Compact Fluorescents

I have always taken that to mean base-down, but I have several mounted in all possible positions in my home and have suffered no ill effects to date.

ditto

You guys are lucky or I'm doing something wrong. For some reason, I have had problems with attaining any life improvement for these devices over regular incandescent lamps.

I use a Sharpie marker and I write the installation date on mine so I can estimate the lifetime.

Ditto.

One thought, though - compact fluorescent lamps are often heavier than their equivalent-output incandescent lamps. On a bayonet-type electrical fitting, commonly used for lamps in the UK, the extra weight as presented to a fitting laid on its side can sometimes compress the spring of one of the two contact plungers and extend the other as the lamp hangs down from the horizontal. Now, that might be an issue, it might not - it's just something to be aware of.

Ditto. In enclosed fixtures, all angles etc.

Yeah i have them in lamps at all possible position have had no problems with them. Didn't know there was a position. Guess I'll have to read the package next time.

"Guess I'll have to read the package next time."

No, no, no. Don't do that, then you'll get all confused.

That happens any time I read them. I think they write them that way for legal reasons. Just in case something goes wrong.

I've got a few that start very slowly, and get worse with age, if mounted base-up (typical ceiling fixture). I've observed that the worst in this regard are those with two or four U-shaped or "hairpin" sections, as opposed to the spiral type. I speculate that most of the mercury winds up down at the bottom of the bend when it condenses after use, and is out of the arc path, so doesn't get energized readily when the bulb is next turned on , but that's a guess. The shallow slope in the spiral would retain more mercury AND hold it closer to the high voltage arc, easing startup. It may as well be the difference between manufacturers, how they build the ballast, etc., but I don't actually know.

Many start poorly when cold: those in my [unheated] barn are nearly useless when the temperature goes much below zero F ( -17 or -18 C). The "hairpin" ones are poor starters even up at the freezing mark, but do eventually get going, gradually brightening over ten or twenty minutes. Outdoors, I have a couple of spiral types, one base-up, and one horizontal, which are on 24/7. When temperatures plunge, they're down to a dim orange glow. I suspect that if I turned them off for more than a few minutes, I'd have to take them indoors and warm them up before I could re-start. I have not found ANY that claim to start below zero F, though I can buy electronic ballasts for conventional fluorescent tubes that state that they will work to -40.

One other observation: horizontally-mounted compact fluorescents seem to go into a flicker mode before final failure, and it happens at much less than rated lifetime. The hairpin type seem to be worse, but again, that may be due to the difference between manufacturers and their quality, rather than construction itself. This is based on a four-socket ceiling fixture in a living room. A nearby hanging unit has five CF bulbs in base-down configuration, and lifetime is noticeably better. Very few go into the flicker mode in it.

Both ends look like they could thread into something. Right way up is to have the glass part out and screw the metal part into the socket.

Hahahaha!

This web site (scroll to the bottom of the page) seems to have a theory on this topic:

"The mercury inside a compact fluorescent lamp condenses at the coldest point on the lamp. When the lamp is in base-down position, the mercury drips down near the ballast, where it revaporizes because of the higher temperatures generated by the lamp electrodes and ballast. As a result, some CFLs operating in a base-down position produce 15% to 20% less light than when installed base up. Circlines and CFLs with coiled tubes or other shapes that allow the mercury to collect away from the ballast are not as affected by position."

MRDPE

TheProfessionalEngineer.com

The life of the lamp will also be shortened if it overheats, I've designed downlights using folded compact lamps & I had to ensure that the tip of the lamp sat just outside the reflector to keep cool.

My initial response is that this is merely a legal disclaimer void of any content other than semantics. Now that I've read some of the posts about poor or otherwise influenced performance, I have to wonder. Still, SteveS had it right - the metal end is the wrong way up...

Light dimmers Can be very bad for them. Do you use one on that circuit?

"Light dimmers Can be very bad for them"

Unless they're the high frequency type designed to work with fluorescents.

I believe it is the other way around. The CFL must be designed to work with the dimmers. Most power electronic devices (like the ballasts designed into CFL) have to work with a very defined range of operating voltages, current, line frequency etc. Often times if you reduce the voltage, the device will attempt to pull more current to make up the reduction in power, or it will increase its own switching frequency to output the correct power level that the circuit expects to deliver to the bulb. That is why most dimmer switches (most use a phase controlled SCR) will destroy most CFL's in fairly short order. There are a limited number of CFL's on the market that are designed to be dimmed, and the ballast circuits are designed to recognize the reduced power input and correspondingly reduce their power output instead of trying to compensate for the lower input voltage.

Roger that, I asked a rep from Sylvania about a year ago if their CFLs could be used with rheostat dimmers. His reply was "not very well, they were working on one that should be available in a year or so". I'm thinking by summer we may see a big ad campaign...

Megaman are selling dimmable CFLs in Europe since last year some time....

Fluorescent dimmers were available when I was working in commercial lighting design some 12 years ago. Then the dimmer unit replaced the standard ballast but the lamp was not special. I imagine that the design has improved a lot since then, Apollo is one firm that makes these units.

From a former Sylvania R&D EE, theory has it that base up is the worst condition. The emitter coated coil is the concern. When the coil looses all of its emitter, the lamp is done (i.e. end of life). There are much larger concerns such as the cycling or number of starts that occur. If left on all of the time, a fluorescent lamp will generally last about twice its rated life. If turned off and on frequently, the life will be substantially shortened. The type of starter device enclosed in the base makes a big difference also. Some of them cause mustiple arc strikes and thereby cause the same damage as short cycle time. It varies between manufacturers to the point that it is difficult follow the trends. That, plus as soon as the mfg. realizes a "short life" issue exists, they go and try something different.

Most compact lamps are now coming from China which has some 4000 lamp manufacturers. They substitute quantity for quality as a solution to short life. Its a way of life....

I switched to CFL's a few years ago. Tonight I slipped across the street to pick up a sandwich and returned to the odor of burning. With 6 TV's and 10 PC's running in the shop I started checking each (with my nose). Unable to determine the source quickly, I shut down everything, then noticed a dark corner. The lamp was dark. I had to move it outside as the stench was quite nauseating. Is this common? Never seen this before.

Never seen that before either. Suggest you take it to the point of purchase.

The glass appears to have fractured at the point of entry, the question is, was there a flaw in the glass before usage at that point or is it because of the heating effects....

A question that nobody can answer, but I bet that rough handling is given as the cause and guarantee witheld!!!

I have round fluorescent bulbs mounted in cheap ceiling fixtures (30 years old, and designed for incadescent bulbs 60 watts maximum) that are base-sideways. Of the 3 base-sideways situations, two cause an irritating sound. The sound stopped in one of the 2 audible situations when I switched fluorescent light bulbs. The sound is not heard when base-up or base-down.

Solution: Use round fluorescent bulbs that emit sounds in areas where nobody cares about the sound. This assumes that efficiency of sound emitters is near the efficiency of non-sound emitters.

Can anyone comment about the efficiency of sound emitting fluorescent bulbs? If the efficiency of sound emitters is low enough, should I throw them away or use them for 1/2 hour intervals until they stop working?