Questions on Compact Fluorescent Lamps

I remember seeing some kind of “advice” show on TV several years ago, where they said that CFLs should only be fitted in an upright position. Apparently, using them upside-down is less effective and/or damages them, or something. Anyway, I wonder what’s the deal with that? I found nothing via Google…

Also, are there any CFLs that fit and work in (smallish) lava lamps? I’m wondering what to put in my Mathmos Telstar when they ban incandescents in the EU.

I think you’re going to need some auxiliary heating device if you use a CFL in a lava lamp.

i think if governments have any sense there will not be an outright ban on incandescent bulbs. appliances and other uses can’t use CFL and other alternatives doesn’t exist yet. replacing for general illumination, that is left on for a while, may make sense.

the base of the CFL has vents to vent heat that work in an upright position.

i’ve not seen CFL that seem that would fit in lava lamps i’ve seen. you also need lots of heat for the lava to flow which CFL don’t have.

Johnpost, does upright mean glass up or threads up or either?

I’ve wondered about this and have looked closely at the packaging of several lamps and seen nothing.

A couple of times I’ve replaced dead CFLs only to find their plastic housing charred and cracked. They were well within the wattage rating for the fixture - in fact, because they weren’t tungsten lamps, they delivered the same light with much lower wattage.

I have several CFLs in my home that I use upside down that have shown no ill-effect.
My problem with CFLs is I need bulbs which can work off a dimmer switch in several rooms in my house but dimmable fluorescents are extremely expensive. And the one that I shelled out $$$ for has become much less bright over time. Actually, they all seem to, far more so than the incandescents.

Will CFLs work in lamps with three position switches? I will probably be moving into a one bedroom condo in the near future and would like to use all CFLs.

3-way CFLs are available.

Thanks; I don’t remember seeing them anywhere.

Wally world has them:

Even if you don’t get them with three different brightness, I’ve had no problems with the few I have in such lamps. They tend to have two off and two one instead of three on and one off. Only the one brightness though.

I’ve never had a problem putting the CFLs in upside down, the ones in my bathroom are like that, and I don’t remember the instructions saying anything about not using them that way.

if it says upright it may be because of vents. on those bulbs with vents i’ve seen there were holes on both the base and glass sides but the airflow inside might be better in the base down direction.

i looked at 3 different still in the package 11, 13 and 15W CFL (60W equivalent) that had no orientation instructions nor vent holes.

a 100W equivalent CFL in use does have vent holes both base and glass sides.

only thing on all units was not to use with dimmer.

It means the metal screw-in base up. This is to dissipate heat through the metal base into the metal socket of the fixture. Lamps work better (last longer) this way – both incandescents and CFL’s. For high-wattage lamps, like theatrical lighting, this is very important. For normal household incandescents, it’s true, but not nearly as critical – you probably won’t notice the shorter lifespan. For most modern CFL’s, it’s also not so important. (It was a factor in early CFL’s.)

Wait - “dissipate heat through the metal base into the metal socket” would be using conduction, not convection, and it wouldn’t matter which end was up.

I have a three-way CFL that I got at Home Depot.

Yes, the same thing will happen if you use a standard incandescent bulb in a 3-way socket. Perfectly workable.

I use CFL in cans (threads up) in my kitchen, bathroom and basement and there have been no problems, although I have not had them in there long enough to determine if they have a shorter life in that orientation, but I have not had to replace any of them in at least a year.

Thanks everyone so far!

I’m still a bit confused about the CFL issue though. To clarify, by upright I meant glass-up. By upside-down I meant screw-base up.

Bolding mine:

So, you mean lamps (generally) work best in a base-up, glass-down position? IIRC, in that old TV show they said the contrary is true - as far as (older? It’s been a few years) CFLs are concerned anyway.

Any further advice/clarification /ignorance-fighting is welcome and appreciated.

As for the lava lamp situation, I think maybe I should contact the folks at Mathmos?

My educated opinion is that CFLs last longer base-down. When mounted base-up, the heat from the tube heats up the ballast circuitry, which is already running pretty hot. Since there isn’t much space in the base, the CFL manufacturers use small electrolytic caps, which are already marginal in high-heat environments. Any additional heat load just further shortens their life.

I use CFL bulbs in various fixtures where they are base up, base down, and base sideways. No problems that I have noticed. Note, however, that CFLs vary in quality as much as incandescent bulbs, so YMMV depending on the fixture and the quality of the bulb.

I got mine at Home Depot, too. It didn’t work out so well.


I bought two of these several years ago in a glow of environmental friendly feelings. Each of them lasted about three weeks maximum.

Now I stock up on 3-way incandescants. These usually last for at least 700 hours which is way better than the CFLs.