hot light switch

in a inspection i did the other day i came across a light switch that was warm to the touch. the light was on for about two hours. ive never seen one get this warm. the hottest it showed up on the ir camera was 113. so the question is, is it normal for a light switch to get this hot? FLIR0146.jpg

Was it a dimmer?

What was the load on the switch?

103 or 105 isn’t “hot”.

Have you aimed your IR device on a wall transformer (doorbell, phone charger, etc.) or a cable/satellite box?


How “hot” do you think the light bulb is, on the end of that circuit?

As Jim asked what was the wattage of the load? If it’s only a few hundred watts or less I don’t think that the switch would be warm to the touch.

I would call it out

You’d call out an outlet at 103 degrees?

For what, doing its job?

Dimmers have a semiconductor or triac which heats up as electricity passes through it. When dimmers operate they give off heat normally at the metal plate and then through the screws as in the ops pic.

As Jim asked what was the wattage load. Ratings are from 300 to 600 normally and upwards of 1000. You can find the ratings on the dimmers front metal plate normally. Temps can get north of 140 degrees inside on some.

I don’t see where Taylor stated that this was a dimmer. That would certainly change the heat factor if it was.

The image looks like a snap switch to me (I know that there are dimmers that look generally like snap switches so this is not definitive). The temperature is not at all unusual for a dimmer, but may be for a snap switch. The thermal reading is also not from the source of the heat (i.e., it’s an indirect reading). The actual source of the heat will be higher, possibly much higher, than the cover screw. Add to that that the image is too far away from the screw for an accurate reading (again, the actual temperature of the screw is higher than indicated) and the imager is displaying a ~, so we don’t know the actual temperature of the screw and certainly not the source, only that both will be higher than indicated.

I would have investigated this further an removed the cover plate to see if I could pick up the source of the heat and just how high it was. I would also want to see how the switch was wired. I replaced all of the snap switches in my own home because they were back wired with 12AWG conductors and all of the switch bodies were cracked / broken, making for poor connection at the conductor. Some of these switches ran hot too and it wasn’t something you would want to simply ignore.

It was not a dimmer switch. The switch worked two 60 watt lights.

Then yes. I suspect there is an issue with it.

I agree, with a 1 amp load there should be no discernible difference in temperature.

Your right I should have read the posts more clearly so my apologizes go out to Mark for jumping the gun.

A 1 Amp load on a regular wall switch cannot create any noticeable temperature rise above ambient. I would say there is an issue.

#1 Taken with a FLIR C2. (properly tuned image?)
#2 Improper distance. (It’s hotter than it says due to SSR)
#3 Indirect measurement. (How hot is it really inside?)
#4 No load determined. (How hot can it become?)
#5 No further evaluation performed.
#6 What is the insulation rating on the conductor - switch?
#7 Can it burn you if you touch it?

You have no justification to make a call on something you did not evaluate under prescribed TI Standards.

You have a thermal camera.
You see funny colors in the camera.
It “looks” like a forest fire.
That’s all you have?

He did state that the load was 1 amp (120 Watts) and that the switch was warm to the touch. How does your #6 factor into this?

I don’t need TI to verify it. We all touch many outlets and switches. We can tell with our hands when one is warmer/hotter than usual. When I come across a hot one I call it out.

The “How hot is too hot” is about the Hot Component or conductor.
I find 105 F things all the time in Electrical - Mechanical Inspections.
What is the Insulation capacity/rating for Romex (if that is what was used)?

Is it everyone’s opinion that “something that feels warm” must be called out without determining what warm is, or how warm it may become? I find can lights and chandlers running hot all the time during continued use. Am I missing something?