CFLs burning out too fast?

I write about stuff like this for a living. In a magazine for engineers.

It is only in the past year that the electronic chips that go in the base of the bulb to make them dimmable using legacy triac dimmers have been available. If a bulb has the dimmable feature, it'll be mentioned on the packaging. LED replacement bulbs need (different, but similar) special electronics, too.

Briefly the problem is that the old fashioned dimmers work by chopping off parts of every cycle of the ac voltage and the way they accomplish this depends on certain characteristics of incandescents -- characteristics that compact fluorescents and LEDs don't possess. One characteristic is the type of reisitive load they represent; another is what happens when the voltage disappears for a portion of each cycle.

It is true that both incandescents and replacements are dimmed by varying the duty cycle of the applied voltage, but the swtiching frequency in the replacements is way higher than 120 Hz -- that's part of what the electronics is about.

If a dimmer is on full, I don't see why it would affect bulb life, but if it's doing any chopping at all, I can see where it would. Putting the replacements in can fixtures? Yeah, even though they're more efficient, the new bulbs still generate heat and that has to be extracted. It's actually harder to deal with efficiency losses in non-incandescents because they don't radiate it like incandescents -- you have to get it out by conduction.

Last I knew, only National Semiconductor and NXP (Philips) were making the chips that go into the bases of replacement bulbs to make them dimmable by legacy dimmers, but there may be a couple of others in there by now. With limited supplies, the price is high, but I can imagine IKEA working a rebranding deal with Philips. they control the sales channel and they have huge volumes -- but you's still have to look for something on the package that says they're dimmable.

 

I'd take Don Tuite's word as gospel. He's an editor of Electronic Design, and you don't get more authoritative (geeky) than that. What he probably doesn't know, since he's in Redwood City, is just how "special" CFLs are in Connecticut. CPL, the local power company, subsidizes CFLs to the tune of one dollar per lamp. The smaller ones (60 watt equivalent) list for $4.99 per carton of four. Walk into Costco and you'll find them selling for $.99 per carton!

My experience with CFLs over the past five years has been mixed. The dimmable ones don't have much of a life expectancy, at least in my fixtures. They also take a while to come up to full brightness, so I turn (and leave) them on much longer than I should. I should probably go back to incandescents for this application. OTOH, I donated 10 CFLs (big spender!) to light some elevators, where they're on all the time. So far not a single failure (several months) and they pay for themselves in electricity savings every few days.

If your CFLs are dying, here's a way to make sure you get your money back:
Three Conspiracy Theories

Richard

 

CFLs are also subsidized here by ESKOM, our national utility. One CFL sells for about $1 here. We even got free CFLs in a national drive where you brought in your old incandescent bulbs and got an equivalent number of CFLs. There was some resistance from the public mostly due to the fact that the ESKOM issued CFL bulbs were only available in "cool white" instead of the preferred "warm white". People hate the "cool white" version so much that all the stores stock the "warm white". I too prefer the "warm white" color as the "cool white" makes your house look like an operating theater.

I have noticed some brands lasting very well (Osram, Eurolux) while others from Philips pops after a month or two.

I still use incandescents in my study cause the are dimmable. We did a study at the university where I work on CFLs and the effect they have on the grid.

 

I got a dimmable CFL at True Value last month, it was $12 for one bulb (and was clearly identified on the packaging). That switch is generally on full most of the time, stays on for more than 3 hours at a time when it's used, so it should last awhile.

The CFLs seem to glows true white, not yellow, which I think is a definite improvement. But the LEDs I got for Christmas lights are labeled as "cool white" but are really more of a blue/lavender color, and not visually compatible at all with the yellow-white Christmas lights I had. It's hard to find warm-white Christmas LEDs.

 

I bought a bunch of CFL bulbs for the hallway a number of years ago. They were guaranteed for 7 years. After one week, one of them burned out. I waited to see if the others would burn out, but after several months they hadn't, so I decided to send the burned out one in for the guarantee. They sent me two new bulbs. Cool, I thought. I replaced the burned out bulb. The new one lasted only one day! Eventually I got up the nerve to use the second spare bulb. It has lasted for at least of couple of years so far, as have the other ones from the initial purchase.

It was not on a dimmer. I have no dimmers in my house at all.

These were Syvania Soft White. I try to keep all light bulb warranties and receipts.

 

Mythbusters did a segment on bulbs, and in a frequent On/Off situation, CFL's last about as long as regular bulbs.

In situations where the On/Off is once a day, they last years.

It's the ballast, being so tiny, that takes a hit at every surge, and also heat reduces it's life.

I've seen in stores now CFL's that come in two parts !

My beef with China made light products are the Christmas LED bulbs. All sealed units and as soon as one burns out, the whole set or a section becomes too bright, and burns out.

Haven't had a set that has lasted more than 2 years w/o a problem - which makes paying 3x the price to save a tiny % of energy pointless.

 

If you are willing to spend more money on LED Christmas lights, take a look at these guys:

LED Christmas Lights - LED Holiday Lighting ? LED Icicle Lights, LED Light Bulbs, LED Wedding Lights, LED Stringers

Tom