You're right. 60 degree is unreasonable. Even for just a question.
Let me phrase it better....
lets say 200A panel, but lets assume the panel is not in the ambient room, just the supply wires run through somewhere, where it will be 40 degrees ambient. Whats the min size coppers we can use to supply this?
Now, here's my confusion, and it's probably silly. But i need to learn the right way.
So, I would goto Table #2. I see that 210 A is the min rated wire to supply at least 200 A. Which is 3/0. I am not 100%. But I feel I should use this, as it doesn't state that this is a residential property. In which case if it did, I would use 2/0 rated for 185 A which is allowed in homes/individual dwellings.
Now, I feel I need to take that 210 A rated wire and do 1.25 x for continuous load for my panel. Then, I need to factor in the ambience for the wire at 40 degrees. Which is / by .9 using Table 5A.
At this point, I would get: 291.2 A. This leads me to 300Kcmil wire rated at 295 Amps. The issue I have is, that is not one of my multiple choice answer choices. So something is wrong in my way of thinking.
If I use a panel "assumed" (which I don't want to do since it's not stated) for a dwelling, I can choose 185 A. Then, I can just / .9 for ambience and I get 205.6 A which falls into one of my choices.
There are a couple other ways of looking at this. But I'm sure you get the idea, and I don't want to make a winded post.
My answer choices are:
1/0, 2/0, 3/0, and 4/0 wire sizing.
