Complete Lutron S-603P Switch Wiring Guide with Clear Diagrams

For proper installation of a preset 600-watt wall-mounted dimming device, begin by identifying the three terminal screws: gold (load), silver (neutral or common), and green (ground). If the existing electrical setup lacks a neutral conductor, ensure compatibility by verifying the device’s specifications–some models tolerate neutral-free hookups, while others require it.

Strip each conductor to 5/16 inch of exposed copper, then loop them clockwise around their respective terminals. Tighten screws firmly to prevent loosening; periodic torque checks (every 6-12 months) help maintain stable connectivity. Avoid using backstab connections–they weaken over time, particularly under high-load cycles.

For single-pole configurations, connect the hot input wire to the gold terminal and the output to the fixture via the same terminal. In three-way setups, pair the dimmer’s traveler terminals with those on the companion switch, ensuring color-coded wires (red and black) match consistently. Miswiring here causes erratic behavior or non-functionality.

Verify line polarity before powering on. Reverse polarity introduces flickering, humming, or even premature failure in LED or halogen bulbs. Use a non-contact voltage tester to confirm no residual current exists before handling conductors. If dimming behaves unpredictably after installation, recheck all connections against the manufacturer’s reference sheet–common errors include swapped travelers or loose grounds.

Practical Steps for Installing the S-600 Series Preset Dimmer

Before connecting any conductors, verify the circuit voltage matches the device rating of 120V–277V AC. Use a non-contact voltage tester on each wire; even capped conductors may retain charge. Secure the mounting bracket to a standard 4″ octagonal box with #8-32 screws–avoid drywall anchors as they cannot support the dimmer’s 4.5 lb weight. Label load and line wires permanently: black for line (hot), red for load (to fixture), green for ground (bonding). If your setup includes neutrals (white), cap them individually; they are not required for this model’s operation.

Wire Color	Function	Connection Point
Black (14–12 AWG)	Line input	Top screw, brass
Red (14–12 AWG)	Fixture output	Bottom screw, brass
Green (bare or insulated)	Ground bonding	Green hex screw

After securing wires, fold them neatly into the box, ensuring no insulation is pinched under the metal yoke. Test the dimmer with a 60W incandescent bulb before finalizing wallplate installation; LED compatibility varies–check manufacturer specs for minimum load (typically 10W). If flickering occurs, add a 1W dummy resistor across the fixture terminals. Replace standard toggle wallplates with a decorator-style plate to accommodate the wider cutout; recessing the dimmer 1/8″ prevents binding when toggling.

Identifying Terminal Connections on the 603P Series Dimmer

Locate the brass-colored screw first–this is the hot terminal, designated for the live wire (typically black or red in U.S. installations). Verify the wire’s voltage with a non-contact tester before handling to prevent shorts. The terminal accepts 12-14 AWG solid copper wires but rejects stranded or aluminum conductors without proper terminal adapters.

The green screw, positioned separately, is the ground terminal. Connect it to the bare copper or green-insulated ground wire of the circuit. Failure to secure this connection violates NEC 404.9(B) and creates a fire risk. For metal boxes, bond the ground wire to the switch frame and box simultaneously using a grounding pigtail.

Directly opposite the hot terminal, you’ll find the load terminal (dull silver screw). This connects to the fixture’s supply wire–usually the same color as the hot wire but carrying power *after* the switch. Confusing this with the hot terminal trips breakers or damages LED drivers. Label both wires before disconnecting to avoid mix-ups.

On three-way configurations, the traveler terminals (marked “T”) flank the load screw. These accept the red and black traveler wires from companion switches. Swap traveler positions if the switch operates backward–polarity matters here. Use wire nuts rated for 600V minimum when extending traveler wires beyond 6 inches.

Special Cases: Multi-Location and Neutral Configurations

For systems requiring neutral (common in smart upgrades), the white wire connects to the neutral terminal labeled “N” or left unmarked near the ground screw. Skip this step unless the installation explicitly calls for a neutral–unintended neutrals cause dimming malfunctions. Always cap unused neutrals with UL-listed twist-on connectors.

