/diy/ - Do It Yourself

>>1430418
Question that maybe one of you guys can help me with:

When I'm working on things like restoring a power tool or maintaining my car, or even just using a multimeter, black is common, red is power. Just about everything I can think of is always coded as black = negative and white/red = positive. Why is it that when I'm replacing an outlet or light switch that black is live and white is common?

I'm confused as fuck about this and whether I'm watching Bob Vila telling me that black is positive and white is negative, or I'm reading it in an online article

>https://www.angieslist.com/articles/what-do-electrical-wire-color-codes-mean.htm

I don't get why it isn't standard. If I'm working on a power tool from the 1950's, I look at the cord and find a black common, white live, and green ground. If I'm working on my car, I have a black common connected to the frame of the car, and a red live. If I'm working on a fucking wire connecting a 9v battery to my garage door opener panel, I have a black common, and a red live connected to the little terminal pad. If I'm working on an RC car, same deal, black common, red or white live. Why the fuck is it that I then go into my house to replace a light socket and I have to then think backwards and wire black live, and white neutral when everything else including my fucking multimeter uses the other standard of color coding?