Checking temperature of breakers

It seems that several inspectors are checking the temperature of breakers in panels…

Here are some things you should understand and be able to explain if you are offering this type of inspection:

Do you realize that a bad connection can exist at a breaker or a problem at a load device that will cause the breaker to get hot AND it will not always indicate a high temperatue when you measure it?

Also do you know what the normal temperature would be for a 30 amp breaker feeding a water heater that has been heating for 45 minutes?

Do you realize that a warm 200 amp breaker in the top of a panel does not always indicate a problem with the breaker or excess current? Do you know what else could be wrong?

Bruce - I typically test the breaker temps in relation to one another to provide some frame of reference.

I do not claim to know what the normal operating temp is for any breaker - but I do know that when one jumps through the roof - it isn’t good. I am not relying on the temp as the sole method of identification of a problem, but it doesn’t hurt either.

If you have any information to share with relation to standard operating temps, I would be interested in reading it.

If you don’t know what is the common temp or the minimum or max temp, how can you say diffenitively it is abnormal?

The important thing to remember is that any temperature reading will first require each and every circuit to be adequately loaded for a period of time (at least 30 minutes) then the temperature check made.

I doubt anyone is doing this, so remember to state in your report that all circuit breakers were not checked for abnormal heat during operational conditions.
ie. if you report one hot breaker and did not properly load, wait and test the others you only did a partial inspection for hot breakers.

I do not have any data for standard operating temperatures and do not believe it exists due to many factors such as type of panel, manuf. of breaker, size of wire, ambient temperature, load, load time period, location of breaker in the panel, temperature of adjacent breakers etc.

Test the amp draw on the ones that are hot. Compare to 80% of the breaker rating. If it is not drawing much current, there is something you need to look into.

I must be missing some thing where am I to get the time to check all these things some are talking about .
Why would a home inspector get into checking water pressure water flow per minute ,voltage drop,
current draw, slope of the roof ,How about getting into poor power factor and how to correct it also.
Camera in the chimney how about a bore camera too .
I take about three hours to do my inspections.
Some people must be super man to do all the things people talk about.
How do you transport all the tools you must have and how do you pay for them .
This must just dumbfound some of the new inspectors in what he must learn and carry
I still do the simple inspection with the tools I can carry in my pocket .
Flush the toilet ,turn on tap water comes out must be OK .Check water temp and note it
Marble on the floor little movement slope is fine .
Feel the breakers with back of my fingers not to hot A OK .
Turn up furnace it blows warm are after a few minutes
Thats Good. when it shuts down try AC it starts check split good air movement ,
Thats good.try Bath exhaust Toilet paper test air is exhausting , Thats good .
I do not check amount of air being draw out of Bath exhaust or how much air comes out of register
or what the voltage drop is at Hot water tank .
I still like the KISS (keep it simple stupid ) .
There are a million tests you can get into if you want .
Not for me others may agree.
Roy Cooke Sr. …

I agree with most of that Roy,

I just started this thread to help the other guy’s that are using test equipment without knowing how and why and what to and not to report about it.

If one NACHI inspector gets in the news over a major problem then we all could look bad.

Taking those sort of measurements is way beyond any SOP. If they are not part of the SOP how can we all look bad. Its no different in my opinion than reporting on heat loss calculations…

The value would be in finding something that you should be giving a better visual inspection of. There have been enough pictures of overheated lugs here for you to see what one looks like. The thermo scan might actually let you be able to say a loose connection was fixed too. If the suspect circuit is loaded and the terminal is cool, they fixed it but it still shows the wound.

Here is a pic of a thermo camera I took a few weeks ago.

My infrared thermometer picked up the same thing.



But if its drawing current as it should be, would it not be heating up anyway? Just because its warm does not indicate a problem does it?

Used infrared thermometers all the time when I did industrial electronics.

Regularly found loose breakers connections with no other indications except an elevated temperature reading.

I didn’t need to know the “operating temperatures” or what the temperature of a breaker used on a water heater under load should read.

Resistance becomes heat. Since a breaker connection should not have resistance, all the breakers should read roughly the same temperature. If I read 80, 82, 83, 114, 85, I can be relatively sure I have a loose connection. No breaker characteristics needed.

I choose to use the infrared. You may not. Doesn’t make either of us wrong. It’s just another tool in the box.

Can someone check a water heater breaker that has been heating for at least 30 minutes and has tight connections and tell us the breaker temp. and the ambient temp please?

I am guessing over 100deg F at ambient of 75F would be normal.

I just checked my breakers with my infra red therm. and the basement temp is approx. 53 F. The breakers and the A/C (running) were all reading 57-58 F.

I don’t have an electric water heater so I can’t test this for you, but over 30% variance in temperature between 2 breakers in the same panel would be anything BUT normal.

Even 200 amps pulled through a breaker should not increase the temperature of that breaker significantly over ambient. If so, there’s an impedance issue to be resolved.

It is normal actually. The circuit breakers I see are mostly GE, Square D, Murray, Siemens. They all run significantly warm with over 60-70 percent load.

An air conditioner or heat pump is not a good load to use, ie. 30 amp breaker will typically have 11 to 15 amps flowing during operation. This is why I wanted some comments on water heaters.

Low ambient temperatures will cool the breakers also. The best way to verify this is to do it with ambient around 70F.

Also the HVAC is an inductive load where as the water heater is a resistance load. HVAC breakers are required on HVAC circuits because of this.

David my breakers on my A/C do not appear to be specific HVAC they are normal breakers. Have never had a problem. Most times the breakers are upsized to accomodate the motor start up loads?

Does the CEC or the UL standard in Canada mention “HACR” types of overcurrent devices? I believe that most AC labels call for an “HACR” breaker or fuses.

See the catalog for some specific infotmation covering this.

Well said Roy! Completely agree with that.who has the time on inspection to check breaker temp ratings etc! I use the thermal for quick reference only to see if anything jumps out but am really careful about calling stuff out you can get in big trouble. Agree with good inspecting procedures fingers on breaker sides etc we are generalists leave the indepth technical stuff for the specialists! Can’t waste time on inspections pondering keep it simple and not sure recommend a qualified electrician to evaluate