The Direct Answer & Routing Decision

To wire 2 switches for one light, you need two 15A 3-way switches (Single Pole Double Throw), 14/2 NM-B cable for the power and light runs, and 14/3 NM-B cable for the travelers between the switches. The most foolproof routing method—and the one detailed in this guide—is Power → Switch 1 → Switch 2 → Light.

When planning your cable runs, the physical layout of your walls dictates your routing method. Use this decision tree to select your approach:

Scenario Routing Method Cables Required
Power enters at the first switch box Power → Sw1 → Sw2 → Light 14/2 to Sw1, 14/3 between switches, 14/2 to light
Power enters at the light fixture Power → Light → Sw1 → Sw2 14/2 to light, 14/3 to Sw1, 14/3 to Sw2 (requires re-identifying white wires)
Power enters at the second switch box Power → Sw2 → Sw1 → Light 14/2 to Sw2, 14/3 between switches, 14/2 to light
Concrete Default Pick: If you are running new cable and have the choice, always route power to the first switch box (Method 1). It eliminates the need to re-identify white wires as hot travelers (per NEC 404.2(A)), keeps the neutral path continuous and easy to trace, and requires exactly one spool of 14/2 and one spool of 14/3 NM-B. Buy the Leviton 5603-2W (15A, 120V, 3-way toggle) for a reliable, code-compliant baseline device.

Tools, Materials, and Device Ratings

Do not rely on cheap twist-on wire nuts for multi-wire traveler bundles. Lever nuts provide a verifiable, gas-tight connection that you can visually inspect.

Materials List

  • Switches: (2) Leviton 5603-2W 15A 3-Way Switches (or equivalent 15A rated SPDT switch).
  • Line/Load Cable: 14/2 NM-B (Romex) with ground. Rated for 15A circuits.
  • Traveler Cable: 14/3 NM-B with ground. The third conductor provides the second traveler path.
  • Breaker: 15A Single-Pole (e.g., Square D HOM115 or Eaton BR115), assuming standard 14 AWG branch circuit wiring.
  • Connectors: Wago 221-413 (3-port) and 221-412 (2-port) lever nuts.
  • Grounding: 14 AWG bare copper pigtails, cut to 6-inch lengths.

Tool List

  • Wire Strippers: Klein Tools 11055 (calibrated for 14 AWG solid copper to avoid nicking the conductor).
  • Voltage Testing: Non-contact voltage tester (Klein NCVT-2) plus a CAT III solenoid tester (Wiggy) or digital multimeter. Never rely on an NCVT alone to confirm a dead circuit.
  • Screwdrivers: #2 Robertson (square) and #2 Phillips insulated drivers.

Mains Safety Protocol (Read Before Opening the Panel)

WARNING: Lethal Voltage Present. Working inside a switch box exposes you to 120V AC mains voltage, which can cause fatal electrocution or arc flash burns.
  1. Turn off the 15A or 20A breaker feeding the circuit at the main panel.
  2. Apply a lockout/tagout device to the breaker panel if others are in the home.
  3. Test your multimeter or solenoid tester on a known live outlet first to verify the meter works.
  4. Test the target switch box: measure Line-to-Neutral, Line-to-Ground, and Neutral-to-Ground. All readings must be exactly 0.0V.
  5. Only proceed once the circuit is verified dead. Local AHJ (Authority Having Jurisdiction) codes may require a licensed electrician for new circuit pulls from the panel.

Step-by-Step Wiring: Power to Switch 1 to Switch 2 to Light

This procedure assumes the standard routing: 14/2 power enters Switch 1, 14/3 runs between Switch 1 and Switch 2, and 14/2 runs from Switch 2 to the light fixture. Strip all wire ends to exactly 5/8 inch.

