Bad electrical connections get hot before they fail, and a thermal camera sees that heat from a safe distance without touching anything. A loose terminal has resistance; resistance under load produces heat. That heat is visible on an infrared image long before the joint burns, chars its insulation, or causes a fire.
What thermal imaging finds
- Loose terminals — the single most common finding in any distribution board survey.
- Overloaded circuits — a breaker or cable running hotter than its neighbours under similar load.
- Phase imbalance — one phase visibly warmer than the other two.
- Failing components — contactors, capacitors and motor windings heat up before failure.
- Insulation gaps — useful in buildings, and relevant to air-conditioning load in Egyptian summers.
Comparison is the technique
The skill is not reading absolute temperature. It is comparison.
Three identical breakers carrying similar load should sit at similar temperatures. One noticeably warmer is the finding — regardless of what the actual number is. This is why surveys are done under load: an unloaded board tells you nothing at all.
The emissivity trap
This is where most beginners get wrong readings. Thermal cameras measure emitted infrared, and different materials emit differently at the same temperature.
Shiny metal — bare copper busbar, polished terminals — has very low emissivity. It reflects surrounding infrared rather than emitting its own, so it reads far cooler than it actually is. A dangerously hot busbar can appear cold.
The practical fix is to apply a strip of matte electrical tape to the surface, let it reach the same temperature, and measure the tape. Painted and plastic surfaces read reliably without this.
Resolution, and what it really costs you
Detector resolution determines how small a fault you can resolve at a given distance. Low-resolution cameras are perfectly usable close up on a board; they struggle on overhead lines or distant equipment where each pixel covers a large area.
For distribution board work at arm's length, an entry-level resolution is genuinely sufficient. Buying resolution matters when you cannot get close to the subject.
Working safely
The great advantage is distance. A survey is performed with covers closed wherever possible, from outside the arc-flash boundary, without probes touching live parts. Where covers must be removed, that is electrician's work with the appropriate protective equipment — the camera does not change the risk of an open live board.
See Thermal Imaging & Sensing and Testing & Measurement Instruments.
Frequently asked questions
Can a phone thermal attachment do this?
For rough triage, yes. For documented inspection work, dedicated cameras give better resolution and reporting.
Why does bare copper look cold?
Low emissivity — it reflects rather than emits. Measure a matte tape strip applied to the surface instead.
Does the board need to be under load?
Yes. An unloaded circuit produces no heat and hides every fault you are looking for.