Why do 120 vac home LED light bulbs flicker?

[gary350]

Bedroom #3 ceiling light fixture has 2 bulbs. After being on about 30 minutes they start to flicker. Both bulbs are 1100 Lumens and they don't flicker at the same time. They appear to go from 1100 to 900 lumens then 5 minutes later back to 1100. I checked wire nuts for back connection light still flicker. I swapped old bulbs for new 1500 lumens bulbs after 45 minutes they flicker, they appear to be 1500 lumen then 1300 lumen then 1500 again.

I learned to only have 1 bulb in each fixture and flicker rate changes, 1500 lumens to 1300 lumens then 5 minutes later back to 1500 lumens.

I thought it was a heat problem then I notice every time electric clothes dryer comes on some living room bulbs flicker but on other lights flicker. Living room bulb is 20 feet from clothes dryer it always flickers when the dryer comes on. When electric heat comes, living room and bedroom light flickers. When microwave comes on none of the kitchen lights flicker.

Relatives said there LED bulbs flicker also. Flicker is not noticed when TV is on because TV does more flicker than the LED bulbs.

I know sudden power surge can make the old incandescent bulbs have lumen dips.

LED bulbs seem to talk to each other 5 bulb bathroom fixture the bulbs take turns flickering. LOL

What else is going on that I don't know about?

 

[Lightium]

Sounds strange. You may need an electrician to test your electrical grounds/wiring and your power needs.

 

[alec_t]

How are you measuring the lumens?

 

[gary350]

How are you measuring the lumens?

Photograph light meter shows brightness dropped a little for a while then gets bright again. I tested 10 light bulbs they all flicker but 1, it did not flicker for several days, then it did.

When I turn the light on bulbs do not flicker for an hours or more then flicker becomes a regular rate.

I removed glass light fixture cover so I can see which 1 of the 2 blubs flicker. With cover removed flicker rate becomes slower. Remove 1 bulb and a single bulb flickers very slow. I found 1 bulb in the group of 10 that seldom flickers it has to be on all day to flicker.

From what I see it seems to me the circuit must be turning off a few of the LEDs when the bulb become too hotter.

I have 1 bulb that is about 2 years old after being on for about 30 minutes it turns completely off. After being off for a while the bulb comes on again. I put this bulb in the spare bathroom for people that are too lazy to turn the light off.

 

[sagor1]

Have you tried different brands of bulbs? Also, some LED bulbs are labelled to not be used in fully enclosed fixtures (due to heat problems). Check your bulbs' fine print on the bulbs themselves. It could be you have a bad batch (or make) of bulbs
Can you check your AC voltage with a scope or something? Maybe there is an intermittent connection somewhere in the house wiring, which could show up as dips or spikes in the line voltage. An intermittent in house wiring could cause a fire eventually.

 

[schmitt trigger]

Maybe there is an intermittent connection somewhere in the house wiring, which could show up as dips or spikes in the line voltage. An intermittent in house wiring could cause a fire eventually.

That would also be my main concern. The lights flickering may indicate a poor connection somewhere, which eventually will overheat and could lead to a fire.

 

[gary350]

That would also be my main concern. The lights flickering may indicate a poor connection somewhere, which eventually will overheat and could lead to a fire.

I know a loose wire can arc over heat and start a fire that is why I became interested in learning what is causing all the light bulb flicker. I checked wire nuts in light fixture and wire nuts in the attic. I bought several new bulbs to see if they all flicker also. I know a sudden power surge happens when electric motor comes on, washing machine, clothes dryer, dish washer, microwave oven. Hot water heater will make a power surge too. If I had a circuit drawing of these home LED bulbs that might be helpful. The 1500 Lumen bulbs are 14W 120V = .116 amps. I have 2 amp clamps lowest setting is 1a to 6a on each meter. 0 the meter needle and wait for the blub to power down 7% amp clamp needle does not move. When I turn light switch off on a few times amp clamp needle does not move.

Amp clamp needle reads 0 and photographic light meter shows about 7% drop in lumens when bulb flickers.

The BIG bulb flicker is our 240v 40a electric central heat system coming on.

.

 

[Nigel Goodwin]

The BIG bulb flicker is our 240v 40a electric central heat system coming on.

A sudden almost 10kw load is going to make your lights flicker, assuming they are non-regulated ones (so can be dimmed using an old style lamp dimmer - to some extent). Simple ohms law, a massive load increase will cause higher voltage drop across the wiring.

In my bedroom I have an old double spot-light fitting, fed from an incandescent dimmer - and I replaced the bulbs with dimmable (simple) LED ones - and to be fair, I should have picked lower wattage LED bulbs, I picked small, but should have picked smaller. So the dimmer is always set fairly low. When the electric shower is turned on (and it's the smallest wattage shower they make), the bedroom lights SERIOUSLY dim as the mains voltage drops.

Most of the rest of the house is lit by mainly Philips Hue bulbs, along with Philips Hue light controls and Alexa voice control - none of those flicker or dim, as the dimming is done internally by PWM.

Fitting better quality, regulated and non-dimmable bulbs, will stop the flickering. If you can get Philips Hue? in the US, I can recommend them - expensive, but good quality.

 

[MrAl]

Bedroom #3 ceiling light fixture has 2 bulbs. After being on about 30 minutes they start to flicker. Both bulbs are 1100 Lumens and they don't flicker at the same time. They appear to go from 1100 to 900 lumens then 5 minutes later back to 1100. I checked wire nuts for back connection light still flicker. I swapped old bulbs for new 1500 lumens bulbs after 45 minutes they flicker, they appear to be 1500 lumen then 1300 lumen then 1500 again.

