If you are searching for a Leviton 2 way switch wiring diagram, you are likely navigating a regional terminology gap. In the UK, Australia, and Europe, a switch setup that controls a single light fixture from two different locations is called a "2-way" circuit. In North America, the National Electrical Code (NEC) and manufacturers like Leviton call this exact same configuration a 3-way switch. Leviton does not manufacture a product labeled "2-way" for this application; instead, the industry standard is the Leviton Decora 5603 (or the toggle equivalent, 5243), which is sold as a 3-way AC quiet switch.

This guide cuts through the terminology confusion. Below is the exact terminal mapping, a node-by-node current trace from the breaker to the load, and the multimeter verification steps required to wire a Leviton Decora 5603 pair safely on a standard 120V AC, 15A or 20A branch circuit.

Leviton Terminal Mapping and Diagram Symbols

Before stripping any wire, you must understand the physical terminals on the Leviton Decora 5603 and how they translate to standard schematic symbols. In electrical diagrams, a 2-way/3-way switch is represented as a Single Pole Double Throw (SPDT) switch. The single "pole" is the common terminal (the pivot point), and the two "throws" are the traveler terminals. The schematic symbol looks like a single line hitting a dot, with two diagonal lines branching off the other side.

Here is the exact terminal specification sheet for the Leviton 5603. Keep this table on your bench while wiring.

Terminal Name Screw Color Physical Location on Leviton 5603 Standard US NEC Wire Color Function in Circuit
Common (Line/Load) Black (or Dark Brass) Bottom right or top left (varies by year, always marked 'BK' or isolated) Black (Hot) or Black (Switched Hot) Receives source voltage OR sends voltage to the load. Never connects to a traveler.
Traveler 1 Light Brass Top right Red (or Black with red tape) Carries current between switches in one toggle position.
Traveler 2 Light Brass Bottom left Black, White with black tape, or Blue Carries current between switches in the opposite toggle position.
Equipment Ground Green Bottom center, recessed Bare Copper or Green Provides a low-impedance fault path back to the panel. Mandatory for metal boxes and faceplates.
Callout Tip: The Neutral Trap
Notice that White (Neutral) is missing from the switch terminal table. A standard mechanical Leviton 5603 does not use a neutral wire. The neutral bypasses the switches entirely and runs straight to the light fixture. Connecting a neutral to a brass traveler terminal will create a direct dead short the moment the switch is toggled, tripping the breaker instantly and potentially destroying the switch contacts.

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

To wire this correctly, you must trace the ungrounded (hot), grounded (neutral), and equipment grounding (ground) conductors as distinct, unbroken paths. This trace assumes a standard "Line to Switch 1, Load from Switch 2" topology using 14/2 NM-B and 14/3 NM-B cable on a 15A breaker.

1. The Ungrounded (Hot) Path

  1. Panel to Switch 1: The 120V AC Black (hot) wire leaves the 15A breaker and enters Switch Box 1. It terminates on the Black (Common) terminal of Leviton Switch 1.
  2. Switch 1 to Switch 2 (Travelers): Two wires (typically Red and Black from a 14/3 cable) connect to the two Brass (Traveler) terminals on Switch 1. These run through the wall cavity to Switch Box 2, where they terminate on the two Brass (Traveler) terminals of Switch 2. The order of the two brass wires does not matter; they are interchangeable.
  3. Switch 2 to Load: The White wire from the 14/3 cable (which must be re-identified with black electrical tape at both ends to indicate it is hot, per NEC 200.7) connects to the Black (Common) terminal of Switch 2. This wire runs to the light fixture and connects to the fixture's black (hot) lead.

2. The Grounded (Neutral) Path

The White neutral wire from the panel enters Switch Box 1. It does not land on the switch. It is spliced (using a wire nut or Wago lever connector) to the White neutral wire of the 14/3 cable. That 14/3 White wire travels to Switch Box 2, where it is again spliced straight through to the White neutral wire running up to the light fixture. The neutral path is continuous and never broken by a switch.

