One note of caution when comparing two conductors on the same heavily loaded circuit breaker; when the breakers are stacked horizontally, the heat from the lower conductor/phase moves upward from convection/conduction and the combined heat at the upper conductor will become warmer than the lower.
You will notice in Charley’s scan (which I modified) there is a V pattern above the lower phase, widening as it approaches the upper phase. The temperature gradients of purple are wider above the hot breaker then they are below the hot breaker. This is the visible effect of convection.
You’ll also notice heat moving across to the next breaker above where there is a slight blue pattern on that breaker which is 5° warmer than other parts of that breaker.
Extremely hot wires also radiate a considerable amount and you will notice a pattern change on adjacent wires and components from this radiating effect.
You can see a slightly lighter purple color on the conductors above the hot breaker on the bottom of the wires. In this case it is a combination of both radiation and convection. In some instances the same pattern will be noted at great distances across the panel, beyond the distance which convection will cause this affect. This would be almost total radiation affect.
We must always consider conditions which may push the anomaly over the top into the “repair immediately” zone when actually it may not have gotten there yet.
[size=2]This becomes even of greater concern when you own a higher end camera as the camera is sensitive enough to pick up these increases and record them.
There’s a high probability you would not even see any of this with an I5.