That’s pretty confusing. One part of the code says you can run (9) #12 in ½” EMT. But after (3) 20-amp circuits (6 conductors), I’d have to pull #10 conductors for any additional circuits due to the ampacity derating table.
Assuming all is #12 so I don’t get further confused… On this one particular run, I would like to pull at least (3) circuits through (1) section of ½” conduit.
b)garage door openers
That’s (6) conductors initially. However, one of the circuits will be switched (shop lights) into two zones… so there is going to be an extra hot making it (7) conductors. So, according to the code I’d have to pull that 7th hot as a #10?
Now in reality, the furnace and the door opener circuits will be #14, 15-amp, so I will probably be alright, but I want to stick to your 20-amp example so I can better understand this. After the shop/garage is wired, I will have the rest of the house to do. Because I’m the guy bending and installing conduit, it would obviously be of great benefit to know how to plan additional runs.
Thanks to you, and all others, for your expertise!