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Upside down CFL urban legend?

post #1 of 11
Thread Starter 

So, I have several CFL's in fixtures that positions the bulbs upside down (think bathroom vanity light, accent lights next to garage, etc). Someone tried telling me that CFL's arn't supposed to be inverted like that, but I find that hard to believe. Any truth to that statement? Maybe that was for first gen CFL's?


And on a possibly related note, I have a Sylvania CFL flaking out on me after only 2 months of use (skittish blinking, evoking a Saw or other favorite horror movie vibe). It happens to be one that's hanging upside down.



post #2 of 11

I have them installed vertical, horizontal & inverted - no problem with any. Haven't replaced one in two years - even ones which are turned on for short periods of time.


I haven't read about any such problem either & I have read much of what is available on the net about CFLs. 

post #3 of 11

Sounds like a voltage problem. They will not work with dimmer switches ( unless you buy a special dimmable model). and with some weird fixtures. My garage door opener is not compatible.


Between home and work I have installed probably 400 in the last 5 years, upside down is not an issue.

post #4 of 11

The reason this is stated is simple science. Hot air from the tubes rise to the base which contain the ballast electronics. In reality repeated switching and dimmers (on non dimmable units) cause more failures than running the lamps base up on quality units.

post #5 of 11

I just purchased quite a few of the GE Energy Smart T2 or T3 spiral lights, because I very much liked the color output of the light (GE Daylight 6500K). I purchased mainly all  10 watts = 40 watts.  Installed these to replace normal everyday soft lights I had.  They are installed in ceiling fans & a light fixture overy my dining room table. 

All of these T2 or T3 lights are on dimmer switches (except 1).  What I have to do is push in the dimmer switch to turn lights on & I don't touch it after that.  I don't try to dimm them because it does not work. 

Is there any danger in using these on the dimmer switch or electrical problems I will run into?  Will the bulbs go out quicker than normal?

Any advice would be greatly appreciated.

post #6 of 11
Hi vwilsonfg, First of all, welcome to the Eco Huddle!

The package the CFL came in will say if it is of the type you are able to dim or not. Some are specifically designed for dimming while others are not suitable.

What happens if you misuse them I can not say but I suggest finding out as it possibly could be dangerous.

If I come across anything in my files I will add it later.
post #7 of 11
 Hi vwilsonfg, Additional information concerning the use of CFL luminaries from the site listed at the bottom of the page:

  1. Controls. CF bulbs are not compatible with several different types of lighting controls:
    • Dimmers - Using regular CF bulbs on dimmer switches will cause the bulb to fail within days or weeks. But there are dimmable CF bulbs now on the market that can be used with any conventional dimmer switch. Dimmable CF bulbs still have some performance issues including humming, color shift, stutter dimming and only partial dimming.
    • Photocells - If the photocell acts only as a switch turning the light 'on' or 'off', there should be no problem using a CF bulb. But if the photocell acts as a dimmer, gradually turning the light on in the evening or off in the morning, then the CF bulb will fail within hours or days. (See Dimmers above.)
    • Timers - If the timer is a manual clock type, acting as a simple mechanical 'on-off' switch, a CF bulb will work just fine. But if the timer is electronic, there is a 50-50% chance that the electronics of the timer will scramble the electronics of the CF bulb and cause it not to start.
    • Motion Sensors - CF bulbs work fine on motion sensors but we don't recommend that application because of the excessive 'on-off' cycles. Excessive 'on-off' cycles (more than 20 per day) shorten life by up to 15%.
    • A good web site for information about CFL lamps is
post #8 of 11
Some CFL packing indicates that using them in the 'upside down' position can decrease light output by up to 20%.  I think this is true for many if not all CFL's, because I've done side-by-side comparisons with incandescent bulbs - when upside down, there is no doubt to me that the claimed lumens of CFL's do not compete with incandescent bulbs of the same rating.  It's a major bummer.
post #9 of 11
Hi dpvwia - welcome to the Huddle!

What brands make that note? I would like to follow up on that point. 
post #10 of 11
The URL for the GE web site for CFL FAQ's - interesting & lots of good information -

One FAQ concerns this topic heading: Can I use a CFL in any position?
Yes, GE screwbase CFL bulbs can be used in any operating position unless there is text printed on the lamp or packaging that indicates a required operating position.
post #11 of 11
I have heard CFL bulbs use more energy when used sideways in a vanity light than used upright. How true is this? Tim
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