Causes of heat at main electrical wires

[Scott Dana]

See photo link below. I was told by an electrician that this heat/resistance can be caused by a loose wire or possible load problem. Does that sound right? Is this something you guys call out and if so, what wording do you use? Thanks.

http://www.danahi.com/images/IR_1272.jpg

(Not the hot condensing unit breaker, the main electrical wire above it.)

[James E. Braun, CMI]

Also possibly a bad main breaker. Have an electrician stick a meter on the circuit and track it down.

[Scott Dana]

Stick a meter on which circuit? The one for the hot condensing unit? I was not thinking that was related since those always run hot when in operation.

[Jeffrey R. Pope]

Also, possibly a heavier load on that pole. I see nothing abnormal in that image.

[Chuck Evans]

You need to tune your image and place your pointer on the hot spot so that you can determine temperature differential over ambient.

I don't see any drama here.

[Scott Dana]

I have called this type of thing out before, and even had a client get back in touch with me saying how great of a catch it was as the line was loose and almost fell out at the connection. So I'm confused as to how I can determine if/when it's a problem. So far most folks on this post as saying it's not an issue.

[Brian A. MacNeish]

Originally Posted by Scott Dana

See photo link below. I was told by an electrician that this heat/resistance can be caused by a loose wire or possible load problem. Does that sound right? Is this something you guys call out and if so, what wording do you use? Thanks.

http://www.danahi.com/images/IR_1272.jpg

(Not the hot condensing unit breaker, the main electrical wire above it.)

Geez, if that breaker is 110-115*F, in some parts of the country the ambient air would be hotter than the terminal. Yes, it may be hotter than ambient but that doesn't mean there's a problem. Most wire today is rated at 90*C or about 150*F. Many regular breakers are rated to operate in 140*F ambient air.

[David A. Andersen]

Where did you go to school?

Interesting that the electrician knows more than you do.

Yes, he is correct (but you should know why).

You should never point a TI camera at anything you don't understand.
In the case of electrical applications, there is a wide assortment of things you can tell from the scan (not just that it is hot).

How did you come up with the emissivity level?
Did you correct for reflected apparent temperature?
How did you do that?
What was the amperage on the circuits?
What was the load correction factor?


As you can see, when you change E the span and temp changes ...

[William R. DeVries, CMHI]

out of curoisity what is the manufactures load and operating temp, its usually stamped on the side, thi swill tell you if there is a problem. I see nothing out of the oridanary in the picture to warrent a electrician coming in. Were you able to see where the circut was going and what was drawing from it.
Also as David said what were the other factors, RAT FORD corected temp, also you need to put your spot on the spot you want to measure, this also makes it easier for people to answer questions cuz we have more info. as a side note were you wearing your ppe when you put your camera in the panel.

[John McKenna]

Originally Posted by Scott Dana

See photo link below. I was told by an electrician that this heat/resistance can be caused by a loose wire or possible load problem. Does that sound right? Is this something you guys call out and if so, what wording do you use? Thanks.

http://www.danahi.com/images/IR_1272.jpg

(Not the hot condensing unit breaker, the main electrical wire above it.)

The heat levels from high emissivity plastics breakers and romex
do not look alarming. Your E setting is close enough for this material.

The PATTERN of heat build up coming coming from the service
wire on the main breaker may be a concern. You would not
normally see the large service wire showing much heat if there is
only one breaker under a normal load.

If there are other breakers loaded, all on one side of the panel,
then your pattern may be normal. If breakers are loaded on both
sides of the panel, then the ONE service wire heating up may indeed
be a load distribution issue or corrosion, as your electrician noted.

An electrician would need to call out the exact defect, after testing.

Sometimes a heat issue will be mild as it moves toward more
heat over time, as the defect continues to degrade. Many panels
have minor distribution issues and people don't know it. It ends
up using more energy, but does not rise to the level of a safety
concern in many cases. But corrosion at any stage should be corrected.

