How to Wire a Leviton 3 Way Switch Step by Step Guide

Connect the common terminal to the power source or the fixture, depending on the device’s role in the circuit. Identify this terminal first–it’s usually darker or marked with a screw distinct from the others. For most residential setups, attach the black (hot) wire from the supply here when the control is the first in the sequence. If it’s the second, link the traveler wire from the first control instead.

Secure the two traveler wires to the remaining terminals–polarity between them doesn’t matter. Use red or blue conductors for clarity, but any color pair works as long as they’re consistent throughout the setup. Twist each wire clockwise around the screw before tightening to prevent slipping, and tug lightly to confirm grip. Install insulated boots if the device sits in a metal box to avoid shorts.

Test the configuration with a non-contact voltage detector before restoring power. Verify that flipping either control toggles the load independently. If the circuit behaves erratically, check the traveler connections–mismatched or loose contacts are the most common failure points. Label wires at both locations to simplify future troubleshooting.

For dimmable loads, ensure compatibility with the device’s ratings–some models handle low-voltage LED drivers poorly. Match wire gauge to the circuit’s amperage (typically 14 AWG for 15A circuits, 12 AWG for 20A). Avoid backstab connections; they loosen over time and increase resistance, which can overheat the joint.

Ground the metal frame if present, even in plastic boxes–code requires it in most jurisdictions. Fasten the bare copper wire directly to the grounding screw or pigtail it to a grounded outlet if the box is plastic. Confirm continuity with a multimeter if the system uses a shared ground path.

Connecting a Dual-Location Control Circuit: Key Connections

Begin by identifying the common terminal on each device–marked dark green or black–since these carry the current between poles. Connect the power source’s hot conductor (typically black) to the first control’s common screw, then run a traveler wire (red or white-red stripe) to one brass terminal on the opposite unit. Repeat for the second traveler line, ensuring both cross-connections are secured to matching brass contacts. Without this symmetry, the circuit won’t toggle properly.

Terminal Arrangement and Color Codes

Brass screws always receive the traveler wires; avoid reversing them with the neutral or ground. Standard color schemes assign black for hot input, red for the first traveler, and white-red for the second–deviations can misroute current. If retrofitting older boxes, confirm insulation integrity; frayed leads risk shorts. Tighten terminal screws to 10-12 in-lbs torque; loose contacts create resistance, overheating junctions.

Cap unused neutrals with twist connectors and ground both devices to the metal box or bare copper wire–never bond them to travelers. Verify polarity before energizing: the hot wire must enter at only one common terminal. Test each position with a multimeter set to continuity mode; clicking audibly between traveler pairs confirms proper pairing. Skip this check, and you’ll troubleshoot ghost toggles later.

For circuits feeding receptacles, split the hot feed after the first common terminal using pigtails–don’t daisy-chain from traveler screws. Ballast loads (fluorescent fixtures) may flicker if travelers carry inductive current; install snubber capacitors across brass contacts if flickering persists. Label every wired box internally with its circuit ID; future repairs hinge on precise documentation.

Essential Gear for Installing a Multi-Location Circuit Controller

Start with a voltage tester–non-contact models like the Fluke 1AC-A II detect live wires without direct contact, eliminating guesswork. Confirm all conductors are dead before touching terminals, even if the breaker is off. A typical 120V residential setup requires this safety check at both fixture locations.

For precise cuts and stripping, a lineman’s pliers (e.g., Klein Journeyman) outperforms standard models. Look for insulated handles rated for 1,000V and a built-in crimping jaw. Combine this with a wire stripper offering multiple gauge settings–12 AWG (2.05mm²) to 14 AWG (1.63mm²) covers most North American applications. Avoid cheap strippers with loose tolerances; misaligned blades fray copper strands and compromise connections.

Conduit and Fastening Components

• NM-B cable clamps: Plastic or metal clamps secure cables at entry points. Use 1/2″ clamps for 12-2 or 14-2 with ground. Ensure clamps compress snugly without pinching conductors.
• Fish tape: A 25-foot steel tape simplifies pulling cables through walls. For retrofit jobs, opt for a glow-in-the-dark model to locate it in dark cavities.
• Junction box extensions: If existing boxes lack depth, add a 1/2″ extender ring to meet NEC’s 3″ minimum volume requirement for splices. Plastic versions resist corrosion better in damp areas.

Screwdrivers must match terminal screw heads precisely. A magnetic-tip Phillips #2 (e.g., Wera Kraftform) prevents slippage on brass screws, which strip easily. For grounding wires, a green grounding screw (10-32 thread) must self-tapping into metal boxes. Copper wires should be bent clockwise under screws to avoid loosening when tightened.

