measurable temperature difference at an accessible surface.
Electrical Overheating
Electrical thermal imaging can identify abnormal heating associated with loose or deteriorated connections, overloaded equipment, phase imbalance, failing components, and poor cable terminations.
Electrical equipment should normally be inspected while operating under meaningful load. A fault may not produce a noticeable temperature difference when very little current is flowing.
Mechanical Issues
Mechanical thermal imaging can help identify abnormal heating across motors, bearings, pumps, gearboxes, conveyors, and other rotating equipment.
Changes in friction, lubrication, alignment, load, or cooling may produce temperature patterns that differ from similar components or previous inspections.
Moisture-Related Patterns
Thermal imaging does not detect water directly. It identifies surface temperature patterns that may be consistent with moisture-affected materials.
These patterns may help narrow down areas affected by roof leaks, plumbing leaks, water tracking, damaged insulation, or other moisture ingress. Further verification with a moisture meter or targeted investigation may still be required.
Insulation Defects
Missing, displaced, compressed, or wet insulation can produce uneven surface temperatures. Under suitable conditions, thermal imaging may help identify insulation gaps, thermal bridging, air leakage, and uneven performance across walls, ceilings, and insulated panels.
Thermal Imaging Limitations and Interpretation
A thermal camera does not provide X-ray vision and generally cannot see through walls, ceilings, switchboard covers, machinery guards, or other solid materials. It measures infrared energy from the visible surface.
A concealed issue may still alter the visible surface temperature and create a detectable pattern, but the camera is not seeing through the material. Thermal imaging cannot confirm moisture on its own, reveal every electrical or mechanical fault, inspect components hidden behind covers, pinpoint every leak source, or replace other testing where required.
Some faults do not produce heat, occur only intermittently, or are too deeply concealed to affect the visible surface.
Capturing a thermal image is relatively straightforward, but interpreting it correctly requires experience. A warm or bright area is not automatically a fault. Normal loading, reflections, sunlight, airflow, surface materials, and nearby heat sources can all create unusual patterns.
An experienced thermographer considers the equipment type, operating load, emissivity, reflections, environmental conditions, comparable components, visual observations, and site history before determining whether a pattern is significant.
Thermal imaging is best described as a non-contact and minimally disruptive diagnostic tool. It can identify areas requiring further investigation, but it does not replace other inspection or testing methods where these are needed.
Thermal Imaging Services in Auckland
Auckland Thermography provides professional thermal imaging inspections for electrical systems, mechanical equipment, moisture concerns, and building diagnostics throughout Auckland.
Auckland Thermography Ltd
021 139 2360
22/18 Hewlett Rd, Massey, Auckland 0614
Hours & locations
Monday - Friday: 6am - 5pm
Auckland based - inspections can be carried out NZ wide and overseas by request