Some issues can be seen by the PATTERN and some by TEMP.
David's comments would give us even more precise details.

[Scott Dana]

Originally Posted by jmckenna1

The heat levels from high emissivity plastics breakers and romex
do not look alarming. Your E setting is close enough for this material.

The PATTERN of heat build up coming coming from the service
wire on the main breaker may be a concern. You would not
normally see the large service wires showing much heat if there is
only one breaker turned on.

If there are other breakers loaded, all on one side of the panel,
then your pattern may be normal. If breakers are turned on all
over the panel, then the ONE service wire heating up may indeed
be a load distribution issue or corrosion as your electrician noted.
Sometimes the heat issue will be mild as it moves toward more
heat over time, as the defect continues to degrade.

Some issues can be seen by the PATTERN and some by TEMP.
David's comments would give us even more precise details.

Thanks John, that's the kind of info I was looking for. Incidentally, I'm still interested in taking your course one of these days. Hope things are well in Texas.

[David A. Andersen]

I think you should take Johns course sooner rather than one of these days unless your just "looking around" during your inspections.

Do us a favor and don't be one of those that give this industry a black eye because of bad information.

You also may get the bill for the electrician if they don't find anything.

[Chuck Evans]

OK here's another look at it.

Delta 1 compares the temps of the two legs. If they are under similar loads you can compare to one another (this is not a good assumption here because we don't know the loading, but we'll use it for illustration). The Delta between two feeder connections is 5.0C (low end of NETA priority 3)

Delta 2 compares the hotter leg to the ambient temp in the panel using avg of the Ambient labelled box. The Delta between the warmer leg and ambient is 5.1C (NETA priority 4)

Delta 3 compares the warmer breaker to ambient. The Delta between the two is 11.4C (very bottom of NETA priority 3)

As mentioned previously, I don't see any drama here. None of the temps are anywhere near max rating for components (the "hot" leg is scarcely above body temperature) and the Deltas come out low on the NETA scale. I think the NETA scale is a bit too conservative anyway since they call for investigation at 1C Deltas. I wouldn't even mention this at all in my report.

I have a different opinion than David. I think you should point you TI at everything you have a chance to and use that as a method to learn how to interpret what you see. However, I don't recommend you marketing thermography services or reporting observations until you have a lot more experience and knowledge with IR concepts, your imager AND software. Just as buying a point and shoot digital camera and learning how to snap pictures does not make one a professional Photographer, buying a TI and pointing it at stuff does not make one a professional Thermographer.

As for training, I would go for a course that has an accredited certification program.

[Jason Kaylor]

I love that you use NETA, Chuck. The are various PDM scales like NETA. I highly recommend all of you using some form of standardized scale like this is your reporting. It also takes a lot of guess work out of reporting and image interpretation.

Although some responces in this thread are borderline to just being critical of the OPs question, Chucks responce has brought to light some valuable info for all.

FYI these PDM reference scales are covered in Level II training. Yet another good reason why many here are preaching the training even though some think it is just some way for companies to milk inspectors.

JJ

[John McKenna]

Also... corrosion (or a damaged lug, loose connection, etc...) will usually create a pattern that indicates a localized hot spot is building up, instead of the entire length of the conductor glowing with heat (it is normal, in many cases, to see the entire length of the conductor glowing with heat when under load - up to a certain point).


Even if the temp. is not that hot, this is a pattern that I would call out for electrical evaluation and repairs, as needed.


If the main service wire has a little heat, as above, over the entire length of the conductor, then it will probably be more of a distribution signature, and not a localized corrosion hot spot. We see this many times and it is usually not an issue that rises to the level of a safety item (unless other factors can be introduced). I would leave it to an electrician to actually call out something as a distribution issue that needs repair. With a different set of loads placed on the entire system, then it may not have a distribution issue at all. It is very common to see panels that are a little out of balance.