To wire two lights controlled from two separate locations (commonly searched as a 2 way switch wiring diagram with 2 lights), you must run 14/2 NM-B cable from the breaker panel to the first switch, 14/3 NM-B cable between the two switches to carry the travelers, and 14/2 NM-B from the second switch to the first light fixture, daisy-chaining to the second light.

Terminology Note: In UK, AU, and IEC standards, this setup is called a 2-way switch circuit. In US NEC standards, the exact same physical device and logical function is called a 3-way switch. This guide uses the US 3-way physical layout (Common, Traveler 1, Traveler 2) as it is the global standard for modern DIY bench and jobsite searches, but the electrical logic applies universally.

⚠️ MAINS VOLTAGE WARNING: This procedure involves 120V AC line voltage. Before touching any terminal, turn off the branch circuit breaker, apply a lockout/tagout device, and verify the circuit is dead using a non-contact voltage tester (NCVT) and a multimeter. NEC-style guidance is provided here; your local Authority Having Jurisdiction (AHJ) has final authority on code compliance.

Terminal Mapping and Diagram Symbols

Before stripping any wire, you must identify the terminals on your physical switches. Standard residential switches (like the Leviton 5603 or Lutron Claro) do not use 'Line' and 'Load' markings like single-pole switches. Instead, they use a Common terminal and two Traveler terminals. The table below maps the physical device to standard schematic symbols.

Terminal Name Physical Screw Color Diagram Symbol Wire Color (NM-B) Function in Circuit
Common (COM) Black or Dark Brass C or COM Black (Line) or Red (Load) Carries unswitched hot IN (Switch 1) or switched hot OUT (Switch 2).
Traveler 1 (T1) Light Brass T1 or L1 Red (in 14/3 cable) Carries switched potential between the two switches.
Traveler 2 (T2) Light Brass T2 or L2 Black (in 14/3 cable) Carries switched potential between the two switches.
Ground (GRD) Green ⏚ or GND Bare Copper or Green Equipotential bonding path for fault current.

Reading the Diagram Symbols

When looking at a standard 2 way switch wiring diagram with 2 lights, you will see specific symbols. A solid black line represents the unswitched 'Line' (hot) conductor coming from the panel. A dashed or red line typically represents the 'Switched Hot' (load) conductor going to the fixtures. The two parallel lines connecting the switches are the 'Travelers'. In IEC diagrams, you may see 'L1' and 'L2' for travelers and 'COM' for common. In US diagrams, the travelers are often just drawn as two parallel wires without specific labeling, relying on the physical brass screw color for identification.

Node-by-Node Wiring Trace (Source to Load)

This trace follows the most common, NEC-compliant topology: Power enters at Switch 1, travelers run to Switch 2, and the load is daisy-chained from Switch 2 to Light 1, then to Light 2. We assume a 15A circuit using 14 AWG copper wire.

  1. Node 1: Panel to Switch 1 (Line In). Run 14/2 NM-B from the 15A breaker. Connect the black (hot) wire to the Common (black) screw on Switch 1. Connect the white (neutral) wire to the neutral pigtail in the switch box using a wire nut. Connect the bare ground to the green ground screw and the box ground pigtail.
  2. Node 2: Switch 1 to Switch 2 (Travelers). Run 14/3 NM-B between the two switch boxes. Connect the red wire to Traveler 1 (brass) on Switch 1, and the black wire to Traveler 2 (brass) on Switch 1. At Switch 2, connect the red wire to Traveler 1 and the black wire to Traveler 2. Note: The white wire in this 14/3 cable is not used as a neutral here; it must be capped off at both ends, or re-identified with black electrical tape and used as a traveler if preferred, though capping is standard for dead-end travelers.
  3. Node 3: Switch 2 to Light 1 (Switched Hot). Run 14/2 NM-B from Switch 2 to the first light fixture. Connect the black wire to the Common (black) screw on Switch 2. At the light fixture, connect this black wire to the brass (hot) screw on the light socket.
  4. Node 4: Light 1 to Light 2 (Daisy Chain). Run another 14/2 NM-B from Light 1 to Light 2. At Light 1, splice the incoming white neutral from Switch 2 with the white neutral going to Light 2, and the white neutral pigtail for Light 1 itself. Connect the black hot from Light 1 to the black hot going to Light 2. At Light 2, connect black to brass, white to silver.
💡 Pro Tip: Torque Matters. Most DIYers hand-tighten terminal screws until they 'feel tight'. For 14 AWG copper on standard residential switches, the manufacturer spec (e.g., Leviton) requires 0.5 in-lbs to 0.75 in-lbs of torque. Under-torquing causes high-resistance connections that arc and melt the switch housing over time. Use a calibrated torque screwdriver.

Grounding and Polarity Verification

A frequent failure point in multi-light switch loops is the degradation of the ground path or reversed polarity at the fixtures. The ground path must be continuous from the panel ground bar, through the bare copper in every cable, spliced in every box with a copper crimp or wire nut, and terminating at the green screw on both switches and the grounding screw on both light canopies. Never daisy-chain grounds by looping the wire around one screw and continuing to the next; always use a pigtail.

Polarity at the light fixtures is critical for safety. The switched hot (black) must always land on the brass screw of the socket (which connects to the center tab at the bottom of the bulb). The neutral (white) must land on the silver screw (which connects to the threaded outer shell of the bulb). If reversed, changing a bulb with the switch off still exposes the user to 120V AC if they touch the threaded shell.

Multimeter Testing and Troubleshooting

Before energizing the circuit, use a multimeter to verify your connections. Set your meter to the Continuity (beep) or Resistance (Ω) setting. Ensure the breaker is OFF.

1. Verifying the Common Terminal

If you bought a switch where the screws are all the same color (common on cheap imports), you must identify the Common terminal. Place one probe on a screw and the other probe on the two remaining screws. Toggle the switch. The screw that shows continuity with one traveler in the 'up' position, and the other traveler in the 'down' position is the Common terminal. Mark it with a silver paint pen.

2. Checking for Short Circuits

With all wires connected but the breaker OFF, place one probe on the hot bus bar (or the black wire at the panel) and the other on the neutral bus bar. The meter should read 'OL' (Open Loop) or infinite resistance. If it reads < 1 ohm, you have a dead short—likely a pinched neutral or a hot wire touching ground in one of the ceiling boxes. Do not energize.

3. Live Voltage Verification (Energized)

Once the breaker is ON, set your meter to AC Voltage (V~).
• At Switch 1 Common: Read 120V (nominal 114V-126V) to ground.
• At Switch 1 Travelers: One traveler will read 120V to ground, the other will read 0V. Flip the switch; the voltages will swap.
• At Light 1 Socket: Read 120V across the brass and silver screws when both switches are toggled to the 'ON' state. Read 0V when toggled 'OFF'.
If Light 1 works but Light 2 does not, the fault is isolated to the Node 4 daisy-chain splice. Check the wire nuts at Light 1 for a loose neutral connection, which is the most common cause of a dead downstream fixture.

For further reading on switch loop requirements and neutral conductor rules in switch boxes, refer to the NFPA 70 National Electrical Code (NEC) Article 404.2, which mandates a grounded circuit conductor (neutral) at nearly all switch locations to accommodate modern smart switches and timers. If you plan to upgrade to smart switches later, you must pull 14/3 from the panel to Switch 1 to provide that required neutral.