Warm spot near service entrance

Found a warm spot with the infrared camera. You can see the electrical service panel above. The heat is approximately where the main service enters the home. Wondering if anyone has any insight related to this. Is the temperature ok? Could there be a nail pinching a wire or something? I just can’t figure out what else could be causing this much heat.

10 degree F difference is nothing…

You might consider a building sciences class to help you with your thermal imager.


Like Larry said…

Was it hot outside? Was the exterior wall surface in the sun? Could be warm air entering the wall cavity from heated siding. Missing insulation around the service entry conduit plus missing caulk between the siding and conduit is a source of heated air. Steel or plastic conduit? Hopefully your service entry wire is encased in conduit, because a nail + service wire = lots of sparks.

IR tells you what heat differences are present, your job is interpretation.


Certainly a possibility, warm air leakage on an exterior wall.
Is that screen display say 31 degrees? Isn’t that 80 degrees +/-? Not that warm to me here in sunny FL.


31.2 at the top and 25.9 at the bottom. I wonder if the OP has his camera set to measure ℃ and not ℉.

If so, that would make it 88.16℉ at the top and 78.62℉ at the bottom…

1 Like

Yes, I would say so.

I converted ℃ to ℉.


I was making an edit when you hit “reply”. :wink:

1 Like

Likely door bell transformer. Move on. Next!

If that transformer isn’t in a box and is buried behind a wall, that’s an issue.

1 Like

I don’t like the looks of this.
Can’t see much on my phone.
Send me the radiometric file and I will look at it and tell you what it is. Requestaninspection@gmail.com


88.16F = 31.2C.
I concur. Nothing here.
Limitations. Can not see the object behind the drywall.
Don’t box yourself in of make presumptions.

2002 NEC 725.55(D) . Likely amended. The code reference is from 2002.

The transformer can be on the outside of the panel.
The conductors are required to enter a knockout space and be connected to a branch circuit or to an OCPD. The cables are isolated and terminations spliced and protected in the enclosure.

Right, I meant that it’s not just wire nutted and screwed to a stud. Every doorbell transformer here in The Villages is on the outside of the main service panel or in a nearby closet on the face of a standard 1 gang box.

It if were in a box, it’d have to have an access plate that you can actually access.

As mentioned above, we know we have a wall penetration here. What was the exterior temps on this day?

Sadly, it does not appear we will receive any additional information from the OP. It’s a drive by IR shooting.


Sorry David, but the file you sent me is not radiometric, or I just can’t open it with my programs.

I will respond with limited information to your questions and comments posted by others concerning this. Hopefully it will help.

Found a warm spot with the infrared camera. You can see the electrical service panel above. The heat is approximately where the main service enters the home.

As we look at heat, we need to consider the method of heat transfer; conduction, convection, and radiation. There may be a percentage of each, and the sum of all will equal 100%.

If we look at the construction of the wall and interior components conducting heat from the exterior, certain patterns will appear with different intensity and size. The smaller the transfer coming to the wall, the larger the anomaly becomes. This one is quite confined to a small area. It is also passing through half-inch sheet rock and two three-quarter inch pine boards.

There’s a lot of talk of outdoor air entering through electrical conduit etc. This type of heat transfer (which is primarily convection) will generally produce a very large thermal exception. Leakage from the conduit will be seen as heating up the stud cavity above and below the shelf.

There is a nail penetrating the pine boards, sheet rock, and the corner stud. Which by the way is where wires are connected to the framing most of the time. The nail acts like a thermometer, indicating temperatures within the wall, not the exposed surface in the closet. You’ll also notice a halo around the nail, which is conducting heat away from the nail causing it to appear cooler then the adjacent sheetrock area where your measurement tool is located. It takes a lot of energy to do this.

Wondering if anyone has any insight related to this.

I have come across this several times where the electric panel cover screws were changed to longer, sometimes drill tap screws which penetrated directly through the cable inside the panel. This did not cause any breakers to trip. When I see this I put on the PPE, and open the panel where I find a screw hole in the electrical conductor. Not that your should be doing that…

Is the temperature ok?

The low temperature rise discussed here as being insignificant, can be very significant. There is a lot of insulation between the source of the heat, which could be several thousand degrees at an arking connection, but only shows a small temperature rise bacause of what it is passing through to be seen on the inside of the wall. This is because this is an indirect temperature measurement.

So now comes the question, did you open the panel and look for a more direct temperature measurement on any of the conductors? This would be a significantly higher delta T.

We do not determine if temperature is okay. There is a differential that doesn’t belong there. No matter how slight a temperature rise, if you can’t explain it, you should go look for the reason why.

Could there be a nail pinching a wire or something?
Yes, there is a very high probability in my opinion.

Next question, did you use a voltage sniffer to determine electrical connection?

These are all very important considerations which must be eliminated one by one, and what is left is the problem. A heat leakage into the stud bay will cause very large areas of temperature rise as viewed from the interior, regardless of its source. This thermal exception is extremely small for any of these. There is also a time factor involved. Electrical arc is very high intensity and does not travel the full depth of the wall system therefor a shorter time period. Air leakage from outside air is going to occur 24 hours a day, and because of the time factor the thermal exception will be extremely large with a very small Delta-T.

Just forget about the transformer thing at this point. There is more important considerations to deal with first.


Dear David:

Not sure where you stand on your original inquiry; however, I wanted to offer the following.

From your image, the span of the imager is set relatively narrow at 25.9 - 31.2 Celsius. Having a span of less than 6 Celsius degrees will cause imaged items to appear as highly contrasted and intense.

Your ‘hot spot’ appears to originate at the end of the unpainted shelf support which was most likely installed after initial construction. It is not uncommon for such supports to rupture the drywall tape thereby allowing air infiltration into the living space (assuming that they were properly taped during construction). Air infiltration into conditioned building spaces would appear warm in the Summer and cold in the Winter.

Although the span of your thermal image is very tight, the displayed thermal pattern resembles one typical of warm air infiltration. Should you eliminate air infiltration as the cause, I would recommend that further investigation be performed to ensure it is not an electrical problem such as David Anderson describes above.

I hope this helps.

Jim Seffrin, CMRP
Infraspection Institute