This image was taken from the back of a Square D I-line switchboard.  It is rated at 4000a with a 1400a load.  the hot spot is the phase support member which has a temperature of approx. 106 dgrees f.  I checked for a load imbalance, the buss to the right of the support is the neutral buss, and found it is only about 75a.  My concern is that if the load increases to 80% of the 4000a rating then the temperature of the supprt should also rise.  The support is very close to the A B & C phase buss to the left and the support is also holding the line side buss for B & C phases in the incoming line cabinet.  I showed the images to the engineer on staff and he was not concerned and stated that no one had located this problem on previous inspections so it must not be a big deal.  I believe the B phase buss is inducing current into the metal support and wanted to see if anyone had any input on recomendations for the problem.  Even if nothing is done by the on site personnel I still want to document the problem correctly incase there are future problems caused by increasing the load.  Thanks all and have a safe day.

 

Warren Garber 

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Warren C. Garber
Level III Infraspection Institute Certified Thermographer

I'm not 100% sure that this is induction, I would like to see a visual.

106F is not that hot, and it may not be something to worry too much about. First off it is not hot enough to burn anyone, secondly, the metal is unlikely to change any of its material properties and thirdly it is not hot enough to be liklely to cause any secondary damage. It is something to be aware of, and may need to be monitored. It might also be worth investigating if it is something that has only developed, as the engineer suggested.

Of course this is based on the measurement being taken from a high emissivity item.

 

It was an electrical inspection so the emissivity was laft at 1.0 throughout the inspection.  I did not calculate for background or use a contact probe to find the exact emisivity, however the Sqare D flat gray of the support is probable between .90-.95.  I really do not see any other source for the heat.  There was another switchboard of identical layout in the room with a much lower load that did not show any signs of temperature rise above ambient.  There is no reflective heat in the cabinet and I also change my viewing angle to rule that as a source out.  I have the visual at the office and will see if I can post that next week.  Thanks for the response.

 

Warren Garber

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Warren C. Garber
Level III Infraspection Institute Certified Thermographer