Weird issue with LED lighting that I managed to fix but still not sure what the issue was

C

clemver

Member
Location
PA
Occupation
Electrician
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Was doing a kitchen remodel, all new wiring. All dimmers were lutron caseta diva dimmers. Installed and powered up dimmer 1 for the recessed lights 1st, (12) wafer LEDs. Everything with those was working perfectly fine for a few weeks while I waited for the tape light.

Installed and powered up tape light 1, everything was fine.

Installed and powered up tape light 2.

Then the ceiling lights started strobing. At 100% it was noticeable but not severe. At 50% it was straight up strobe lighting.

When I had only 1 tape light section lit, didnt matter wich one, ceiling lights were fine. As soon as I had both tape lights on at the same time as the ceiling lights, ceiling would strobe. Other than the constant power that jumped from box to box they were not connected in any way.

Each tape light dimmer controlled its own 24v dimmable power supply. At no point did I have issues with the tape light or dimming them, only the ceiling lights.

Since the caseta dimmers dont use a nuetral, I swapped out the recessed lighting dimmer with a standard diva dimmer with a neutral connection and everything was fine. I've heard that dimmers that require a neutral can fix weird issues with lighting but I dont know or understand enough about interference or backfeed to know what the actual issue was. Any insight would be appreciated.
 
clemver said:
Since the caseta dimmers dont use a nuetral, I swapped out the recessed lighting dimmer with a standard diva dimmer with a neutral connection and everything was fine. I've heard that dimmers that require a neutral can fix weird issues with lighting but I dont know or understand enough about interference or backfeed to know what the actual issue was. Any insight would be appreciated.
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Standard Diva dimmers don't have a neutral connection either. Only the ELV or Reverse Phase versions. Lutron does offer a Caseta Diva dimmer with neutral connection. DVRF-5NE.
 
Deltaforce said:
Dimmers get distorted power with other leds operate in no neutral setup
Dimmers get clean power in with neutral setup
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Yes, I think the issue relates to powering the control circuitry within the dimmer. Without a neutral, the control circuitry must be powered by whatever voltage drop is across the dimmer and the current available at each dimmer setting. Both of these vary over a wide extent as the dimmer is adjusted over its range, with low available current at low settings, and low available average voltage drop at high settings. And so without both neutral and line voltage to provide relatively clean power for detecting AC zero crossings and other control functions, it will likely be more susceptible to conducted interference.

I think what might be happening when you added a second low voltage dimmer is the following: The switching supplies in the two drivers could be operating at two frequencies which are close but are still different from each other. That could result in a "beat note" in the interference they produce that is related to the difference between their two frequencies, which could trigger the more vulnerable Caseta Dimmers into a strobing behavior. This is speculation on my part, but it's similar to other behavior I've seen that was caused by interference during the design and operation of electronic equipment.
 
Deltaforce said:
OK Neutral case, distortion within limit
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Would this be because the ground could have other paths back to transformer atleast before the label—- why would a ground vs neutral make a difference if the ground has no paths back to source expect at the panel were they all tie together ( nuetral and ground)..
 
AC\DC said:
Would this be because the ground could have other paths back to transformer atleast before the label—- why would a ground vs neutral make a difference if the ground has no paths back to source expect at the panel were they all tie together ( nuetral and ground)..
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The clue, how dimmer circuit powered.
In no neutral case, power leaked off from current into led load rich in harmonics
In neutral case power taken across supply, poor in harmonics
 
curt swartz said:
Standard Diva dimmers don't have a neutral connection either. Only the ELV or Reverse Phase versions. Lutron does offer a Caseta Diva dimmer with neutral connection. DVRF-5NE.
Click to expand...
Honestly dont even know where I got the Diva with neutral, it was "new" unused, but might have been a slightly older style. Wasn't the new LED+ with the plastic packaging, it was in a box, but it was definitely LED rated. And the one I used specifically says it needs to be wired at the load switch in a 3way setup which I thought was weird.
 
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