SDG #241 Electrical Cable Tracing with a Thermal Camera

Finding a cable that disappears into a wall, a floor void or a conduit run is one of those jobs where the usual tools fall short. Inductive cable tracers pick up neighbouring conductors, metal detectors flag every nail and pipe, and pulling a fish tape blind risks damaging something expensive. This video takes a different approach: deliberately load the conductor so it dissipates a small amount of power, then use a thermal camera to watch where that heat surfaces.

The method works because even a modest current through a length of copper produces a measurable temperature rise, and that heat conducts outward through plaster, plasterboard or screed until it shows as a faint linear signature on the surface. The key practical points are all about control: enough current to generate a visible delta without cooking the insulation, enough time for the heat to soak through the covering material, and a camera sensitive enough to resolve small differences. Thin coverings and low thermal mass give quick, sharp results. Deeper runs under thick plaster or concrete need longer soak times and a blurrier trace, so patience matters more than raw camera resolution.

For anyone weighing up a thermal camera purchase, this is a genuinely useful argument in favour of one beyond the usual PCB fault finding. Thermal sensitivity, expressed as NETD, matters more here than pixel count, since the temperature differences involved can be well under a degree. The technique also transfers to underfloor heating loops, hidden pipework and identifying which of several similar cables in a bundle is actually carrying load.