Every commercial building in the country spends money on fire protection. Alarms, detectors, sprinklers, extinguishers, exit signage, evacuation plans, annual certification of all of it.
All of that is designed to work after ignition. It limits damage, protects people, and buys time. It is essential and it is legally required.
But it is worth asking the question in the title honestly: if a large share of electrical fires begin with a fault that was detectable for months beforehand, why does so much of the budget sit downstream of ignition?
What actually starts an electrical fire
The mechanism is unglamorous and consistent.
A termination is left slightly under its specified torque, or a component degrades with age and thermal cycling. Resistance at that point rises. The same current now produces heat where it previously produced almost none.
Heat degrades the termination further. Resistance rises again. The curve steepens. Insulation around the connection begins to break down, and eventually something ignites — usually the cable insulation or the plastic of the component itself.
The whole process happens behind a closed cover, in a room nobody enters, over months. Nothing about it is visible or audible. By the time it is either, the surrounding insulation has been cooking for a long time.
We photographed a contactor terminal block after exactly this had run its course. Two of the three terminals held clean copper. The third had burnt back into the housing — carbon, green copper corrosion, scorching through the plastic. The label beside it read tightening torque 4 Nm. A connection a fraction under that spec runs a few degrees warm for months, and warm slowly turns into that.
Why the fault is easy to find and easy to miss
Heat is the symptom, and heat is exactly what an infrared camera measures. A radiometric survey of a switchboard under load will show a developing fault as clearly as a photograph shows a broken window.
Two conditions have to be met, and both are commonly got wrong:
- The board must be live and carrying at least 40% of normal load. A fault only generates heat when current flows through it. Inspect an idle board and a serious defect reads perfectly normal.
- The measurement must be compared, not absolute. A connection at 60 °C means nothing until you know what the other two phases are doing. If they are at 55 °C, that is load heating. If they are at 25 °C, it is a Priority 1 finding.
What the inspection involves
Less disruption than most people expect:
- The building keeps running. Nothing is switched off, no tenancy loses power.
- Covers come off and go back on — a licensed electrician does that on most commercial boards, and we arrange it.
- Each board is surveyed under load, anomalies are measured against reference components, and every finding is classified.
- Anything serious is raised with the site contact on the day, not held for the report.
- The written report follows within 24 hours.
The commercial argument
Fire protection is a cost you carry regardless. Fire prevention is a cost that displaces a much larger one.
A main switchboard survey with a full written report is a few hundred dollars, and additional distribution boards on the same visit are a fraction of that again. Set against a burnt board, the unplanned outage while it is replaced, after-hours labour and expedited parts — and, if it goes as far as fire, an insurance conversation about whether the electrical infrastructure was being maintained.
Most commercial insurers have reached the same conclusion and now attach an annual thermographic inspection as a renewal condition. That is not an administrative burden; it is an underwriter telling you where the risk actually sits.
If you want to put your own figures to it rather than take the argument on faith, the cost of late detection calculator prices the same defect at four points on its way to failure using your repair cost, your downtime rate and your hours lost.
The honest caveat
Thermography shortens the odds. It does not eliminate them.
An infrared survey finds faults that are generating heat at the time of inspection. It will not find a connection that fails suddenly through mechanical shock, and it will not find a fault on a board that was lightly loaded on the day. That is why the answer is a programme rather than a single visit, and why ultrasound runs alongside it to catch arcing and tracking that produce sound before they produce heat.
None of which changes the question. Protection deals with the fire. Prevention deals with the reason there was one.