Complete Lutron 6b38 Wiring Diagram Guide for Electricians and DIYers

Begin by isolating the control unit’s low-voltage terminals–marked C and L–for incoming power. Use 18-gauge solid copper wire, stripped precisely 3/8″ to prevent shorts. Secure connections with compression terminals rated for 20A; avoid twist-on connectors as they degrade under voltage fluctuations.

The switch module’s red lead must terminate at the load’s hot terminal–no exceptions. Pair it with a dedicated 120V circuit breaker; sharing with high-draw appliances causes interference. For multi-way setups, route the purple traveler wire through conduit separators to eliminate cross-talk.

Grounding is non-negotiable. Attach the green wire to the metal junction box’s threaded grounding screw–paint removal is mandatory. In retrofit installations, bond to existing grounding wires using irreversible crimp sleeves; solder joints corrode over time.

Test continuity before energizing. Probe each connection point with a multimeter set to Ω–readings above 0.5Ω indicate loose wiring. For dimming circuits, a thermal fuse (15A) must be inserted inline with the load; bypassing this risks overheating ballasts.

Label every conductor at both ends. Use heat-shrink tubing for permanent identification–adhesive labels peel under heat. Document exact wire paths in schematics with color-coding; store a duplicate in the breaker panel.

Ventilation requirements: maintain 4″ clearance from insulation around the power module. Install a surge protector (3000J minimum) upstream of the system to guard against voltage spikes. Overhead mounting? Ensure the enclosure gasket is intact to prevent dust accumulation on terminals.

For LED compatibility, verify the driver’s forward voltage matches the system’s 10V–120V output range. Mismatches cause flickering or burnout. When integrating sensors, wire the black lead to the neutral bus–never the load side–to avoid false triggers.

Electrical Connection Guide for the 6-Series Control Module

Begin by identifying the low-voltage terminals on the backplate–marked A, B, C, and D. Connect the communication pair to A and B first; reverse polarity here will trigger a fault code but won’t damage the device. For dimming functions, link the load wires to C (dimmer output) and D (neutral). Ensure the neutral is shared across all connected modules if multiple units operate on the same circuit.

Verify the input voltage matches the module’s rating–typically 120V or 277V–before energizing. Use a multimeter to confirm line voltage at the breaker; fluctuations exceeding ±5% can cause erratic behavior or premature failure. If integrating with a three-way setup, attach the traveler wire to the C terminal; the companion switch must support low-voltage signaling for proper synchronization.

Label all wires before securing them with terminal screws. Loose connections generate heat and may trip the thermal protector; torque specifications are 0.5 Nm for low-voltage and 0.7 Nm for line-voltage terminals. For installations in metal boxes, wrap exposed wire nuts with electrical tape to prevent short circuits against grounded surfaces.

Phase configuration is critical: wire single-pole loads directly to C, but for multi-location controls, use the Y and Z terminals on the companion unit for signal continuity. Avoid daisy-chaining more than six modules in a single loop; signal degradation occurs beyond this limit, requiring a repeater or isolated network segments.

Test each connection by cycling the load through its full range. Flickering or delayed response often indicates a misrouted traveler or incorrect phase alignment. Reset the module by toggling the breaker twice if the system enters a lockout state–this clears non-persistent errors without requiring a factory reset.

For LED compatibility, confirm the load’s wattage and inrush current are within the module’s specifications (minimum 5W, maximum 500W). Some LED drivers require a bypass capacitor (0.1 µF, 250V) between C and D to eliminate high-frequency noise affecting performance.

Ground faults on D (neutral) should trigger the internal breaker, but persistent trips suggest a reversed neutral on the circuit. Isolate the circuit and retest with a known-good neutral before proceeding. In retrofit installations, check for obsolete wiring insulation–conductive striations on older Romex can cause intermittent shorts.

Document the connection sequence for future troubleshooting. Note the color-coding conventions: blue for low-voltage communication (A/B), red for load (C), white for neutral (D), and black for hot input. Keep spare wire nuts (yellow for 18-16 AWG, red for 14-12 AWG) on hand for adjustments during commissioning.

Identifying Terminal Connections for Standard Dimmer Switch Layouts

Locate the load terminal first–marked C or COM–and connect it to the fixture’s hot wire (typically black or red). For single-pole setups, attach the incoming power source (line) to the L terminal and link it to C with a short jumper if the device lacks bridging. In 3-way setups, assign T1 and T2 to traveler wires; verify polarity by testing continuity with a multimeter–travelers should show ~0Ω when toggled between positions. Neutral wires (white) bypass the switch entirely unless integrating smart modules, where they terminate at the N label.

