Turn off power at the breaker
Verify power is off with a non-contact tester
Identify the common terminal on each 3-way switch (usually labeled COM or marked dark screw)
Identify the two traveler terminals on each 3-way switch (the remaining two screws)
Identify the hot feed (line) wire from the power source
Identify the load wire (to the light fixture)
Identify the traveler wires between the two 3-way switch boxes
If using 3-wire cable between switches:
Connect line (hot feed) to the common (COM) on the first 3-way switch
Connect the two traveler wires to the two traveler terminals on the first 3-way switch (either traveler wire to either traveler screw)
Connect the two traveler wires to the two traveler terminals on the second 3-way switch (either traveler wire to either traveler screw)
Connect the load wire to the common (COM) on the second 3-way switch
If using 4-wire cable between switches (common plus travelers present):
Connect the line hot to COM on the first switch
Connect the load to COM on the second switch
Connect the two travelers between switches to the traveler terminals on both switches
Connect ground wires:
Connect the bare/green ground wire to the green ground screw on each switch (or pigtail to the box ground)
Connect neutrals:
Do not connect neutral to the 3-way switch unless the switch is specifically designed for neutral
Cap and leave neutrals in the box if required by wiring method
Move wires into the box neatly and tighten terminal screws
Ensure no bare copper touches other terminals
Install switch into the box and tighten mounting screws
Restore power at the breaker
Test operation by toggling both switches to confirm correct switching
If the light doesn’t work or works opposite:
Swap the two traveler wires on one of the switches (only travelers) and retest
If still incorrect, confirm which wire is line and which is load, then rewire COM accordingly