Does any one have any guide as to what temp above ambient would be considered as an anamoly on bus bars ?

The bus bar photos were taken from below on the walkway.

Ambient temp was about 75 F. Two bus bars were close to this temp. The third bus bar was 85 to 90 F.

The customer is asking at what temp is there truly a problem. From my experience most bus bars have been within  5 -10 F from ambient.

Thanks,

Mike

Mike,

I don't think there is a chart for this. If this were a 1000A circuit with a load of 250A the temp would obviously be lower than if it were near its capacity so temp rise above ambient doesn't have a lot of bearing on this. I would suspect the buss bars should be close to uniform in temperature to each other. There could be serveral causes but the first thing I would want to do is find the distribution panel feeding the buss and measure the current. Load imbalance is the first thing that comes to mind so checking the current would answer that question. Hope that helps.

Jeff