I learned to only have 1 bulb in each fixture and flicker rate changes, 1500 lumens to 1300 lumens then 5 minutes later back to 1500 lumens.

I thought it was a heat problem then I notice every time electric clothes dryer comes on some living room bulbs flicker but on other lights flicker. Living room bulb is 20 feet from clothes dryer it always flickers when the dryer comes on. When electric heat comes, living room and bedroom light flickers. When microwave comes on none of the kitchen lights flicker.

Relatives said there LED bulbs flicker also. Flicker is not noticed when TV is on because TV does more flicker than the LED bulbs.

I know sudden power surge can make the old incandescent bulbs have lumen dips.

LED bulbs seem to talk to each other 5 bulb bathroom fixture the bulbs take turns flickering. LOL

What else is going on that I don't know about?

Hello,

Some of the bulbs I have will flicker when the power line voltage varies up and down. Some other bulbs do not flicker even when the line changes up and down a bit. That tells me that there are at least two different types of bulbs, those that need a constant voltage and those that can put up with some fluctuations in voltage.
I am not sure how to buy a bulb that does not flicker with voltage changes. The ones I bought I had no idea, I just needed bulbs and got some that do not flicker.
It must depend on how well they did the design.

 

[Nigel Goodwin]

Hello,

Some of the bulbs I have will flicker when the power line voltage varies up and down. Some other bulbs do not flicker even when the line changes up and down a bit. That tells me that there are at least two different types of bulbs, those that need a constant voltage and those that can put up with some fluctuations in voltage.
I am not sure how to buy a bulb that does not flicker with voltage changes. The ones I bought I had no idea, I just needed bulbs and got some that do not flicker.
It must depend on how well they did the design.

Not really, the main issue is if they are dimmable or not - dimmable ones will vary with voltage fluctuations - it's how dimming works. Non-dimmable ones are usually regulated (switch-mode driver IC), so can't be dimmed because the regulation compensates for any voltage fluctuations.

So dimmable ones are often very crude and simple, and allows them to be dimmed, but allows them to flicker with voltage changes.

 

[MrAl]

Not really, the main issue is if they are dimmable or not - dimmable ones will vary with voltage fluctuations - it's how dimming works. Non-dimmable ones are usually regulated (switch-mode driver IC), so can't be dimmed because the regulation compensates for any voltage fluctuations.

So dimmable ones are often very crude and simple, and allows them to be dimmed, but allows them to flicker with voltage changes.

Oh that's interesting.

I never buy dimmable LED bulbs though. I don't need that function.

 

[Nigel Goodwin]

Oh that's interesting.

I never buy dimmable LED bulbs though. I don't need that function.

It depends how cheap they are as well, they could be dimmable and it not be mentioned - do they specifically state 'non-dimmable'? - and do they flicker, that's a give away.

 

[zahwi]

It must depend on how well they did the design.

That is right, all LED lights designed to work on 100-240V and the designers cut corners. If you increase the voltage to 200V the flicker will stop.

 

[gary350]

This morning I notice the 1400w space heater next to my desk came ON and the ceiling LED light got dimmer. When space heater thermostat clicked off heater light light went off and the ceiling LED light got brighter. So I turned the thermostat knob on off on off on off the ceiling LED light got dim bright dim bright dim bright. If I could still hear I probably would have heard the thermostat clicking each time light flickered.

 

[Nigel Goodwin]

This morning I notice the 1400w space heater next to my desk came ON and the ceiling LED light got dimmer. When space heater thermostat clicked off heater light light went off and the ceiling LED light got brighter.

As I've said, they are varying in brightness due to drops in the mains voltage due to changes in load, if you don't need dimming, then replace them with regulated non-dimmable LED bulbs.

 

[schmitt trigger]

It would add a lot of value to this thread that you would use a DMM to monitor the line voltage when the space heater turns on and off.
If it has the min-max function, then it is much more useful.
Without actual voltage readings, everything is anecdotal.
What I am driving to, and others have already mentioned it, is that you may have a wiring issue, that could potentially become dangerous.

 

[MrAl]

It depends how cheap they are as well, they could be dimmable and it not be mentioned - do they specifically state 'non-dimmable'? - and do they flicker, that's a give away.

All the ones I have purchased in the past say "non dimmable" as they are usually cheaper and I don't need dimming at all.
Also, for the ones that do dim with voltage, I don't know what the range is I never tested it but maybe I should just to see what they work down to in voltage. Might be interesting. That's not to say that they would work with a store bought lamp dimmer though, which would be different than say a variac test.

When they say "non dimmable" I think they mean with a store bought lamp dimmer either on a lamp or on the wall. Those usually use triacs for handling the power, and it switches on and off so the voltage is not steady. When the voltage goes lower due to another local load, the wave is still pretty much a pure sine wave. There could be a little flat topping too though, but it's continuous not repeatedly on and off.

 

[MrAl]

That is right, all LED lights designed to work on 100-240V and the designers cut corners. If you increase the voltage to 200V the flicker will stop.

We have 120vac so that's the highest I would go with any test.
The bulbs are cheaper that's probably what it is. It's funny though some do not dim at all. The ones that do dim are very annoying.

 

[MrAl]

It would add a lot of value to this thread that you would use a DMM to monitor the line voltage when the space heater turns on and off.
If it has the min-max function, then it is much more useful.
Without actual voltage readings, everything is anecdotal.
What I am driving to, and others have already mentioned it, is that you may have a wiring issue, that could potentially become dangerous.

Yeah I agree with that. For my use with my bulbs, I know for a fact that the line voltage drops repeatedly especially during the summer months. I continuously monitor the voltage with a meter and can see if it goes down.