Reading a 1970s code book and the wire gauge for a 15-amp circuit blew my mind

I was cleaning out my grandpa's garage in Toledo and found his old NEC book from 1978. Flipping through it, I saw that back then, a 15-amp branch circuit could legally use 14 AWG wire. I've only ever run 12 AWG for 15-amp circuits my whole career. It just felt wild to see the standard was different. How many of you have run into old wiring that followed this rule?

3 comments

3 Comments

john6501mo ago

Wow, @joseph_ellis85 is right, I still find that old 14-gauge wire in houses from that era (you just have to label the breaker panel clearly so the next guy knows).

joseph_ellis851mo ago

1978 NEC? 14 AWG was still common into the 90s.

diana_black1mo ago

Exactly, and @joseph_ellis85 is spot on. I pulled out so much of that old 14-gauge wire doing renos on my own house, a place built in '85. It's wild to see it still in there, just hiding in the walls. You really do have to be careful and mark everything at the panel, like john650 said, or someone could get a nasty surprise later. It just shows how long old building practices can stick around even after the rules change.