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temperature rise of a fully loaded breaker terminal

temperature rise of a fully loaded breaker terminal

temperature rise of a fully loaded breaker terminal

(OP)
Anyone know what the normal temperature rise of a fully loaded breaker terminal should be? I understand that the connection is (in most cases) rated to work safely up to 75 Degrees C.

I need to infrared scan hundreds of misc lighting and power panels mostly consisting of 20 amp branch circuits. Ideally I would remove all the panel covers to do this. But with limited resources that is no going to happen.

Instead I would like to use a threshold value of a breaker face being above adjacent breakers. Right now I am using 20 degrees C rise. If a breaker is 50 C and most of  the other breakers in the same panel are 30 C I tag that panel for inspection. (Pull cover, check breaker terminal tightness, visually inspect wiring, and check loads.)

I need to know what temperature rise would be normal on a 20 amp breaker at a 16 amp load over the same breaker with no load. Also would the same temperature rise apply to larger breakers? They have more load, but also have larger connection areas.

I assume breaker designers have a temperature rise target for normal maximum load that is well below the safety limit of 75 degrees C.

Thanks,
Andy

RE: temperature rise of a fully loaded breaker terminal

I don't think there is going to be a front-of-the-breaker temp rise you can use.  You will probably need to just set your own standard for that.  By examining a CBs body temperature under the cover after noting its face temp, right after opening the door cover.  

RE: temperature rise of a fully loaded breaker terminal

The terminals of breakers are always rated below the temperature rise of their conductors. For example it would not be unusual to see 20A breakers rated for a 50C rise when using 60C insulated wire and a 55C rise with 75C conductors.

Also, it it not unusual for the terminals to normally be "cooler" than the breaker handle.

RE: temperature rise of a fully loaded breaker terminal

I think the method you are working with will give you good results. I suggest that when you remove the cover that you scan all connections before tightening or disturbing them. Then do some checks with your ammeter. You will soon develop a feel for normal temperatures and abnormal temperatures. By the time you finish this project you will be the expert. I hope you will have time to share a summary of your results with us.
yours

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