Common questions about TP-Link Smart Wi-Fi Dimmer

Configuration Guide
Updated 11-22-2023 00:36:53 AM FAQ view icon34805
This Article Applies to: 

Question 1: What types of bulbs are compatible with the Smart Dimmer and what is the maximum supported load?

Answer: Bulbs can be categorized by dimming type: Incandescent/Halogen, Magnetic Low Voltage (MLV), Electronic Low-voltage (ELV), Neon/Cold Cathode (Magnetic Ballast), Fluorescent (Electronic Fluorescent Dimming Ballast), and Light Emitting Diode (LED) (Electronic LED Driver).

Our Smart Wi-Fi Dimmers are compatible with Incandescent/Halogen, Magnetic Low Voltage (MLV), LED based on TRIAC Phase Cut (Leading Edge Dimming). Please refer to the following table:

Product Model

Supported Bulb Types

Dimming Type


Dimmable LED (MLV) - 150W Max
Incandescent - 300W Max

Leading Edge Dimming / TRIAC Phase Cut




Tapo S500D(US)

Tapo S505D(US)1.6/TS25(US)1.6



Note: To verify a bulb’s supported dimming type, it is recommended to contact the manufacturer.

Refer to the following link for more information about TRIAC Dimmer & Dimming:


1. Dimming performance can significantly vary between different types of light bulbs and even between brands and models, so we cannot 100% guarantee all dimmable bulbs are compatible with our smart dimmers. Some LED bulbs, for example, require specific dimmers designed for LED technology. When using TRIAC phase-cut dimmers, it's crucial to check compatibility and ensure that the bulb and dimmer are rated to work together.

2. Not all LED bulbs are designed to be dimmable. LED bulb manufacturers typically mark bulb packaging with an icon and label it as dimmable if it has been designed for dimming. If your LED bulb flickers, pulses, buzzes or has a limited dimming range, it likely was not designed for dimming and should be replaced with another suitable model.

Question 2: What are the possible outcomes if my bulb and dimmer are not compatible?

Answer: Incompatibility between bulb drivers and smart dimmers can cause a host of problems. Seven such problems are:

  1. Flickering: The bulb may flicker or flash on and off when the dimmer is adjusted.
  2. Inconsistent dimming: The dimmer may not smoothly adjust the brightness of the bulb. Instead, the brightness levels may jump or fluctuate unpredictably when the dimmer is adjusted.
  3. Dead travel: This occurs when changing the dimmer setting produces no visible shift in the light level.
  4. Audible noise: Due to electrical interference or voltage fluctuations.
  5. Drop-out: The bulb shuts off completely as it is dimmed.
  6. Ghosting: Where light is still visible when the dimmer switch is fully off.
  7. Overheating: Incompatible dimmers can sometimes cause the bulb to overheat. This can be a fire hazard and can also significantly reduce the lifespan of the bulb.

Question 3: Why I can turn the bulb on/off via the dimmer, but cannot adjust its brightness?


1. Check the dimmer type of the bulb and its specifications to rule out incompatibility.

Our Smart Wi-Fi Dimmer is compatible with Incandescent/Halogen, Magnetic Low Voltage (MLV), and LED based on TRIAC Phase Cut (Leading Edge Dimming)While it doesn’t support lamps based on PWM (pulse width module) or ELV (electronic low voltage) dimming.

2. Ensure the wiring is correctly installed and connected as outlined in the User Guide.

3. If you have ruled out compatibility and wiring issues, it is possible that either the dimmer or the bulb itself is defective. Try testing with an Incandescent/Halogen bulb to see if the problem persists.

Question 4: Why do my bulbs flicker within a certain dimming range?

1. Poor quality or incompatible bulbs may exhibit flickering, especially when dimmed. Refer to Question 1 to check if the bulb's dimmer type is compatible with the dimmer. It may be necessary to try different bulb brands or models to find ones that work well with your dimmer.

2. If using the smart dimmer to control several bulbs in a series, it is suggested to use the bulbs of the same model, from the same brand. You could also try reducing the number of bulbs or try one bulb at a time to rule out a particular bulb.

3. Check whether the house’s main power is unstable, or if there are unstable electrical appliances on the same circuit.
4. Use the Dimming Calibration function in the app to test whether the bulb is only stable within a certain brightness range. If so, this indicates a compatibility conflict. In this case, it is suggested to only set the dimming within the supported range.

Question 5: Why do my LED bulbs make a buzzing sound within a certain dimming range?
Answer: Since TRIAC (TRIAC Phase Cut) dimmers work by changing the cyclic current sent to the LED to dim the brightness, the bulb’s electronic components can make noise during a sudden increase in current. The higher the load power, the higher the noise.

We recommend reducing the bulb power or limiting the dimming range until the noise is within an acceptable range.

Question 6: What is Dimming Calibration?

Answer: All bulbs vary, and some bulbs may switch off entirely when dimmed below certain levels. Dimming calibration allows you set the lowest brightness threshold for your bulbs to ensure the best possible dimming experience and avoid issues such as flickering, uneven dimming, or limited dimming range.

Please refer to this link for more information: What is Dimming Calibration and how it works?

Question 7: Can I use a smart bulb with my smart dimmer?

Answer: No, smart bulbs do not work with smart dimmers. Using these devices together may cause damage to the bulb or the circuit.

Our Kasa and Tapo bulbs have built-in dimming capabilities and can be controlled using the Kasa or Tapo App, or voice assistants like Amazon Alexa or Google Assistant.

You can also use a Smart Button (such as the Tapo S200B) or assign a Smart Action within the Kasa or Tapo app to achieve smart automation for the bulb.

Note: It is generally recommended to not turn off the power source of the smart bulb (e.g., lamp, fixture), otherwise its connectivity to your network will be interrupted.

For more information about Tapo and Kasa Smart Bulbs, please visit the following link:


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