ECN Forum Forums Code Related Discussion Canadian Electrical Code Topics 100AMP panel in 60 degree ambient what size wire?

hmm.. would this be more appropriate?
heater 2500 / 240 = 10.4 AMPS. x 1.25 for continuous load = 13.
since 15AMP breaker is max 12AMP at 80% load.
Isn't #12 the more correct choice since it can handle up to 16 amp?

btw: I should probably thank you guys for going thru a couple of these with me, and tolerating the side tracking at times.

Sid:



A 'Thanks' would always be appreciated, IMHO.

I'm taking a backseat on CEC.

No, #12 is wrong.Stop there. That's your minimum circuit ampacity.

You did the 80% load thing twice. Once when you did 1.25 x load and then again when you did 80% of breaker.

Method 1 for a commercial
100 / .67 = 149.25 for resi service = 1/0

Method 1? Are you saying that all commercial 100 amp panels, in Victoria, (excluding derating for temperature) are fed with #1 awg?

When you determine the panel size, it might be based on 125% of the load, but the wire size isn't again increased. That would be applying the 125% rule twice. Once for the minimum circuit ampacity and a second time to the conductor.

Thank you. I get it now.
Here is a more interesting one....
I've got 4 x #10tw75 in a 41mm conduit. How many more #16tw75 can I fit into the conduit?
I go to table 9 and I get my max wire size (area in mm) for 41mm conduit in the 40% fill zone.
Then, I goto table 10 to get the area of #16 to calculate my fill, and I see there is no #16. It stops at #14. How can I get the area size of #16 TW75 wire so I may complete the question.?
Or is it a trick question? ie: some rule about having lower than #14 size wire in conduit, and needing some kind of separation?

No #3 is still good for a 100 amp panel but feed a 100 amp panel through a 60 degree ambient and derating factors can bump it up a lot.
I think it would be a hugely bad idea to put a panel in a 60 degree ambient as most of the breakers would trip at values musch lower than the number on the breaker.
What would the ampacity be for a 60 degree breaker in a 90 degree ambient? 0 amps

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.

bump... ^^^ anybody?