3. The Equipment Grounding Conductor (EGC) Path

The bare copper ground wire from the panel enters Switch Box 1. If the box is metal, a pigtail must bond the bare wire to the box itself using a green grounding screw. A second pigtail connects the bundle to the Green terminal on Leviton Switch 1. This ground path continues via the bare wire in the 14/3 cable to Switch Box 2, bonding to the metal box (if applicable), pigtailing to the Green terminal on Switch 2, and finally continuing up to the light fixture canopy to bond to the fixture's green or bare ground wire. For more on grounding and bonding requirements, refer to the NFPA 70 National Electrical Code Article 250.

Multimeter Verification and Installation Steps

Never rely on visual wire colors alone, especially in older homes where previous DIYers may have used incorrect cable types. Use a digital multimeter (DMM) to verify the circuit before making final terminations.

SAFETY WARNING: Mains Voltage
De-energize the circuit at the main breaker panel before touching any bare wire. Lock out or tag the breaker. Verify the circuit is dead using a non-contact voltage tester (NCVT) and a DMM set to AC Voltage, testing between the suspected hot and a known ground. Local codes may require this work to be performed by a licensed electrician.

Step 1: Bench-Test the Leviton Switches (Continuity)

Before installing, verify the internal mechanics of the Leviton 5603.

  1. Set your DMM to Continuity mode (the diode/beep symbol).
  2. Place one probe on the Black (Common) terminal and the other on the top Brass (Traveler) terminal.
  3. Flip the toggle. The meter should beep in one position and read 'OL' (open loop) in the other.
  4. Move the second probe to the bottom Brass terminal. The meter should now beep in the opposite toggle position. This confirms the SPDT internal routing is functional.

Step 2: Identify the Line Hot (Live Test)

With the switches removed and wires separated (safely spaced apart), turn the breaker ON.

  1. Set DMM to AC Voltage (200V range or higher).
  2. Place the black probe on the bare ground wire bundle.
  3. Touch the red probe to the exposed copper of the incoming Black wires in Box 1. The wire that reads ~120V (typically 114V-126V) is your Line Hot. Mark it with tape. Turn the breaker OFF again.

Step 3: Terminate and Torque

  1. Strip exactly 5/8 inch (16mm) of insulation from your 14 AWG solid copper wires, using the strip gauge molded into the back of the Leviton device.
  2. Insert the wires into the back-wire clamps or loop them clockwise around the side terminal screws.
  3. Torque the terminal screws to 14 in-lbs. Leviton specifies this torque to prevent the "hot-spot" heating that causes Decora switches to melt or fail prematurely under continuous 12A+ loads. If you do not have an inch-pound torque screwdriver, tighten until the screw stops, then give it a firm 1/8th turn—do not overtighten to the point of stripping the brass threads.

Polarity, Code Caveats, and Smart Switch Upgrades

When wiring any Leviton 2 way (3-way) circuit, polarity is paramount. NEC Article 404.2 explicitly requires that switches must only break the ungrounded (hot) conductor. You must never wire a switch to interrupt the neutral white wire while leaving the black wire constantly hot. Doing so leaves the light fixture energized at 120V even when the bulb is off, creating a severe shock hazard for anyone changing the bulb.

Upgrading to Smart Switches: If your ultimate goal is to replace these mechanical Leviton 5603 switches with smart switches (like the Leviton Decora Smart Wi-Fi 3-Way), the wiring topology changes. Smart switches require a neutral wire to power their internal Wi-Fi radios. If your switch boxes do not have a neutral wire bundled in the back (common in pre-1980s homes using 14/2 cable for travelers), you cannot install standard smart switches without pulling new cable or using specialized "no-neutral" smart switches that leak a small trickle of current through the load. Always verify the presence of a neutral bundle in the back of the box before purchasing smart home hardware.

By strictly following the terminal mapping table and verifying the SPDT routing with your multimeter, you ensure a safe, code-compliant installation that will operate reliably for decades. For further reading on device installation standards, consult the Leviton technical support documentation for the specific spec sheet of your device model.