Terminal Matrix for Quick Reference

Switch Type	Terminal	Wire Color	Action
Single-Pole	L	Black/Red (Line)	Connect incoming power
Single-Pole	C	Black/Red (Load)	Attach to fixture
3-Way	T1/T2	Yellow/Orange	Link to travelers
Smart Add-On	N	White	Neutral return

Ground screws (green) always bond to bare copper; omit only if the junction box lacks grounding. For fan control variants, C splits into C-M (motor) and C-L (light)–match labels to corresponding fixture cables. If LEDs flicker at low dim levels, insert a bypass capacitor (0.1µF) across C and N terminals.

Step-by-Step Connection Guide for Single-Pole and Multi-Location Switch Configurations

Turn off the circuit breaker controlling the lighting circuit before handling any conductors. Verify power is disabled using a non-contact voltage tester on all terminals. For a single-point control setup, identify the hot lead (typically black or red) and neutral (white). Connect the incoming power source’s hot wire to the switch’s common terminal–usually marked “COM” or darker in color. Attach the outgoing hot wire to the remaining terminal, ensuring tight screws with a torque screwdriver (12-15 in-lbs). Secure the neutral to the fixture’s neutral terminal if applicable, avoiding any loops or exposed strands.

Multi-Location Circuit Installation

In a three-point control system, two switches govern one fixture. Begin with the primary switch: link the incoming power’s hot conductor to its common terminal. Route a traveler wire (red or another distinct color) to both switches’ traveler terminals–these connections enable toggling from multiple points. The secondary switch’s common terminal connects directly to the lamp or load. Ensure all conductors entering terminal blocks are stripped precisely (5/8 inch) to prevent shorts or loose connections. Cap unused wires with wire nuts and fold them neatly into the electrical box.

Label each wire before disconnecting existing components, especially in retrofits. For split-controlled configurations, a white wire may serve as a return path–wrap it with black tape to indicate its function as a hot conductor. Verify all junctions with a multimeter: continuity between traveler terminals should register when switches align, while the common terminal should alternate between travelers and the load path. Tuck wires into the box without pinching insulation against metal edges, maintaining a 1/4-inch gap from terminals to prevent arcing.

Test each switch position systematically. In a three-point setup, flipping any switch should invert the fixture’s state. If the device fails to respond, recheck traveler connections–miswired travelers cause erratic behavior. For dimming applications, match the load type (incandescent, LED, or halogen) to the control’s specifications, adhering to minimum/maximum wattage limits. Ground all metallic components to the equipment grounding conductor (bare or green wire) for safety compliance. Secure faceplates firmly to prevent dust ingress, which can degrade contacts over time.

Document the completed installation with a photograph before closing the box. Note any deviations from standard color-coding, such as re-purposed neutrals or shared circuits. For future maintenance, mark the circuit breaker and switches accordingly. If integrating smart controls, ensure firmware compatibility with the existing network infrastructure–some models require neutral connections even for single-point setups. Re-energize the circuit only after confirming all splices are insulated and no exposed conductors remain.

Troubleshooting Voltage Irregularities in Lighting Control Units

Measure input voltage at the power feed terminals with a multimeter set to AC mode. Expected readings should fall within 110-125V for standard installations; deviations exceeding ±5V indicate potential supply-side problems. Check the main breaker panel for tripped circuits or voltage drop across bus bars–corroded connections can reduce voltage by 3-8V per affected junction. Replace oxidized wires or tighten terminal screws to restore proper current flow.

Verify transformer output at the secondary terminals if the system uses low-voltage components. For 24V transformers, output should read 23-26V under load; readings below 22V suggest overloaded circuits or faulty transformers. Disconnect all connected loads and re-test–if voltage returns to spec, calculate total wattage of connected devices and ensure it does not exceed 80% of the transformer’s rated capacity. Add a higher-rated transformer or redistribute loads if necessary.

• Inspect control module relays for sticking contacts–audible clicking without load switching indicates relay failure. Replace relays showing visible pitting or resistance over 0.5Ω.
• Test dimming performance across full range (0-100%); flickering below 30% intensity points to incorrect load type compatibility. Use incandescent-rated modules for resistive loads and electronic-rated modules for LED drivers.
• Examine neutral wires for discoloration or brittleness–high resistance neutrals can cause sporadic voltage fluctuations. Use thermal imaging to identify hotspots in junction boxes.