Anecdote as Data: Dimmable CFL light bulbs don't quite work right yet

aj

#1 – 11:13 AM June 4, 2009

For $20 these should make you dinner.

Sorry, CFL fans, these are still not there.

inkadinka12

#2 – 11:14 AM June 4, 2009

This is the reason I am stockpiling incandescent bubls this year. I fully believe that LEDs will solve the problem eventually, but in the meantime the push toward CFL's is a going to create a lot of problems. In some stores (e.g., my local Costco) you can't even buy incandescent floods, so I'm going to make sure I have enough to make it though the years in between CFLs and low cost LEDs.

retrojoe

#3 – 11:20 AM June 4, 2009

Yes, the dimmable ones rarely work as promised. CFLs also don't like cold weather, which was a pain when I lived in Wisconsin. You also have to worry about how the circuit is wired; I tried two in a socket that was wired in series with an exhaust fan and both emitted a dim glow for about 2 seconds before going out forever. Otherwise I'm a big fan. High Kelvin or Daylight Spectrum bulbs produce much better light than their predecessors and a decent bulb lights up as fast as an incandescent.

reventlow

#4 – 11:26 AM June 4, 2009

You need a special kind of dimmer to use those. I had the same experience. Most bulbs will say the kind of dimmer they are approved with.

Also don't expect them to dim as much as normal bulbs. They will only dim slightly. If you give a cfl too little power... you will hear a loud "POP!"

retrojoe

#5 – 12:14 PM June 4, 2009

@#4> Actually it's not so much that you need a special dimmer it's that you need an old fashioned triac style dimmer as opposed to the more recent electric dimmers or the really old rheostat dimmers. These last two cut current (rather than the sine wave) to the bulbs which is what causes the bulb to go "pop".

I was working in hardware when these things took off and had many, many returns the first few years. Most were from people putting standard CFLs in dimmable circuits.

jrishel

#6 – 12:19 PM June 4, 2009

you want a cold cathode dimmable bulb. I'm using ones like this in my dimmable ceiling fans. They do take a few minutes to get up to maximum brightness when you first turn them on, but it is an effect I've come to like, rather than having full light blast my darkness adjusted eyes.

THinkaboutit

#7 – 12:26 PM June 4, 2009

How is it that my laptop made in 2001 comes with a CCFL flourescent tube is dimmable, yet they can't make a cfl dimmable? Yes you may require a new lightswitch, but that shouldn't be rocket science.

Anonymous Anonymous

#8 – 2:03 PM June 4, 2009

RETROJOE, do not wire light bulbs in series with eletric motors. Not only is it a bad idea, I suspect that is a code violation pretty much anywhere on the North American continent.

If you must have a motor on the same circuit, size them properly and wire them parallel.

jimkirk

#9 – 3:18 PM June 4, 2009

ThinkAboutIt,

Your laptop has a specially designed high frequency switching power supply mated to that one particular CCFL. That's a lot different from using a generic phase angle controlled dimmer operating at mains frequency.

I've seen dimmers available for fluorescent bulb room dimming, but even then, they have to be used with a specific wattage, and sometimes even a particular brand/model. And you can't use them for incandescent bulbs.

One difficulty is also the fact that at low light levels, a triac based dimmer is putting out lower and lower peak voltage, so for architectural dimming (down to 1% or less of full brightness), you need a power supply that can operate on 120 volts AC down to maybe 5 or 10 volts. That's a very difficult (read "expensive") design.

So while you could build a power supply that can dim a CFL and have it sense the average voltage from your triac dimmer to control it, you'd also have to have it operate over an extremely wide supply voltage, which will also fluctuate quite a bit, and make it cheap enough to be replaced when the bulb burns out.

Yes, you could make a supply that screws into your lamp, and then have a cheap CFL screw into that, but CFLs have a hard enough time fitting in to a lot of lamps in the first place, without adding an inch or more of height.

It is possible to design a dimmer that keeps the peak voltage available while dimming. I've been toying with an idea using MOSFETs to trim the AC waveform from both sides of the peak, so it would work with traditional incandescent bulbs, and would always maintain a high peak voltage for CFLs to use. Of course, the CFL ballast circuit will need to be redesigned to accommodate the altered supply waveform. Even with all that, there may be power factor issues and other aspects to be addressed.

Some LED controller ICs that claim triac dimmability are becoming available, so I'm looking to see dimmable LED lighting available soon. I bought a Cree recessed can replacement claiming triac dimability, and I was not impressed.

I'm not convinced that simply replacing traditional bulbs is the best path in the long run.

I think the future is some sort of LED, but working with the strengths of the technology. Large distributed arrays for overall lighting, five watts or so for local illumination for reading, kitchen counters and such, and of course, rainbow colors!

hallpass

#10 – 3:35 PM June 4, 2009

I have the same problem, with roughly 20 recessed lighting fixtures throughout my house. I haven't worked up the motivation to figure out how long it would take to write of the $200-or-so it would cost to make the switch to dimable CFLs. Hearing that they don't work without changing out the dimmers, I probably will wait until I have no option.

I like the LED idea. My parents replaced the 12v mini halogens aboard their 37-foot livaboard sailboat with LEDs. It cost a couple of hundred bucks. No figures on the relative efficiency, but when you rely on wind, sun and -- as a last resort -- diesel for all of your electricity, every milliamp-hour counts.

