Found a trick for wiring 3-way switches that saved me 45 minutes on a job in Akron last Tuesday

I've always struggled with keeping the travelers straight on 3-way circuits, especially in old houses where the colors are faded or just random. Used to take me forever with the meter checking every wire. Then an old timer I was working with showed me to just take a sharpie and mark the common screw on the old switch before you remove it. Sounds stupid simple but I never thought to do it. Saves so much backtracking. Anyone else got a simple marking trick like that?

3 comments

3 Comments

lucasschmidt1mo ago

Huh, I gotta disagree. That different colored screw thing only works if the house was wired sometime this century. Half the old switches I see have screws that all look the same after years of dust and paint. Marking it with a sharpie takes two seconds and saves you from guessing which one is the common when they all look like rusted junk.

nora_park1mo ago

Gotta push back a little on marking the common screw, since most 3-way switches actually have the common screw labeled on the back or stamped right into the metal. You can save even more time by just looking for the screw that's a different color, usually black or brass, instead of grabbing a sharpie. Still, I get that in really old houses with all black screws, marking it is better than guessing and pulling out the meter.

ninas671mo ago

Take a step back and think about how much time you're wasting digging for a sharpie in the first place. Most old timers I've worked with just look at the wiring pattern - the common screw is always the one that's alone on one side, while the travelers are paired up. If you're working in a house with all black screws, that's rough, but marking it still doesn't beat just memorizing the layout. I've pulled switches out of 1950s boxes where the common screw was so caked in paint it looked exactly like the others, but the wire arrangement told me everything in two seconds. Sharpie ink rubs off with dirt or sweat on your gloves anyway, so you end up second guessing yourself later. Ngl, learning to read the wiring is faster than any marking trick once you do it a few times.