Dimmers with backwire holes (push-in connectors) support 12 AWG wire only. Insert stripped ends fully until a click confirms engagement; tug-test each wire to prevent loosening. Avoid using backwire holes for repeated connect/disconnect cycles–they wear and lose tension. For longevity, rely on screw terminals instead.

Check the switch’s rating plate for ampacity limits: 600W incandescent, 150W LED/CFL, or 4.5A ballast-rated loads. Exceeding these values melts insulation or triggers thermal cutoff. For higher loads, replace with a 1000W magnetic low-voltage dimmer (MLV) or derate by 20% for elevations above 3,000 feet.

After securing connections, fold wires neatly into the box, leaving 6+ inches of slack for future servicing. Tuck wires behind the switch body to avoid pinching during mounting–compressed insulation leads to arc faults. Trim excess wire to maintain compliance with NEC 314.16(B) box fill calculations.

Step-by-Step Installation for Single-Switch Setups

Cut power at the circuit breaker before handling any electrical connections. Verify the circuit is dead using a non-contact voltage tester on both terminal screws and the ground wire.

Identify the two brass-colored screws on the switch–these mark the hot (common) and load terminals. The green screw is reserved for grounding. If the existing setup lacks a ground wire, attach a pigtail from the switch’s green screw to the metal electrical box’s grounding clip or screw.

For standard single-switch installations:

• Connect the incoming live conductor (black or red) to the top brass screw.
• Attach the outgoing conductor (also black or red) to the bottom brass screw.
• Ensure the neutral conductor (white, if present) bypasses the switch entirely–it should be wire-nutted with its counterpart in the junction box.

Tighten all terminal screws until snug–torque should reach 12-15 inch-pounds. Use a torque screwdriver for precision; overtightening can strip threads or damage the switch housing.

Fold conductors neatly into the box, avoiding sharp bends or kinks. A properly seated switch should align flush with the wall plate without forcing the device backward.

Restore power and test operation. If the switch fails to toggle lights, recheck connections–most misfires stem from reversed hot/load conductors or loose screws. For three-way compatibility (not applicable here), additional traveler conductors are required.

Finalize by securing the faceplate. Use a screwdriver bit with a magnetic tip to avoid dropping screws into the wall cavity. Store the original installation manual inside the electrical box for future reference.

Configuring the Six-Button Preset Dimmer for Three-Way Applications

Identify the common terminal on the existing mechanical switch–this is typically darker or labeled “COM.” Connect this terminal to the black lead from the preset dimmer using a short jumper wire rated for 18 AWG or thicker. Ensure the screw is tightened to 12 in-lbs; overtightening risks damaging the terminals.

Attach the remaining switch wires (travelers) to the dimmer’s brass screws. Polarity doesn’t matter here–either traveler can connect to either brass terminal. For consistency, match the wire colors if possible, but confirm continuity with a multimeter set to ohms before finalizing connections. A loose traveler will cause intermittent operation.

Load and Power Integration

The dimmer’s red lead carries the controlled output–splice it directly to the fixture’s hot wire using a twist-on wire connector (minimum 20 AWG capacity). Keep the splice inside an approved junction box; exposed connections violate NEC code 314.16. For LED compatibility, verify the fixture’s wattage matches the dimmer’s 600W max rating–exceeding this triggers built-in overload protection.

Connect the red/white striped lead to the line-side power source. Use a non-contact voltage tester to confirm the circuit is dead before handling. If the dimmer replaces a two-way switch, cap the unused traveler with a wire nut and wrap it in electrical tape to prevent accidental shorts. For mixed neutral scenarios, bond the dimmer’s white lead to the neutral bus bar only–no exceptions.

Before restoring power, verify all connections with a continuity test. Activate the circuit at the breaker and observe the dimmer’s LED indicators: steady glow confirms proper installation; flickering suggests a loose traveler or incorrect load wire. Test all three-way positions–the dimmer’s preset buttons should function identically from any switch location. If one position fails, recheck the traveler connections.

For troubleshooting, note that the dimmer requires a neutral in most three-way setups. If neutrals aren’t present (e.g., older knob-and-tube wiring), the unit won’t power on–this configuration is unsupported. For delayed fade times, hold any preset button for three seconds to access the adjustable ramp rate (1–10 seconds). Default settings work for most applications, but commercial spaces may need faster transitions.