I was at a home last week where the customer showed me what happens when her she turns on her 4" LED lights. These were bulbs that were installed into existing recessed fixtures. If she turns the switch on and off several times, they usually work and stop flickering, but it was drastic.
You can see a short video we took on Elm Energy Group's Facebook page....here....
Any suggestions or comments are appreciated! She has had a number of electricians look at it and they have had no suggestions or clues as to why this was occurring. I am confident someone in this online community has experienced this and will have input. I will be eagerly awaiting some responses!
When we're going from "old" to "new" lighting technology, it's important to make sure all the components--wiring, switch, fixture, lamp (bulb)--are designed for that application.
A fixture that came with a CFL in it 10-15 years ago might not be suitable for a contemporary CFL or an LED. 10-15 years ago, nobody concerned themselves with whether or not a light bulb would work in that fixture. If the bulb had the right base, it was a foregone conclusion it would work and be just fine. Most folks--be they consumers or people within the industry--didn't know enough at the time to understand the difference, and the technology hadn't yet changed enough to matter.
Over the course of those 10-15 years, we got better at efficiency and the tech changed to reflect that. Now we know that the variances an incandescent lamp could handle are intolerable to contemporary CFLs and LEDs.
First thing, just because it's the "lowest hanging fruit", is to make sure your lamps are rated for that use.
Then, if your lamps (light bulbs) aren't performing to expectations/product specifications, check your fixture *and* your switch. Whether you're working with a fixture, a dimmer, a timer, or a photo/motion sensor, the device needs to be rated for use with the type of lamp you intend to use. If it's not rated for that use and you go ahead and use it anyway, it'll probably work but there's a good chance it won't work "right".
In the US, most retail packaging now has this info in icons as well as print. When it's spelled out, it's usually in English, Spanish and French.
If it is an A-19 type screw base, the fixture and wiring should be compatible. The reason is that with an A-19 bulb, it was possible to place perhaps a 100W bulb in the fixture.. 60W common, even with fixtures designed for CFL's, if they accepted an A-19 screw bulb, they had to design and expect an incandescent lightbulb might be inserted. To prevent over heating and fires they would have added a thermal cut-off. But with the LED's, the heat output is generally lower. If the fixture was intended only for CFL's, which generally means the ballast is separate from the bulb, then they generally use a "pin" type fixture to exclude incandescent and LED's.
Generic, snap light switches, generic silent light switches, and generic house wiring will be compatible with CFL's and LED's... if they also accepted incandescent bulbs on the circuit.
Dimmers are special case, they were often an after thought or a room accessory built into the wall. If the flickering is caused by the dimmer, it is easy to detect and switch to a compatible dimmer. Occasionally the problem can be a defective LED, but not likely in this case since it was a whole string. If the LED lights were added to circuits with some of the lower end home automation switches, that can also be the cause... as those switches sometimes do not have a neutral going to them... and they may also be looking for automation command signals coming via the power line. X-10 switches were an example. The noise from CFL's and LED's would often cause the old X-10 switches to be flaky. Those switches were dependent on the resistance load of the old incandescent light bulbs. .
The pin or socket type fixtures were manufactured by a few companies and are no longer sold retail. Fixtures are rated by wattage, not bulb type other than a special socket for a specific bulb. The wattage is about the heat generated from the bulb- wiring must conform to UL and electrical code requirements .It does not matter how old the fixture is if in good working condition the LED will work fine
So- you can use 75watt equivalent LED in a fixture designed for a 60watt incandescent. What is confusing is the equivalent wattage on the bulb box refers to the lumens output as most consumers have no clue about lumens or radiated light. The type of on-off switch is the problem today.
Note- generally all motion sensors, home automation, remote wireless switches, etc use a electronic switch (not to go into detail on SCR's or zener diodes) which do not work with both LED and CFL lighting. The switch type must be a relay which has contact switch, like a wall switch, not a electronic or diode type AC switch. In some cases a dimmable rated LED may work
I also thought that, but I tried to put a CFL in the A-19 outside fixture at my daughter/son-in-law's house (controlled by a single push button switch) and it did not work - at all. Tried it in a table lamp and it worked fine. Put an incandescent bulb in the outside fixture and it worked fine. May have been that the CFL base was not "really" A-19 measurements (i.e., could have been too short to reach the center contact in that particular fixture), or the outdoor fixture needed its center contact arm bent up a little. I didn't get into it that much as the fixture was about 12' in the air.
I've also had some flickering - especially CFLs - with outdoor fixtures operated by a digital timer. They flicker when first turned on and then when turned off (I'm assuming there is a lead/lag time with CFLs' being able to radiate light vs voltage application and maybe the type of voltage applied to the lights in this case). The LEDs I had in the fixtures previously did not flicker (but died prematurely so I replaced with CFLs).
I think the tendency is to look at lamps (light bulbs) as though they're the same if they all have the same base, in this instance an A19. Instead, consider them as three different types of technology which each use electricity differently.
Incandescent lamps use electricity to "burn" a filament to produce heat; the light is a byproduct.
CFLs produce light by using electricity to instigate a chemical recation between mercury vapor and a phosphorescent powder.
