Lights flickering at consistent times.

N

nizak

Senior Member
In the last few weeks I’ve been noticing that most all the LED lighting in my house has started flickering.

It happens between 3 and 4 PM and lasts about 10 minutes.

It’s random, the time it occurs is the same but the days are different.

I’m not always home so I’m not sure how often it’s happening.

I have recorded 3 days that I witnessed it. Two days were back to back.

The lighting is divided up between 3 15A circuits. Two are on the same leg, one on the other.

I’m not seeing any voltage fluctuations. I’m metering it as it’s occurring.

There’s a variety of different LED bulbs and LED retrofits throughout the house.

I’m in a subdivision and I’m fairly certain my house and two others share the same xfmr.

Gonna pop the meter cover and take a look at the utility connection
 
You may need an oscilloscope to actually see the problem.

LED emitters are DC. They require a driver circuit to function off of an AC supply. The simplest driver circuits are pretty much immune to line noise and voltage variation. They are also immune to the commonly used dimming waveforms. To make an LED dimmable you need a circuit that detects the dimming waveform and adjusts the driver circuit feeding the LED emitter.

Often these dimming waveform sensing output current adjusting circuits are very sensitive to electrical noise.

What _might_ be happening is that electrical noise from some piece of equipment (perhaps utility equipment, perhaps something at a neighbors house, perhaps a smart meter using powerline signaling) is causing electrical noise that confuses the LED driver and leads to flickering.

But this electrical noise is not a gross change in RMS voltage. It is hash or something that confuses zero cross timing or something similar.

A similar 'sensitive to line noise' issue happens with some digital clocks, that set their timing by counting AC zero crossings. Some of these clocks would be sensitive to line noise and run fast in some locations.

-Jonathan
 
nizak said:
Is it just going to be a “live with it” thing?
Click to expand...
No help with electrical investigation….my experience is cheap LED shell base lamps.
Replaced with a higher priced brand from a supply house and no more flicker.

The Mrs. broke a fixture lens while cleaning a few months back, replaced the fixture.
She refused to wait for the better brand, and guess what is back.
 
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