3 Way Switch Wiring Diagram Power At Switch. The diagram below will give you a better. Since there is already power to the existing switch in the garage, the underground wire from garage to house will be the switch leg only.
Shut off the power at the service panel; connect the hot wire to the common terminal of your replacement switch, and the blue-tagged wires. They are always installed in pairs and use special wiring connections. They've also remained largely unchanged for decades.
There is a common sense reason for.
Purchase a multi-meter or power wand to help determine which wires are line, load, traveler and neutral.
Many of the conductor connections will be. Three-way switches allow you to control lights from two locations - from two doorways to a room, from the top and bottom of a stair, from house and garage, etc. Three way switches each have three connections and are used in tandem.