Learned this one early on:
I saw an old electrician scratching his head & kicking the ground in about '75. Seems he had put all his 4 wire homeruns in 1/2" EMT on the store he was building. Los Angeles County was still going by '68 Code's wirefill, which only allowed 3 #12 in a 1/2" conduit. (7 years later)
Yes, they made him tear it all out. Seems like inspectors reject change of any kind until they're forced to accept it.
