The alternate 3-way switch wiring configuration (California or West Coast) was used as a way to wire 3-way switches and be able to supply line voltage to either switch. This configuration is no longer allowed as the neutral is not present in each switch box.
Conventional 3-way wiring is not very complex. With conventional wiring, the line (line voltage) connects to the common of one switch, while the load (light) connects to the common of the other switch. However this alternate wiring configuration could cause confusion.
Alternate 3-way wiring configuration is described below.
A traveler terminal from each switch are connected together.
A common terminal from one switch and the other traveler terminal from the other switch are connected together and connect to the line voltage.
The remaining common and traveler terminals on each switch are connected together and connect to the load(s).
It may be difficult to determine which configuration is present in any 3-way wiring configuration. When replacing a switch, the new switch needs to be connected the exact same way as the old one. If you have any problems with your 3-way switches, it may be best to call an electrician.
Alternate 3-Way Switch Wiring
Alternate 3-Way Switch Wiring Diagrams
Line voltage can be connected to left or right switch