AFCIs hot on thermal

I’m beginning to train on thermal imaging and go through courses on it and I’m pointing my camera at things to start seeing how they look as I go.

The AFCIs in my houses panel are all hot spots. The temps are still pretty low but big difference from the other breakers.

Can anyone share what I could deduct from this, if anything? Thanks!

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It’s normal for AFCI breakers to run hotter because of the extra circuitry inside of them used to monitor the arc’ing, if any. The AFCI breakers can get hotter than ambient temperature by 65C, do the math :slight_smile:


That makes total sense, thank you. I knew that AFCIs are constantly monitoring current conditions, so it makes sense they run hotter than standard breakers which only sense overloaded circuits.

The AFCIs are “active” devices, they are operating and have a current flow even when the circuit they control is open. Switches and breakers are “passive” devices, they are merely conductors when they are closed.

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Get some real training when your done with the free stuff.
You can’t just put the camera on auto and go. In your pictures things look like everything is on fire. That’s because your in the Auto Mode. Also turn off the MSX. It makes you think things are hotter than they are. Some things (like AFCI/GFCI breakers are supposed to be hot. You need to know what your pointing your camera at, because the camera will not tell you what it is (Blue is not moisture. It is just the color the camera assigns to the spreadsheet data it collects, based on how you set up your camera.). Something blue can be 195F if your in the attic, and that is getting too hot for the wire.

As for your breaker thing, your spot meter is in the wrong place. Your too far away for that camera. All the pixels in that circle average each other and your not getting an accurate reading. You are also taking an ‘Indirect Measurement’ which means the buss on the other side of the breaker could be from a 2,000 degree arc. So the point and go technique does not work with IR.

How hot is too hot? What is the max temperature rating for the insulation on that wire? Look it up. It’s closer to 194F than 68.4F. You need to know how hot or cold things are supposed to be under the current conditions of your testing.


Great advice. Thank you.


The topic of Infrared Inspections of Arc Fault Circuit Interrupters was covered in the Tip of the Week section of the content-based website, IRINFO.ORG. This Tip and hundreds like it may be viewed for free.

Hope this helps.