LEDs use electricity to move electrons across a semiconductor into "holes". The light which is produced is a byproduct of the interaction between the electrons and the "holes" within the diode (simple semiconductor).
We can put the same A19 base on them, but they're still going to act differently.
With the CFLs, the first 10-15 minutes of use, the chemical reaction is initiating. "Instant on" CFLs minimize the effect, but it is still observable. In cold weather, this effect can be exacerbated. This is most likely the "flickering" you're seeing when the lights are first in use.
When the circuit supplying current to the CFL is interrupted by moving the switch to the "off" position, even though there's no longer electricity instigating the chemical reaction, the chemical reaction needs a little bit of time to stop occurring. That is most likely the "flickering" you're seeing afterward.
In this same fixture for lamps with an A19 base, you've tried LEDs which prematurely expired and you've tried CFLs with less-than-optimal results.
My guess--and that's all it is, is a guess because I haven't seen your set up with my own eyes--is that the LED expired prematurely due to electrical overload. It "fried".
My suggestion: check the timer. If you can't lay your hands on product packaging or inserts which indicate the timer is specifically rated for use with CFLs and LEDs, a resonable expectation if continuing to use that timer with CFLs and LEDs would be to continue experiencing similar "issues".
If you don't want to swap out the timer, another option is to resume using incandescents. The post-ERISA halogen incandescents are rated at 1000 hours of operational time and draw approximately 65% of the wattage that the old-fashioned incandescents required to produce equivalent light output in Lumens. If you're looking to replace 60 watt pre-ERISA incandescents, look for a 40 watt halogen or thereabouts. If you're looking to replace an old-fashioned 100 watt incandescent, look for a 65 watt halogen incandescent.
"CFLs produce light by using electricity to instigate a chemical recation between mercury vapor and a phosphorescent powder."
Not a chemical reaction, if so you would see life significantly limited by the amount of chemicals that could be contained in the light bulbs. CFL's use a gas (typically argon), seeded with a very small amount of mecury (Hg). The ballast raises the voltage in the tube and results in current flowing in the gas. The electrical energy results in the electrons bumping upto a higher energy level -- temporarily. When the electron falls back to the normal natural state - a photo is emitted. In this case some UV some in the visible range. The chemistry remains the same - no change. The phosphorus coating on the envelope absorbs the UV and bumps one of its electrons into a higher state... and when it naturally drops down to the normal state... a photon is again emitted - but this time at a know wavelength in the region we want... By choosing phosphorus isotopes you can tune the color of light emitted. You can blame this on Einstein..(sort of), his Noble prize was for the explanation of the photo electric effect.
Some of the LED bulbs also produce UV first and depend on a phosphorus coating to convert the UV to the desired wavelength. And of course there are LED's that emit light directly without exciting phosphorus; however LED's that emit light directly are generally for a single wavelength, we see them as red, blue, green, yellows, etc.
LED's often work better in cool environments - because they do not depend on the current flowing through a gas. Temperature makes a big difference on how well that Ar/Hg "ignites" and begins to carry current. Ballasts used for fluorescent tubes often include a temperature rating, use below the temperature and the bulbs are very slow to turn on and they take a while before optimal light is produced.. LED's on the other hand - tend to last longer in cooler weather. The lower temperatures results in increased life for the components.
The high gas temperatures in the Ar/Hg blubs result in the very little Hg that is in the blub slowly migrating into the glass itself. As this happens one or both ends of the bulb will take on a "dark". With the vapor deposition of the Hg into the glass, the gas looses the ability to "ignite" and carry electrical current. The bulbs flicker or do not light up. As you might expect cold temperatures (below about 50F ) can also cause the bulbs a problem.
Some of the early LED bulbs were EXTREMELY sensitive to "noise" in the household power. Three or four years ago, you would routinely see warnings not to use the bulbs with dimmers, or electronic switches -- doing so would void the warranty. And yes I had some LED bulbs that had very short lives because I ignored those warnings. The failures were not caused by the emitting diode itself, but more likely to a very cheap design on the LED driver (power supply) that could not properly handle voltage transients. Fortunately the days of those bulbs have been numbered and in the last three years the poorly designed bulbs have pretty much faded from the market.
I think the comments by Maria and Dennis have some merit for my own situation. I originally used very low-priced LED bulbs from a big box store and 1 unit did not work after 1/2 hour of use. I happened to purchase a 3-pack so I replaced the non-operating unit and all seemed fine again. Both units seemed fine and continued to last for many days but I didn't trust them and took them all back. Maybe better-quality LEDs would have worked fine but would have cost significantly more. The CFLs I'm currently using (Energy Star endorsed) do seem to do their flashing operation slightly more in the Winter than Summer but not by much. I think I'll live with it for now and replace with Halogen if they fail soon.
Still doesn't explain why the CFL didn't work in my daughter's outside fixture (with just a single-pole switch) while the incandescent did.
Some of the comments here are legit. Some are not. With my flickering light issue it has been determined it was the LED bulb and not the fixture(s). I tried different bulbs and solved the problem in both an old fan and a new fan. Not all LED bulbs are created equally.
I think, Better to replace the dimmer switch if it is not recovered then once go through the connections of bulbs. At last you can change the bulb, If the change is required for that situations