Causes of heat at main electrical wires

[mjanuary]

request that a master electrican check it out. Yes, loose wires can and does make
problems and increases amps thus ups the electrical bill.
alum. wires are very bad about expanding and contracting making a problem breaker panel.

[Jim Seffrin]

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.)

Dear Scott:

Welcome to the exciting world of infrared thermography!

Although you do not provide all of the information needed for a detailed analysis, your thermal image is intriguing and noteworthy for the following reason.

The main panel lug on the right exhibits a thermal pattern typical of a defective connection. Notice how heat on the cable is localizalized to the area of the connection and appears to significantly cool within a few inches of the lug.

Assuming that there is not a significant change in the emittance of the cable, this type of thermal pattern is the classic signature of a loose/deteriorated connection. In making such a find, you should be careful in using temperature to qualify the severity of the problem. The operating temperature of loose connections can increase significantly with little or no warning and lead to catastrophic failure of the subject component.

In some cases, a temperature rise of 1 C can be indicative of a significant problem. Because one can never predict time to failure utilizing temperature, this component should be properly investigated for cause as soon as possible and proper corrective measures taken.

Furthermore, when diagnosing exceptions, one should keep in mind that maximum operating temperatures are provided for devices operating at 100% load and a specified ambient air temperature. For devices operating at less than full load and/or ambient temperatures other than those specified, it is possible to apply a formula known as TmaxCorrected.

In order to apply the TmaxCorrected formula you will need some additional information including circuit load, ambient air temperature, and an accurate operating temperature of the subject component. Although it takes a little more time to perform than a qualitative observation or an apparent Delta T calculation, this formula will enable you to ascertain whether a component is operating within spec for any given load or ambient temperature. Your double pole breaker would be a good candidate for applying this formula.

Proper use of the TmaxCorrected formula and several temperature severity guides, including NETA, can be found within the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment. This comprehensive 17 page document also outlines practices and procedures for safely performing infrared inspections of operating electrical systems. Copies are available from the Standards Section of Infraspection Online Store.

If you are interested in truly unlocking the potential of your infrared imager ($200,000 per year) and being capable of confidently diagnosing your imagery, I would suggest you take both a Level I and Level II training course where the above topics are covered in detail along with several other applications. Both courses are available as open enrollment classes or via our Distance Learning Program.

Please feel free to give me a call should you have any questions or if we can be of further assistance.

[Scott Dana]

Great info Jim! Thanks.