installed a caseta dimmer but my led bulbs are flickering or buzzing, did i get a bad switch?

Diagnosis

It is highly unlikely that you have a defective switch. The flickering or buzzing you are experiencing is a classic symptom of "load mismatch" or "electronic noise" caused by the interaction between the Caseta dimmer's trailing-edge dimming technology and the driver circuits inside your LED bulbs. Because LED bulbs draw significantly less power than traditional incandescent bulbs, they often fail to meet the minimum load threshold required for the switch to maintain a stable current. When the load is too low, the switch may struggle to maintain a consistent voltage, leading to rapid oscillations in power delivery that manifest as visible flickering or an audible 60Hz buzz. This is especially common when using high-efficiency bulbs or a small number of bulbs on a single circuit. To confirm this is the issue, temporarily replace the LEDs with a standard incandescent bulb; if the flickering disappears immediately, the switch is functioning perfectly and the issue lies in the bulb compatibility and load requirements.

How to Fix It

To resolve this, you need to stabilize the current and ensure the dimmer recognizes a sufficient load. While adjusting the low-end trim is the first step, the permanent hardware solution for stubborn flickering is the installation of a Lutron LUT-MLC load capacitor.

1. Adjust the Low-End Trim: Before installing hardware, press and hold the "Off" button for about 5 seconds until the LED indicator flashes. Use the "Up" and "Down" buttons to raise the minimum dimming level. This prevents the bulbs from dipping into the "unstable" voltage range where flickering usually occurs.
2. Power Down: Turn off the circuit breaker providing power to the light fixture to ensure safety.
3. Install the LUT-MLC: Take the LUT-MLC capacitor and connect it in parallel with the load. This means you connect one wire of the capacitor to the "Load" wire (typically black) coming out of the Caseta switch and the other wire to the "Neutral" wire (white) in the electrical box.
4. Secure Connections: Use wire nuts or Wago connectors to ensure a tight fit. Do not wrap the capacitor around other wires; keep it tucked neatly in the back of the junction box.
5. Restore Power: Turn the breaker back on and test the dimming range from 100% down to the lowest setting to verify the flicker is gone.

If That Didn't Work

• Verify Bulb Compatibility: Not all LEDs are dimmable. Check the bulb packaging for "Dimmable" certification. If you are using non-dimmable LEDs, they will flicker regardless of the switch used because they lack the necessary circuitry to handle voltage modulation.
• Swap Bulb Brands: Different brands use different driver architectures. If you are using budget-tier LEDs, try switching to a name-brand bulb like Philips LED or Cree. High-CRI bulbs often have more robust drivers that play better with the Caseta system.
• Check for Neutral Wire Issues: While Caseta dimmers are designed to work without a neutral wire, ensure there are no loose connections in the wire nut chain. A loose neutral in the fixture itself can cause "ghosting" or flickering.
• Test with a Different Dimmer Model: If you are using a Caseta PD-6WCL (the standard dimmer) on a very specialized load, try the PD-10PDF if you are controlling high-wattage LED strips or electronic transformers, as it handles higher loads differently.

Heads Up

• Avoid Mixing Brands: Never mix different brands or models of LED bulbs on the same circuit. Even if they look identical, different driver timings can cause one bulb to flicker while another stays steady.
• Don't Overstuff Boxes: The LUT-MLC adds bulk to the electrical box. Be careful not to pinch wires when pushing the switch back into the wall, as this can cause a short circuit.
• Check the Total Wattage: Ensure you aren't exceeding the maximum rated load for the switch (typically 150W for LEDs), as overloading the switch can cause it to overheat and shut down.
• Firmware Updates: If you have a Lutron Caseta Smart Bridge, check the app for any available firmware updates for your switches, as Lutron occasionally releases stability patches for dimming curves.