To wire a 2-way light switch to control a single fixture from two locations, you need two 15A SPDT (Single Pole, Double Throw) switches, 14/2 NM-B cable for the power source and light fixture, and 14/3 NM-B cable to connect the two switches via traveler wires. Terminology Note: In North America, a switch that controls a light from two locations is officially called a 3-way switch. In the UK, Australia, and New Zealand, this exact same configuration is called a 2-way switch. This guide uses North American NEC terminology and standard US wire colors, but the electrical principles apply universally.

Tools, Materials, and Device Ratings

Before opening any wall box, ensure you have the correct materials rated for your circuit. Most residential lighting circuits are 15-amp, 120V systems.

  • Switches: Two (2) 15-Amp, 120V 3-way (2-way) toggle or rocker switches (e.g., Leviton 5603 or Eaton 2033).
  • Wire Gauge: 14 AWG copper for 15A circuits. (If your breaker is 20A, you must use 12 AWG copper and 20A switches).
  • Cables: One 14/2 NM-B (Line to Switch 1), one 14/3 NM-B (Switch 1 to Switch 2), and one 14/2 NM-B (Switch 2 to Light Fixture).
  • Connectors: Red or yellow wire nuts rated for 14 AWG, and green grounding pigtails.
  • Tools: Non-contact voltage (NCV) tester, digital multimeter (e.g., Fluke 117), wire strippers (Klein 11055), Phillips screwdriver, and lineman pliers.

Mains Safety Protocol: De-Energize and Verify

WARNING: LETHAL VOLTAGE. Working on mains electrical (120V/230V) carries a risk of fatal shock or arc flash. According to the Electrical Safety Foundation International (ESFI), you must always verify a circuit is dead before touching any conductors. Never rely solely on a wall switch position to assume a circuit is safe.
  1. De-energize: Turn off the specific 15A or 20A breaker controlling the light circuit at your main service panel. Apply a lockout/tagout device if possible.
  2. Initial Sweep: Use your NCV tester to scan the faceplate and the wires inside both switch boxes. The tester should remain completely silent and unlit.
  3. Verify Dead with a Multimeter: Set your multimeter to AC Voltage (V~). Place one probe on the bare copper ground wire and the other on the black (hot) wire. The reading must be 0.0V. Repeat this between the black and white wires. If you read anything above 2V, stop immediately; you have turned off the wrong breaker.

Step-by-Step Wiring: Line, Travelers, and Load

A 2-way (3-way) circuit relies on two 'traveler' wires to carry the current between the switches. The internal mechanism of the switch routes the current from the common terminal to one of the two traveler terminals depending on the toggle position. Below is the standard NEC-compliant wiring method.

Step 1: Prep the Cables

Strip 3/4 inch of insulation from the ends of all black, white, and red wires. Leave the bare copper ground wires slightly longer (about 1 inch) to easily form a pigtail. Wrap two loops of black electrical tape around the white wire inside the 14/3 cable at both ends to re-identify it as a hot traveler wire, as required by NEC 200.7(C).

Step 2: Wire Switch 1 (The Line/Power Side)

This is the box where the main power from the breaker enters.

  1. Common Screw (Dark/Black): Connect the Black wire from the 14/2 power cable to the single dark-colored common screw.
  2. Traveler Screws (Brass): Connect the Red wire and the White wire (with black tape) from the 14/3 cable to the two brass-colored traveler screws. (Order does not matter between the two brass screws).
  3. Ground Screw (Green): Connect the Bare copper wires from both the 14/2 and 14/3 cables, along with a green pigtail, to the green ground screw on the switch.
  4. Neutral Splice: Connect the White wire from the 14/2 power cable to the Black wire of the 14/3 cable using a wire nut. Note: This carries the neutral through to the second box to satisfy modern code requirements.

Step 3: Wire Switch 2 (The Load/Light Side)

This is the box that sends the switched power up to the light fixture.