Labeling is critical. Use color-coded wire nuts (tan for 12 AWG, red for 14 AWG) and permanent marker sleeves to identify travelers, commons, and grounds at both ends. For long runs, a toner probe (e.g., Klein ET310) traces wires behind drywall without dismantling outlets. Store spare parts–extra grease caps for terminal screws prevent oxidation.

Advanced Testing Tools

1. Multimeter: Set to continuity mode (Ω) to verify traveler circuits aren’t shorted. A digital model with auto-ranging (e.g., Fluke 87V) detects milliamp leaks.
2. Outlet tester: After installation, a 3-light tester confirms correct polarity and grounding. Ignore “open neutral” errors–focus on “hot/ground reverse” or “no ground” flags.
3. Circuit finder: Locates the breaker controlling the line if labels are missing. Non-invasive models like the Sperry Instruments CS61200 attach to outlets without prying covers.

Step-by-Step Guide to Identifying Traveler Conductors in a Dual-Control Setup

Turn off the power at the circuit breaker before handling any wires. Use a non-contact voltage tester to confirm the circuit is dead–never rely on a single indicator. Locate both control points in the installation; one will have two brass screws (common terminal and travelers), and the other will have one brass screw (common) plus travelers. Label the cables with masking tape as you work to avoid confusion later.

Identify the common terminal first: it’s usually darker (black or copper) and positioned apart from the other screws. At the first control point, disconnect the suspected common wire and test continuity between it and the other wires using a multimeter. The traveler conductors will show no continuity with the common but will connect to each other when the toggles are in opposing positions. Repeat this at the second control point to confirm.

Visual and Tactile Markers

• Color coding: Traveler wires are often red and black, but this isn’t universal–check local codes.
• Positioning: Travelers sit on the same side of the device (typically the outer screws), while the common is isolated.
• Wire gauge: Travelers and common usually share the same gauge, while neutrals (if present) may differ.
• Sheathing: In older installations, travelers might share a cable with the common, while newer setups separate them.

Cross-test the traveler pairs by setting the multimeter to ohms. Touch one probe to a suspected traveler wire at one control point and the other probe to a wire at the second device. Toggle the control points–continuity should appear in one position but not the other. If continuity persists regardless of toggle position, the wire is not a traveler. Document each finding immediately; mix-ups can create non-functional or hazardous configurations.

Connecting a Three-Terminal Control to Common and Ground Points

Attach the black (hot) conductor from the power source directly to the dark-colored terminal marked “COM” or “Common” on the first control device. Strip 3/8″ (9.5 mm) of insulation from the wire end and insert it fully into the terminal opening, then tighten the screw to 12–15 inch-pounds torque. Verify the connection by gently tugging the wire–it must not pull free. Repeat the process for the second device’s common terminal, connecting it to the red or black traveler wire that runs between the two controls.

Ground Terminal Handling

Wire Type	Terminal Type	Strip Length	Torque Specification
Bare Copper	Green Screw	1/2″ (12.7 mm)	11–14 in-lbs
Green Insulated	Push-In Clamp	5/8″ (15.9 mm)	Not applicable–press until seated

Wrap the grounding conductor clockwise around the green grounding screw at least 270°, ensuring no bare wire is exposed beyond the terminal. For push-in models, insert the stripped end until an audible click confirms full engagement. Cross-verify that all ground terminals are interconnected if multiple devices share the same box; omit this step only if the circuit already includes a dedicated equipment-grounding busbar.

Diagnosing Errors in Multi-Location Circuit Configurations

Check the common terminal first–it’s usually darker or marked differently on the device. If both travelers attach to the same terminal, the setup will fail. Verify continuity with a multimeter between the common and each traveler screw in all positions. No reading in one position indicates a faulty connection or broken conductor inside the wall. Replace worn cabling if oxidation or fraying is visible.

Identifying Reversed Traveler Wires

Connecting the wrong conductors to the companion unit’s traveler terminals causes erratic behavior–lights flicker or only work from one point. Label each conductor at both ends before disconnecting anything. Use colored tape or markers to track which terminal each wire connects to. Swap the two travelers at one end only if miswiring is confirmed; re-test before securing the faceplate.

Inspect the grounding connection. A loose or missing ground wire can allow stray voltage, creating intermittent function or shock hazards. Ensure the bare or green wire attaches to the green screw on both devices. Test for ground continuity with the multimeter set to ohms–readings above 1 ohm suggest poor contact. Sand the wire ends if corroded and re-secure tightly.

If the circuit still doesn’t respond, compare the installation against the manufacturer’s schematic for deviations. Split-phase systems may need a neutral conductor at both locations–older setups often lack this. Upgrade to a four-wire system if code requires neutral presence. Cap unused conductors with a wire nut to prevent short circuits.