  1. Bond the Grounds (Both Boxes): In both switch boxes, connect the bare copper ground wires from all entering cables together with a Wago 221-413 lever nut, adding a 6-inch 14 AWG bare pigtail. Connect the other end of the pigtail to the green ground screw on the 3-way switch. Do not skip the ground pigtail; the switch yoke must be bonded to the equipment grounding conductor.
  2. Wire Switch 1 (Line Side):
    • Identify the incoming 14/2 power cable. Connect its black (hot) wire directly to the Common terminal (the single dark-colored/black screw) on Switch 1.
    • Take the 14/3 traveler cable heading to Switch 2. Connect its black wire to one of the brass Traveler screws.
    • Connect the 14/3 red wire to the other brass Traveler screw. (Order of brass screws does not matter).
    • Wire-nut the incoming 14/2 white (neutral) wire directly to the 14/3 white wire using a Wago 221-412. This passes the neutral through the box to Switch 2. Do not connect any white wires to the switch terminals.
  3. Wire Switch 2 (Load Side):
    • Take the 14/3 traveler cable arriving from Switch 1. Connect its black wire to one brass Traveler screw, and its red wire to the other brass Traveler screw.
    • Take the 14/2 cable heading up to the light fixture. Connect its black (switched hot) wire to the Common terminal (dark/black screw) on Switch 2.
    • Wire-nut the 14/3 white wire (arriving from Sw1) to the 14/2 white wire (heading to the light). This completes the neutral path to the fixture.
  4. Terminate the Light Fixture:
    • At the ceiling box, connect the fixture's black (or ribbed/smooth hot) wire to the 14/2 black wire arriving from Switch 2.
    • Connect the fixture's white wire to the 14/2 white wire.
    • Bond the fixture ground to the box ground and 14/2 bare ground.

The Most Common Botch and Its Symptom

The single most frequent error when wiring 3-way switches is mixing up the Common terminal and the Traveler terminals. Because manufacturers do not universally standardize screw placement (the dark Common screw might be on the top, bottom, or one side depending on the brand), DIYers often assume the two screws on one side are travelers and the isolated screw is the common, which is not always true.

The Symptom: If you land the Line Hot on a brass traveler screw at Switch 1, and a traveler wire on the dark common screw, the circuit will exhibit "conditional logic" failure. The light will only turn on if Switch 1 is left in one specific position (e.g., UP). If Switch 1 is flipped DOWN, Switch 2 becomes completely dead and will not operate the light from either position.

The Fix: Turn the power back off. Look closely at the switch yoke. The Common screw is almost always a darker color (black or dark brass) and is physically isolated from the two brass traveler screws. Move the single line/load hot wire to the dark screw, and ensure the two matching traveler wires (red and black of the 14/3) are on the brass screws.

Verify and Test (Expected Meter Readings)

Before pushing the switches into the drywall boxes and installing the wall plates, perform a live verification test.

  1. Restore power at the breaker panel.
  2. Set your multimeter to AC Voltage (V~), 200V or 600V range.
  3. At the light fixture (with the bulb removed for safety), place the black probe on the socket's center brass tab (hot) and the red probe on the threaded silver shell (neutral).
  4. Expected Reading (Switches ON): 114V to 126V AC.
  5. Expected Reading (Switches OFF): 0.0V AC.
  6. Toggle Switch 1, then Switch 2, in all four possible combinations (Up/Up, Up/Down, Down/Up, Down/Down). The light must toggle on and off seamlessly regardless of the other switch's position.

NEC Code Citations and Grounding Rules

When executing this wiring method, you are adhering to several critical articles within the NFPA 70 National Electrical Code (NEC):

  • NEC 404.2(A) (Switching the Grounded Conductor): You are strictly forbidden from routing the white neutral wire through a switch terminal to break the circuit. The switch must only interrupt the ungrounded (hot) conductor. By using the 14/3 white wire solely as a pass-through neutral in this guide's routing method, you remain fully compliant without needing to re-identify the white wire with black tape.
  • NEC 250.148 (Equipment Grounding Conductor Connection): The grounding pigtails must be secured to the metal box (if applicable) and the switch's green grounding screw. Relying solely on the switch yoke mounting screws for grounding is a violation and a severe shock hazard if the switch is removed while energized.
  • NEC 314.16 (Box Fill Calculations): 3-way switch boxes often become crowded. Ensure your switch boxes are rated for the volume of wires entering them. A standard 14/3 cable counts as 4 conductors for box fill (Black, Red, White, plus the internal clamp/device allowance). Use deep 2.5-inch or 3-inch single-gang boxes (minimum 22.5 cubic inches) to prevent crushing the traveler wire insulation against the metal strap of the switch.

For further safety protocols regarding residential electrical work and arc flash prevention, refer to the OSHA Electrical Safety Guidelines. Always defer to your local electrical inspector if your municipality has adopted amendments to the baseline NEC standards.