You can’t say its bad without other information, you are correct.
However, at some point HI’s my be going beyond there limits.
They must be careful, but recommending further evaluation is in order here. Studying the thermal patterns of the scan provide a lot of information as to what is going on if you are trained to recognize them. This is sufficient for further investigation.
However, real-life scenarios out there will often result in a verbal conflict between electricians and home inspectors using thermal imaging. So, I caution this approach. I recommend the inspector be further trained and purchased the appropriate equipment so that you can conclusively report the defect as being significant.
When we elect to go beyond our scope by using thermal imaging, we cannot be falling back on the home inspection SOP. We must formulate our own SOP which is safe to the inspector and provides enough information to work with.
Nobody has answered my question yet, but this is a two pole 240 V breaker. Gas furnaces do not run on 240 V in residential applications!
We must consider whether this is a direct or indirect reading, as Jim is pointing out, the source of heat is out of view and likely an indirect measurement regardless of whether it is a defective breaker or blindside connection. Very low temperature rises can be significant when they are indirect readings.
The amount of electrical current flowing through the circuit is vital information needed to determine at what capacity the breaker is loaded. The circuit should be loaded to a least 30% capacity for scanning. If we have 140°F breaker under a 5% load there is a serious issue there. What’s going to happen at 90%? A fire?
As for the hot furnace, the other information needed is consideration of the static air pressures of the utility room. Is this a back drafting condition? Is the flu properly installed? Etc.
I say time and time again, it is vitally important that you fully understand exactly what you’re pointing the camera at when using thermal imaging. You must understand what the baseline should be and you must understand the working components to conceptualize what is happening in the thermal scan.
There is a lot of things you can do with a thermal camera, but you need to use some restraint in your business practices do not claim to be able to do them all just because a manufacturer or trainer says it can be done. Stick with what you know.
Has anyone taken a hammer to a circuit breaker lately?
If you don’t know what’s going on inside, it’s difficult to visualize the thermal signature.
My interpretation of the scan posted is that there is a bad circuit breaker connection at the line side bus. The electrical circuit is not overloaded but it is loaded. The thermal pattern of the other circuit adjacent breakers, appeared to be heat radiating/conducting from behind these circuit breakers.
And yes, a 66° indirect temperature rise in a residential service is substantial and requires immediate evaluation.
When trying to determine if the circuit is overloaded, you must include a large portion of the wiring throughout the panel. In this scan, there’s not very much wiring in view for this evaluation. It is best to take multiple scans at different ranges/angles when you have an apparent anomaly.