Are Dimmer devices inherently 'slower' than Switches

Not strictly a Room Lighting query as I think this is more a device thing, but I'm wondering what others experiences are, when they have different device types triggered by the same rule...

I have a RL instance that switches on both my stair lights and my hall lights on motion from the hall motion detector. The stair lights are LED decking type lights plugged into a Fibaro outlet whereas the hall lights are LED downlights connected to a Fibaro Dimmer 2. When I trigger the rule, the stair lights come on and there's what seems like 2 seconds before the hall lights ramp to their level. I can see from the device events that the commands are called simultaneously and the responses are relatively close together:

From the above, the Stair Lights appear to be commanded 0.07 secs after the Hall but respond 0.3 secs quicker. What I see in reality is the Hall turning on over 2 seconds later. The above is just a snippet of the chain of events which are:

  • Alarm motion triggered
  • MQTT to Pi
  • node-Red flow triggers HE virtual motion detector via maker API
  • Room Lighting instance triggered

Regardless I'm wondering if some z wave devices (dimmer vs switch or between manufacturers) are faster than others once a message is received or this is more to do with the connected load . The Z Wave mesh is fine - no ghosts, everything connected directly at 100kbps. I'm wondering whether it might be worth trying out a different model of dimmer module. I'm in the UK so choices are limited (Aeotec, Qubino, Vesternets own) and would rather not go Zigbee as I'm in a semi detached (not sure of the US term) house and the area is saturated with WiFi (I have access points occupying all non overlapping frequencies and overlap from neighbours is high)


It depends on the quality of the device basically. It does also have some connection to the lights it self as in please check that they are actually dimmable.
In my job I see this all the time and what people think is the device dimming is just the power supply failing and they damaged the dimmer and the lights.

You have a good example here. The fibaro is one of the best ones (I even use them on non smart houses standard alone I just wish they would update them to 700 z-wave). Basically the fibaro smart "learn" the load and self adjusts for this so even though it might be capable of dimming 200w if you total load is only 50 it does adjustments itself so instead of dimming from 1-200 w as 1-100% it now makes 5-50w it's 1-100%.

The reason for the 5 is because there is also a minimum dimmable range on most lights so it chops that off as well. This means it dims quickly within it correct range. But also the fibaro has options of fade time and how quickly it needs to get to X level.

So this is why.

I had issues with a support customer where there dimmers don't learn the load and they have underloaded them we have manually adjusted where possible but the max adjustment is still nowhere near and he's having the same issue as you.

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In my experience, it's a function of the connected load and the brightness level of the dimmer. At high brightness levels, the load turns on near instantaneously. At low brightness levels, at can take a couple of seconds for the load to turn on. I believe this is a function of the PWM duty cycle output by the dimmer combined with how long it takes for the LED driver to react.


Unfortunately, I don't think there's much, if anything you can do about it. Switches don't have this issue because they're effectively at 100% brightness all of the time.

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Downlights are definitely dimmable. I'm not an electrician as my day job but have worked in electrical installation on and off (qualified C&G 236, 2394, 2395 etc). I think we may have spoke an age ago on the forum regarding bulbs with internal LED driver vs the likes of Halers.

Good to hear that you find them reliable standalone. My main reason for going with dimmer modules was that in the event of a total hub failure, the lights are still operated from the retractable switches standalone (as are my curtains on shutter modules). The usable dimmable range that the Fibaro sees during calibration varies massively between loads. I seem to get a better 'range' on Philips dimmable GU10's than I do on Collingwood H2Pros. Definitely agreed regarding Z Wave 700. One reason for me considering switching the Fibaro out is that I'm sick of p**sing about with a Z Stick to ensure inclusion with no security.

Yeah I use the 'Basic Z Wave Tool' driver and manually set parameters on Fibaro. I too had to set a higher minimum as I'd find that if I dimmed to the lowest setting and turned off the lights, turning them back on the lights would not illuminate and would popcorn on as I raised the level. Altering the minimum level sorted that. I find the range and ramping pretty crap and wish we could return to the days of 230V halogen GU10's and cheap electricity. Saving the planet makes for a crap smart home experience.

One thing I did notice on the Fibaro was that disabling the Soft Start (parameter 34 to 0) increase the response time.

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