Okay, I have a 40+ year old house. The wiring is a mish-mash of old stuff and whatever the handyman the previous owner happened to hire that day put together.
So, I have a hallway light. I’m replacing very old switches with new ones. I hooked the new ones up the way the old one were and no joy. I bought a bunch of switches so I changed them out (just in case - I’ve bought new switches that were defective and still no joy).
So I started moving things around. Big mistake.
I now have the following (switches are two brass screws at top, 1 black screw on bottom):
Switch Alpha: Wires A, B, C.
Switch Beta: Wires D, E, F
Alpha is wired: Beta is wired: B A F D C E
So, I’m going to use “up” as towards the two screws and down towards the single screw:
Alpha Up. Beta Up Light Off, Beta Down Light On.
Alpha Down. Beta doesn’t matter. No light.
Alpha UP, Beta UP (light off): BA, BC, FD, FE HOT
Alpha UP, Beta DOWN (light on): Nothing HOT on either Alpha or Beta
Alpha DOWN, Beta UP (light off): BA and BC HOT
Alpha DOWN, Beta DOWN (light off): BA and BC HOT
So what the hell?!