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Smart Home Forum by FIBARO Team

[Guide] - Troubleshooting flickering lights


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So, you’ve successfully installed a Dimmer 2 and can control the lamp brightness.  However, you are getting some flickering which you don’t know how to resolve. Or maybe your lamps are flashing at certain times – either with a Dimmer 2 or without.  Read on to discover how to trouble shoot this problem.


Start by wiring up the Dimmer 2 using the 3 wire diagram found in the online Dimmer 2 manual (avoid using the 2 wire version).  Create a test-bed  version if necessary, by placing the dimmer in an enclosure and wiring up to a power point.  Doing this also allows you to change the location of the device eg to a friend’s house.


Ensure the HC2 firmware is 4.110 or above; and Dimmer 2 firmware is 3.5 or above.  After any updates do a soft reconfigure of the Dimmer 2.


Double check that the bulb is a dimmable version, and that parameter 33 reports the load as dimmable (ie “0”). Try changing the brand of bulb to see if that resolves the flickering. Check in the online Dimmer 2 manual that the bulb type is supported.


Check the total power load, and install a Fibaro bypass for loads between 5W and 50W.  Don’t use Dimmer 2 for loads under 5W, which can occur with low power led bulbs.

Ensure you have used the auto-calibrate setting, and that parameter 14 reports that the calibration has been done (ie “1”).


Hopefully by stepping through the above you will solve your flickering problem.  If not, the next step is to observe when the flickering occurs:


--- All the time, but only at lower brightnesses:

Some LED bulbs may be incompatible with the Dimmer 2. Try changing the bulb brand.  Then try changing Parameter 30, load control mode: to force leading or trailing edge control.


--- At specific times, typically around sunset and late evening:

The cause may be ripple control signals interfering with the dimmer.  Some utilities in some parts of the world inject a control signal to turn street lights and off peak hot water on and off. The control signal interferes with many types of dimmers, even non-smart ones. Incandescent bulbs are somewhat immune due to their thermal delay, however the signal can wreak havoc with led drivers, causing flickering, flashing and/or strobing effects. Ceiling fans may emit a buzzing sound when the signal hits too. You are unlikely to get a resolution from your electricity provider, as this “interference” is intentional. Changing the brand of dimmer may not work either (feel free to try it). There are two possible resolutions reported to work: First, try changing parameter 38, brightness level correction, which Fibaro introduced in a software update in 2019. Otherwise, a ripple filter will be needed to remove the signal before it hits the dimmer, eg from manufacturers Cabac and Gayrad.  You will need to ascertain the frequency of the control signal from your electricity provider, and then have the correct filter installed.


--- When specific devices are switched on or used, typically containing large motors, switchmode power supplies, or nearby industrial equipment:

The cause may be electrical interference.   If these devices are on your property you can isolate the cause by methodically turning circuits and devices off. You can also try moving your test-bed to a friend’s house to see if the problem is replicated.  It’s likely that such interference would show up on other devices in the house as well, for example audio and video equipment. You should then investigate local filtering. If it's coming in on the mains, for example you live near an industrial area, then you should discuss with your electricity provider to see if the interference is above limits or not.  You may need still need a local filter in this case.


--- When a Fibaro system alarm occurs

In case of fire, flood, high CO2 etc, the relevant z-wave devices will send alarm frames.  It is possible that the system has been configured to respond to alarm frames by flashing the lamp in a regular pattern. Check Dimmer 2 parameters 40, 41, 42, 43. Other devices such as the Smart Switch can also exhibit this issue. You can check the Home Centre logs to see when the alarms occur, and correlate this with your observations.


If this guide helped you solve your flickering lights problem, click the Thankyou button below. If you discover another cause and solution that might help others, please post it below.  And finally, if this guide doesn’t help, you must have a very unusual corner case and you’ll need to get in professional assistance!

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  • 6 months later...
On 10/20/2020 at 12:00 PM, Tim__ said:

--- All the time, but only at lower brightnesses:

Some LED bulbs may be incompatible with the Dimmer 2. Try changing the bulb brand.  Then try changing Parameter 30, load control mode: to force leading or trailing edge control.


I think this was a big one for me... I tried about 7-8 different bulbs before I found one that worked as I wanted it i.e. very warm white and no flickering.

Bypass 2 sometimes helped.


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