Motors

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gabo13

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Puerto Rico
Hi, i was watching a video of Mike, precisely of motors, and i note that in all examples that include conductor ampacity determination, the selected column was 75 degrees. I thought that if the circuit was rated less than 100Amps we should make our calculations based on the 60 degrees column. I know that if the terminals are rated to 75 well we use 75 column but i have that confusion about the 100A rating.
Thank you
 
If over 100A you can assume 75C. If under 100A you must have evidence that the terminals are rated for 75C (marking/listing).
Very straightforward.
 
GoldDigger said:
If over 100A you can assume 75C. If under 100A you must have evidence that the terminals are rated for 75C (marking/listing).
Very straightforward.
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Exactly, at the end 75 degrees conductor are much easy to find on the market than the 60, so i think that in some cases even if you make your calculations based on 60, you end up installing 75 degrees, example: based on 60, the conductor is #6 AWG but you installed #6 AWG 75 degrees because availability. Thank you!
 
I have seen only one 60 deg c rated device, it was an old dryer recept from my house, it probably dated from the 50's.
 
Unless your item is more then 20-25 years old it probably has 75C terminal rating, especially circuit breakers, safety switches, motor starters and other similar items.
 
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