Dimmer works when wired wrong... why?

[Redm 0]

Hi! I'm trying to install a Dimmer 2. I have a very simple setup up to now, but a somewhat strange behavior. Basically, when I wire the Dimmer correctly I can't turn the light off, it starts blinking. When I swap the incoming N and L, though, it seems to work fine. What's going on?

 

So the setup is: A Dimmer 2 wired according to 3-wire setup. Incoming N and L, which I verified to be N and L. And a single dimmable LED bulb connected to the load output and N. No switch up to now. Also no Bypass.

When start that setup and turn the light off (via ZWave) the light starts flickering/blinking. It looks like it's fighting between being off and the minimum brightness of 1 (Config parameter 1), back and forth. 

Now the strange thing is: If I swap the incoming N and L wires, so they are essentially "wrong" according to the diagrams, then everything works fine! Why? How can I fix it?

I tried recalibration (parameter 13), powering the device on/off, nothing changed so far.

 

Btw. if I have it "correctly" wired and connect a switch to S1 and turn it on, then everything also works as expected. I can dim to any value, switch on/off via ZWave. If I turn the switch off, I'm back to the flicker/blinking problem...

[JureZ 1]

hello. Do you not have bypass to also conect it and try? maybe there is some induced voltage on the s1? Try to disconect the s1 and just dim with app.

[Redm 0]

Well, I have the Bypass, but haven't tried it yet, to not add too many variables to the problem... 

Quote

maybe there is some induced voltage on the s1? Try to disconect the s1 and just dim with app.

Well, the initial problem description is without anything connected to S1/2/x. Just the power and the LED bulb.

[Tim__ 112]

If your load is less than 50W, then  the flickering you see is a symptom of not having a bypass. More info here:

 

 

Edited May 5, 2023 by Tim__

[Redm 0]

Ok, found some time to have a closer look over the weekend...

 

On 5/6/2023 at 12:39 AM, Tim__ said:

If your load is less than 50W, then  the flickering you see is a symptom of not having a bypass.

Don't think so. It's not really a flickering, as I indeed see it with low dimming levels. It's more a fast on/off blinking. I also installed the Bypass now, but it does not make any difference.

 

I did find however, that this is indeed somehow tied to the S1 connected from an externally switched L. Initially I wrote S1 was not connected, but I fooled myself here. S1 was indeed connected. When I actually remove the S1 cable from the Dimmer, everything works as it should.

 

However, the question remains, why the dimmer behaves strange when S1 is connected, but the external switch off. I would expect the cable at S1 to be essentially dead... Strange thing is, that doing a continuity test between the L cable at S1 (coming from the switch) and N seems to indicate a connection. Well, sort of... the tester does not give a clear continuous beep, but more a buzzing (maybe 50Hz?). 

 

Independent of the cause of the above observation, my theory would be that there is some current flowing from the L terminal to the only seemingly dead S1 terminal (or maybe from S1 to N..?). And this is somehow causing the blinking effect. If swap N and L at dimmer, then no current is flowing and everything is stable.

 

Only remaining questions is, if it is safe to run the dimmer like that?

N at L terminal

L at N terminal

L at S1 terminal via switch

LED at output terminal

[Tim__ 112]

You might have some induced voltage in your switch wire.  Try to move the switch wire away from others (especially those carrying higher currents), and any wire crossings should be done at 90 degrees.

 

I personally wouldn't swap L and N. It could be putting live voltage somewhere it shouldn't be, which is potentially a shock or fire risk.

[Redm 0]

On 5/8/2023 at 9:46 AM, Tim__ said:

You might have some induced voltage in your switch wire.  Try to move the switch wire away from others (especially those carrying higher currents), and any wire crossings should be done at 90 degrees.

Yea, that was my thought as well, after writing above post. And that was probably the cause for the blinking. I tried some measuring today, after having everything orderly installed, and now the strange blinking is gone, and also that buzzing in continuity test. 

 

So everything might be great. However, what I just noticed again, and forgot to mention initially:

I can't turn the dimmer off with the switch. I can turn it on, but not off again... (with proper wiring + S1 from switched L).

Looks like the dimmer does not notice the switch going off. It also does not report a scene change.

If measured between S1 and N (the real N) and the switch is off, my voltage tester showed ~50V... With the swapped wiring this is 0V. Not sure if that means anything...

I also tried to use some external wires trying to rule out some still possible induced voltage, but that didn't change anything. Although there were still a few centimeters of side by side wires. Not sure if that is relevant, though. And there are no high currents. That LED and the dimmer is all that is running there...

 

Pretty strange, as others seem to run "S1 from L" successfully...