  1. Common Screw (Dark/Black): Connect the Black wire from the 14/2 cable (going up to the light) to the dark-colored common screw.
  2. Traveler Screws (Brass): Connect the Red wire and the White wire (with black tape) from the 14/3 cable to the two brass traveler screws.
  3. Ground Screw (Green): Connect the Bare copper wires from the 14/3 and 14/2 cables, plus a green pigtail, to the switch's green ground screw.
  4. Neutral Splice: Connect the Black wire from the 14/3 cable (which is carrying the neutral from Switch 1) to the White wire of the 14/2 cable going to the light. Secure with a wire nut.

Terminal Mapping Reference Table

Terminal Type Screw Color Switch 1 (Line) Wire Switch 2 (Load) Wire
Common Dark / Black Black (14/2 Line Hot) Black (14/2 Load Hot)
Traveler 1 Brass Red (14/3) Red (14/3)
Traveler 2 Brass White w/ Black Tape (14/3) White w/ Black Tape (14/3)
Ground Green Bare Copper + Pigtail Bare Copper + Pigtail

Verify, Test, and Troubleshoot Common Botches

Before pushing the switches back into the wall boxes and screwing on the faceplates, you must verify the circuit.

  1. Energize: Turn the breaker back on at the panel.
  2. Measure at the Fixture: Set your multimeter to AC Voltage. Place probes on the black and white wires at the ceiling box (where the light will connect). With both switches in the 'down' position, you should read 0V.
  3. Toggle Test: Flip Switch 1. The meter should now read 120V (acceptable range: 114V - 126V). Flip Switch 2. The meter should drop back to 0V. Test all four toggle combinations to ensure the light can be turned on and off from either location.
The Most Common Botch: The #1 mistake DIYers make is connecting the Line Hot (Black from the 14/2 power cable) to a brass traveler screw instead of the dark common screw on Switch 1.
Symptom: The light will only work when Switch 2 is in one specific position (e.g., 'up'). If Switch 2 is 'down', Switch 1 will do nothing.
Fix: De-energize the circuit, identify the wire bringing power from the panel, and move it to the single dark-colored common screw.

For deeper code compliance, always refer to the latest NFPA 70 (National Electrical Code) guidelines regarding switch loops and grounding.

Frequently Asked Questions

Can I use a 2-way (3-way) switch as a regular single-pole switch?

Yes. A 3-way switch is essentially a single-pole switch with an extra terminal. To use it as a standard single-pole switch, connect your Line Hot wire to the dark Common screw, and connect your Load Hot wire to one of the brass Traveler screws. Leave the second brass Traveler screw completely empty and cap any unused wire. Do not connect wires to both brass screws, or you will create a dead short when the switch is toggled.

Why does my light only work from one switch after wiring?

This almost always means the 'Common' wire and a 'Traveler' wire have been swapped on one of the switches. The common terminal must be the exclusive entry point for power (on Switch 1) or the exclusive exit point to the light (on Switch 2). If power enters a traveler screw, the circuit path is broken whenever the internal wiper of that switch moves away from the energized traveler. Double-check that the wire coming directly from the breaker is on the dark screw at Switch 1, and the wire going directly to the light fixture is on the dark screw at Switch 2.

Do I need a neutral wire at both 2-way switch locations?

Under older NEC rules, the second switch (load side) in a 3-way setup often did not have a neutral wire present in the box. However, NEC 404.2(C) (updated in 2020, 2023, and carried into 2026) requires a grounded circuit conductor (neutral) at nearly all switch locations to accommodate smart switches and occupancy sensors. This is why the wiring guide above routes the white neutral wire through the 14/3 cable from Switch 1 to Switch 2, ensuring both boxes contain a neutral splice. If you are upgrading an older home, you may need to pull new 14/4 cable or reconfigure your switch loop to bring a neutral to both boxes to pass a modern inspection.

What happens if I wire the travelers to the common screw?

If you accidentally land a traveler wire on the common screw, the switch will not function correctly, and you risk creating a short circuit depending on how the other switch is wired. The common screw is the 'feed' or 'output' of the switch mechanism. If a traveler (which carries switched voltage from the other box) hits the common screw on the load side, the light may stay on permanently, or toggling the switches may cause the breaker to trip instantly due to a phase-to-phase or hot-to-ground fault if the wiring is crossed.