Confused at times
Member
- Location
- San Francisco, ca, USA
Ok, so this one always catches my attention when I ask another electrician 'why' in regards to a code question. The typical response can vary but usually is ,"it's how we always did it!." Ok fair enough, we know green = ground, it's in the code book but who can remember where? (Not a real question)
Anyway now to the reason of this post. I was talking to another journeyman about sizing feeders for a 100amp 4wire subpanel that is about 60ft away(120/208). I was taught to use #2's with with a #8 ground. (The joys of using memory and not looking it up) Fair enough. But I had this moment of curiosity to look up some code. So memory tells me to go to table 310.16 for feeders and 250.66 for the gec. To be honest I'm not sure I've had the desire to look into a code book for years.
I've got an older code book (think I heard 310.16 is gone) and notice that #3's are rated at 100amps at 75c. I do a double take and say to myself 'odd'. Then I realize break times over and I gotta get back to work.
The next day I'm mulling it over and wonder why the hell we install #2's and not #3's. any code gurus have a reason behind this? Can we use #3's? I assume I'm just forgetting a fundamental, probably derating.
Anyway now to the reason of this post. I was talking to another journeyman about sizing feeders for a 100amp 4wire subpanel that is about 60ft away(120/208). I was taught to use #2's with with a #8 ground. (The joys of using memory and not looking it up) Fair enough. But I had this moment of curiosity to look up some code. So memory tells me to go to table 310.16 for feeders and 250.66 for the gec. To be honest I'm not sure I've had the desire to look into a code book for years.
I've got an older code book (think I heard 310.16 is gone) and notice that #3's are rated at 100amps at 75c. I do a double take and say to myself 'odd'. Then I realize break times over and I gotta get back to work.
The next day I'm mulling it over and wonder why the hell we install #2's and not #3's. any code gurus have a reason behind this? Can we use #3's? I assume I'm just forgetting a fundamental, probably derating.