Switchboard thermal imaging is a scan of a live, loaded switchboard with an infrared camera. The camera shows heat as colour, so a loose joint, an overloaded cable or a failing breaker shows up as a hot spot long before it trips, melts or starts a fire. It is a fault-finding check, done without switching the board off.
Here is what the scan can and cannot see, when it is worth doing, and how to read the report you get at the end.
What does thermal imaging of a switchboard actually show?
It shows where electrical energy is turning into heat instead of reaching the load. Every connection has some resistance, and resistance under current makes heat. A healthy joint runs only slightly warmer than the cable either side of it. A joint that has loosened or corroded runs much hotter, and on the camera it glows against everything around it.
The most common findings on a commercial board are:
- Loose terminations. Screws on breakers, busbars and neutral links loosen over years of heating and cooling, and the joint gets hotter each cycle.
- Overloaded circuits. A whole cable run warmer than its neighbours means it is carrying more current than it was sized for.
- Phase imbalance. On a three phase board, one phase noticeably hotter than the other two means the load is unevenly spread.
- Worn breakers and contactors. A device that is hot internally while its terminals are fine is usually near the end of its life.
None of these make noise or trip anything early on, which is the point of the scan. A buzzing or warm board is the later stage of the same problems, covered in why is my switchboard buzzing.
Why does the switchboard need to be under load for the scan?
A fault only heats up when current flows through it, so a board scanned at 6am with the building empty can look clean while the same board at 2pm has a joint running hot. The scan is booked for normal trading hours, when lighting, air conditioning, kitchens and plant are all running. Many inspectors work to a rule of thumb of at least 40 percent of the board's rated load, and they record the load at the time so next year's scan can be compared fairly.
That is also why thermal imaging rarely needs an outage. The electrician removes the escutcheon (the cover panel that sits over the breakers) so the camera can see the terminals directly, works under a live work risk assessment, and puts the cover back. The building keeps trading.
What can a thermal scan miss?
Anything the camera cannot see directly, and anything that is not carrying current at the time. Infrared does not pass through glass, most clear plastic covers or a closed metal door, so a scan through the panel window reads the window, not the parts behind it. Cables buried in walls and ceilings are mostly out of view. A circuit that was switched off or lightly used on the day will not show its faults.
It is also a heat check, not a full electrical test. It does not tell you whether a safety switch trips in time, whether insulation is breaking down, or whether the earthing is sound. Those need their own tests. Where the board is fine but the cabling behind it is old, the question becomes the one in does your commercial building need rewiring.
Want your switchboards scanned?
DM Electrical carries out switchboard thermal imaging for commercial buildings, strata and business premises across the Northern Beaches, North Shore, Eastern Suburbs and greater Sydney, with a written report on every board.
How do you read a thermal imaging report?
Each finding should come with an infrared image, a normal photo of the same spot, the measured temperature, the temperature rise compared with a similar component, and a priority. The comparison matters more than the raw number. A breaker at 45 degrees means little on its own, but the same breaker running 20 degrees hotter than the identical breaker next to it on a similar load is a clear fault.
Priority bands differ between inspectors and standards, so read the report's own key. As a general guide, the pattern on the image usually points to the cause:
| What the image shows | Likely cause | Usual fix |
|---|---|---|
| One terminal much hotter than the rest of the device | Loose or corroded connection | Isolate, clean and re-terminate to the correct torque |
| A whole cable warm along its length | Circuit carrying more than its rating | Move load to another circuit or upsize the cable and protection |
| One phase hotter than the other two | Load unevenly spread across phases | Rebalance circuits across the phases |
| Hot spot inside the body of a breaker | Device wearing out internally | Replace the breaker or contactor |
| Neutral link or neutral bar running hot | Loose neutral or heavy harmonic load | Re-terminate and check the neutral sizing |
Most of these repairs are small once found. The ones that need an outage, such as re-terminating a main busbar, get booked after hours. If the scan shows the board itself is at capacity, the conversation moves to a switchboard upgrade.
How often should switchboard thermal imaging be done?
For most commercial buildings, once a year, timed so each scan can be compared with the last. That is the interval most maintenance plans use, and it is the one we build into annual maintenance for commercial electrical clients. Sites where an outage costs more than usual are often scanned more often: buildings with server rooms, cold storage, commercial kitchens or heavy plant. Some insurers ask for a recent scan as part of a property risk survey.
A scan is also worth doing outside the normal cycle after a big change in load, such as a fitout, new air conditioning or EV chargers in the car park, and any time a board feels warm, smells hot or makes noise.
For houses, scheduled scans are uncommon. Thermal imaging at home is usually a diagnostic tool, brought out when there is already a symptom such as a scorched power point, a warm board or a circuit that keeps tripping.
Frequently asked questions
Does switchboard thermal imaging need the power turned off?
No. The scan has to be done with the board live and carrying its normal load, because faults only heat up when current flows through them. The electrician removes the cover panel, scans under a live work risk assessment and refits it. Power is only turned off later if a repair needs it.
Is switchboard thermal imaging a legal requirement in NSW?
There is no blanket rule that every switchboard must be scanned each year. The duty to manage electrical risk in a workplace sits with the business or building owner, and thermal imaging is one of the common ways to show that is being done. Insurers, strata maintenance plans and building owners often set the annual interval.
Can thermal imaging find electrical faults inside walls?
Only sometimes. A very hot cable or connection close to the wall surface can show through plasterboard as a warm patch, but most wiring inside walls and ceilings is out of the camera's view. Thermal imaging is most reliable on equipment it can see directly, such as switchboards, terminals and exposed cable runs.
Who can do a switchboard thermal scan?
The scan itself means opening a live switchboard, so it should be done by a licensed electrician who is trained to use the camera and read the results. Any repair the report calls for is electrical work and needs a licensed electrical contractor.
The bottom line
Switchboard thermal imaging finds the faults that give no warning: loose joints, overloaded circuits and worn breakers that are heating up quietly. Book it during trading hours so the board is under load, do it once a year on commercial boards, and compare each report with the last. Get in touch to book a scan.