I'm installing new electrical boxes and wiring to a 3 way light switch. I had marked where the wires go but somehow while running the wires into the box the labels fell off. What is the best way to trace these wires down with a meter so I know where to hook them up on the new 3 way switch? One wire should be hot, and the other two should toggle right? Or does the hot wire toggle depending on where the other switch is set?