Fluorescent dawn

[vakkotaur]

This weekend there was small expo at the local mall and one of the area power companies had a booth promoting compact fluorescent lights (CFL) and LED lighting. There was demonstration to show the difference in power between fluorescent and incandescent lighting using a very large "compact" (if it could still be called such) fluorescent light with an equivalent output of 500W. It took about 90 Watts to run, but that was still less that the regular 100 W bulb used in the comparison.

While the different lamp styles were interesting, what I noticed was a confirmation of what I've suspected since we switched to CFLs at home. Some lights are on as soon as the switch is flipped. Some lights have a short delay before they turn on. Some lights seem to be at full or near full brightness immediately. Some lights start out noticeably dim and slowly come up to full brightness. At first this was a bit puzzling. It wasn't a matter of age, as a couple of the older CFLs in house were the ones switching on instantly to full (or near full, it's hard to tell) brightness.

The answer is wattage. I'll use the equivalent, rather than actual, power here. The big 500W light at the demo was cold before I switched it on. It switched on instantly and was as far as I could tell at full brightness right away. The 100 W CFL was about the same. The 75 W CFLs at home seem to be fairly quick. The 60 W CFLs start out noticeably dim and take time to brighten. The 40 W equivalent globes around the bathroom mirror start out instantly, but take a minute or two to come up to full brightness.

I suspect that besides the power used, some lights might be of better quality and come on instantly. The dim start seems to be related only to power. I am curious about a 25 W or 15 W equivalent would behave, but I have no reason to get such a thing.

I've already gotten used to the slight delay in starting. The slow brightening, like an accelerated a miniature sunrise, I find I rather like, at least at times. I'm really glad I don't get hit with the full brightness of the bathroom mirror lights right away, for example.

Comments

[altivo.livejournal.com]

I've concluded that there is a temperature factor in this start up thing, too. We have a CFL out in the barn that was put there two years ago as an experiment. It comes on at near full brightness in summer, but in really cold winter temperatures it takes several minutes to gradually achieve the same luminescence.

Recessed bulbs in the kitchen ceiling behave the same way if they have been off all night, because they are nested up into an otherwise well-insulated attic crawlspace that gets chilly compared to the interior house temperature.

Bulbs installed in table lamps mostly come on at near full brightness, though I recently replaced one of those U-shaped ones in my desk lamp and the new one takes a minute to brighten up. The new one is a different color temperature as well, "warm" white as opposed to "cool".

[vakkotaur.livejournal.com]

I'm sure temperature is a factor, too, though I think we only have one recessed fixture. Our outdoor lights are still all incandescent bulbs, but they see so little use it's hardly an issue. How cold does it get in that barn? I'm a bit leery of using CFLs in outdoor or near-outdoor situations due to the temperatures they'd encounter. If that doesn't affect bulb life significantly, I could see eventually replacing some of the outdoor lights with CFLs.

Almost all of our CFLs are the spiral design. We do have a few of the U-shaped ones, and I've noticed the same power vs. startup time and brightness relation with them.

[altivo.livejournal.com]

The barn is unheated, but tends to be a few degrees above the outdoor temperature in winter and a few degrees below in summer. The bulb in question has been in place for two years now and performs normally except that it does need a warm up period when the ambient temperature drops much below freezing. We put it out there as an experiment to find out if it would work.

I had ordinary straight tube fluorescent fixtures over the rabbit cages there and they would not start at all in cold weather.

The riding arena has six mercury vapor bulbs at about 750 watts each. Those have a loooooong warm up cycle in subzero weather, but they work. We find the bulbs never burn out, but the ballast transformers do, for some reason, and since they are a part of the fixture, the whole fixture has to be replaced. I'd like a better lighting option to replace those.