Hot breaker

[mnicholet]

This is the hottest breaker I have come across yet. It is a 125 AMP breaker for a electric furnace.

129 F

Can anyone confirm that this temperature is acceptable for a square D breaker?

[Frank P. Newman]

Originally Posted by mnicholet

This is the hottest breaker I have come across yet. It is a 125 AMP breaker for a electric furnace.

129 F

Can anyone confirm that this temperature is acceptable for a square D breaker?

Is that just a single pole breaker for such a load? What was the ambient temp?

[mnicholet]

That is a 240 V

Ambient temperature is unknown, this temperature was taken while the appliance was running full out.

[William Warner]

Your ambient temp is in the image you posted provided you correct for emissivity and reflection. Ambient temp should ALWAYS be known when performing thermal imaging in my opinion. Especially around electrical equipment. How can you accurately interpret the image without it???

I was taught UL standards 20 and 498 state a temperature difference between a component and ambient temperature of 30°C (54°F) may indicate a problematic component.

Other standards provide incremental temperatures and their corresponding degree of severity.

[Jeffrey Moore]

Mark,
Do you have an image with the deadfront off so we can see the wires?

You may also want to manipulate the span and look to see if the breaker
is uniformly "hot" verses just a smaller area.

Like previously mentioned it is important to have the ambient temperature
to be able to determine if the 54f delta is met. Without the ambient it is just
a WAG.

[mnicholet]

Square D technical support said the overprotection device should be running at 40 C / 104 F

[mnicholet]

Here is the latest find.

[David A. Andersen]

To answer your first question, I need to know what amperage draw that was on the circuit at the time you took to scan.

I need to know the ambient temperature of the panel.

From what I'm looking at, I don't see a problem concerning the temperature. But if you have a 125 amp breaker and your only drawing 40 amps, you got a problem.

Remember, if your comparing an indirect " un-corrected" thermal temperature reading of a circuit breaker, it is not the same as measuring a direct temperature reading with the ambient panel temperature.

The internal components could be 800 % higher than the indirect reading that you're taking.

From your follow-up posts, I will assume that you did not take the appropriate readings to determine "corrected thermal temperature". If you auto adjust your initial scan you can come close to your ambient temperature.

This is the problem that you encounter when you try to do quantitative thermal imaging when qualitative data is required to determine what a potential failure rate may be.

When we use "apparent temperatures" in quantitative analysis, we are reporting apparent issues. That is, unsubstantiated defects that may or may not actually exist.

Yes, I'm making rocket science out of button pushing thermal imaging training! However if you would like the answer, you must do what is required. (This is not directed at you Mark, rather the responses that will soon follow).

If you really want to know the answer to your question, you can e-mail me and I would be more than happy to provide you with a program to determine the load correction and how to use it.

[mnicholet]

Great information David and I highly appreciate it.

But to simplify, the discussion that I had with the Square D technical support stated the breaker should be running no higher than 40 C under a load. What is your take with this statement? Thank you.

[Jeffrey Moore]

Mark,

I'm not David but I'll just jump in.

40C is 104F. Todays temp here in AZ was 104F. We have most service panels on exterior of homes. Ambient temperature of the breaker without any load could exceed what you were told by the Sq D folks. Add any load at all to the picture and now what would the Sq D folks say. This is where ambient temp, load on breaker and all the other important stuff David has posted comes into play.

Also, if you could have images closer, and with dead front off it would help identify location of problem.(if one exists)

[David A. Andersen]

As Jeff pointed out, their 40C is based on a "design" ambient.

They did not give you all the information.

Also as Jeff pointed out, climb up on the breaker after you take a reference shot. Your SSR may average too much to get a good reading at that distance.

You need something like this to overcome the indirect aspect of the scan...

This is not a problem breaker by the way.

[mnicholet]

Pics with dead front off.

[Frank P. Newman]

Many (most?) electrical devices are designed to operate satisfactorily at a stated temperature RISE of no more than 40 deg. C ambient. So what they are really saying is that if the device temperature is no more than the stated rise over 40 deg. C, the device will be able to dissipate heat generated internally adequately. All that said, in a panel full of similar beakers, any breaker that is substantially hotter than those surrounding it bears further investigation, especially if the maximum temperature is observed to be at the connection terminal itself. An elevated temperature may be due to many factors, including load approaching the breaker's rating, but most such situations ae due to a deteriorating connection. Determination of the actual cause is outside the SOP.

[David A. Andersen]

So is the thermal imaging.
Should we do thermal imaging and then say that we do not have to determine the cause?

[Frank P. Newman]

Technically you do not have to state the cause, just the abnormal observation. Think of it the same as an appliance that does not work properly - that's all you know - not likely you know the cause.