This article was first published in the May 2016 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content ...

I'm wiring a new 220v outlet (with the help of my step-father) but I'd just like to make sure he is doing it correctly and that I understand a little bit more... Basically, I'm trying to wire a new ...