A final thought on CFL failure modes: If you ever have a brownout, turn off all of your CFLs unless you feel like replacing them.

KeithIrwin

#11 – 4:57 PM June 4, 2009

Anecdotal counter evidence. I have a half dozen dimmable CFLs in my house. They all work fine.

I'm not really sure why the commenters seem to think that LEDs will be a panacea. The biggest problems with CFLs, this problem included, stem from the AC-to-DC conversion process which has to occur. It's this process which often has trouble with dimmers. LEDs are not alternating devices. They require direct current to work effectively.

So you're still going to have many of these same problems with LED-based bulbs as long as the downward pressure on price is sufficient to cause them to use cheap AC-to-DC converters.

Personally, I've become convinced that the real long-term solution is going to be wiring homes for DC. How many AC-to-DC converters do you have in your home? Me, I've got forty or more. My TV runs on DC. My computers and their monitors. My video game systems. My battery chargers. My wife's cell phone charger. Our cable modem. The wireless router. The DVD player. The wireless phones. Even my oven is DC (and natural gas). And almost all of my light bulbs.

At this point, I have more DC devices than AC devices. More than twice as many. And each of them has their own AC-to-DC converter. Many of these converters are cheaply made, and so they aren't very efficient by more than one measure. So the logical thing to do would be to wire the house for DC as well as AC. I could have one big AC-to-DC converter which could be highly efficient and very durable. Then individual devices could just use step-down or step-up transformers. This would lower fire risk and electrocution risk because the DC voltage level could be much lower than the AC one is. It would eliminate ground loop problems. It would make most of the CFL problems go away. And it would be much more efficient in terms of energy and materials.

Jeremiah Blatz

#12 – 6:56 PM June 4, 2009

Funny, the ones we have in our ceiling fans (these: http://www.1000bulbs.com/14-to-15-Watt-Dimmable-Compact-Fluorescents/33469/) have worked just fine for ... at least a couple years now. Counter-anecdote!

chroma

#13 – 4:59 AM June 5, 2009

KEITHIRWIN: you can't change DC voltages using a transformer.

Anonymous Anonymous

#14 – 5:24 AM June 5, 2009

@keithirwin,

You nailed it! How many wall warts, losing so much power to heat, are in most peoples' homes? Never mind the ones built into devices. Most of them also output extremely low-power, on the order of 6V-9V, so the incoming 120V (60V really I guess?) is overkill.

Personally I envision a low-power 'band' running around a room, maybe just above the baseboard, with modular snap in/out access points. This would be connected to your $500 transformer coming off your circuit-breaker box. Even if the baby touches exposed parts with wet fingers, he'd just get a battery buzz.

So Tesla was right after all.

morkus

#15 – 6:06 AM June 5, 2009

On the product page you linked, it reads at the bottom:

"These bulbs are NOT for use in totally enclosed fixtures and are NOT for use on circuits with dimmers, timers or other control devices."

Anonymous Anonymous

#16 – 10:30 AM June 5, 2009

KEITHIRWIN:
> I'm not really sure why the commenters seem to
> think that LEDs will be a panacea The biggest
> problems with CFLs, this problem included, stem
> from the AC-to-DC conversion

incorrect. the biggest problem is CFLs are less durable and more sensitive. LEDs are less sensitive and burn out less. material science.

you have a good theory of going DC , but don't you think others have already thought of it (since electricity wasn't invented yesterday).
1) you don't want DC out of your socket
2) even if you do , what voltage should it be? different devices require different voltage.

Bobkat

#17 – 4:03 PM June 7, 2009

Nobody has mentioned so far that if one is using an incandescent bulb and is dimming it, you are essentially conserving power and prolonging the life of the bulb. 100W bulb dimmed to 10W will last a looooooong time. Ergo: not bad for the environment, relatively speaking.

Joel, I suspect that the frequency of bulb burnout is due to high heat from using a high-wattage bulb inside the can light more than anything else. Perhaps a using lower-wattage bulb to start with (if you aren't dimming them a whole lot) will help.

GadgetGav

#18 – 6:43 PM June 7, 2009

I've been using dimmable CF bulbs for a couple of years in my kitchen with no problems in recessed cans.

I do have problems with them in the porch lights on a timer, but I know that's because the time switch is not the correct one. I just need to get around to replacing it.

But, as others have pointed out, either the link goes to the wrong product, or you bought a bulb that is not dimmable.

Anonymous Anonymous

#19 – 3:53 PM October 2, 2009

I have installed 41 CFL 16W bulbs in the recessed lighting throughout my home. The reduction in electricity expense was fairly dramatic. However, we recently had the experience of what is known in the industry as a "glass envelope separation". The glass which covers the cfl tubes is secured with an adhesive, apparently that adhesive fails (how frequently I was not told) when it does the glass separates from the ceramic portion of the bulb, slides down the cfl tubes and continues downward until it strikes something(in our case the kitchen countertop). After some initial stonewalling at the customer service level, the manufacturer made a reasonable contact with me, the end result being a pledge to reimburse me for the 41 bulbs at 12.98 each, and to supply me with standard bulbs to replace them. They also requested that I immediately remove all of the "dimmable CFLs" from my home.
That last request speaks volumes!!!!!