Dimming Compact Fluorescent Lamps

[markimhoff]

Trying to dim Sylvania Compact fluorescent floods which are marked dimmable. Sylvania sent a list of recommended Lutron dimmers but Lutron customer service told me that they havn't tested any Sylvania lamps on their dimmers and don't warrant dimmers used with that product. When I used Lutron or P&S dimmers the lamps always flicker or go out. Any suggestions?

 

[kwired]

do not use CFL for dimming applications - (just my suggestion)

 

[cadpoint]

do not use CFL for dimming applications - (just my suggestion)

Excatly, I could only think I'd look up both the Ballast and the Lamp...

 

[gar]

100322-2233 EST

You will not get much dimming range with a dimmable CFL and phase shift dimming for which these are designed. Figure maybe 40% of maximum brightness. Use standard tungsten filament incandescent bulbs, and you may be able to get to 5% for a minimum.

A fluorescent fixture with a dimming ballast should give much better range than the CFLs. I have not tested one, but these provide constant filament excitation which the CFLs do not.

.

 

[markimhoff]

Trying to dim Sylvania Compact fluorescent floods which are marked dimmable. Sylvania sent a list of recommended Lutron dimmers but Lutron customer service told me that they havn't tested any Sylvania lamps on their dimmers and don't warrant dimmers used with that product. When I used Lutron or P&S dimmers the lamps always flicker or go out. Any suggestions?

Homeowner bought the lamps at a big box store and then made it my problem to make them work. Never again , live & learn.

 

[gar]

100323-0848 EST

markimhoff:

As I previously said so called dimmable CFLs have very limited dimming range.

However, a good dimmer for these or incandescent lamps is the Lutron SF-10P. This an overpriced dimmer but has the advantage that it requires (or uses) full input 120 V supply voltage to power the electronics in the dimmer. My description of this would be a "three wire" dimmer. But Lutron does not not know what I mean by that terminology. What I mean is that hot and neutral must both be supplied as input to the dimmer and the third wire is the dimmed output. This is in contrast of what I call a "two wire" dimmer where power to the electronics in the dimmer is supplied thru the load.

This SF-10P works at any dimmer position with or without any load. This is possible because both neutral and hot are required at the input to the dimmer to supply power to the electronics. At full on a complete full cycle does not occur. Triggering starts at about 24% of 180 deg or 43 deg. This really does not have a very great effect on maximum brightness. The trigger point at minimum dimming is about 80% of 180 or 144 deg. On an incandescent this reduces the light output to about 5% of the full on brightness.

Another feature of a "three wire" dimmer is that if at minimum setting and after input power is lost that on return of power the dimmer functions at its original setting. Some "two wire" dimmers will not restart at low dimming levels after power returns.

The Lutron data sheet for this dimmer can be found by going to www.lutron.com and then put 032-047c in the search box, and init search. Then you have to pick the link to the .pdf and open it.

There are actually 5 wires to the SF-10P. One additional wire is the EGC to the metalwork. The other is a switched full voltage output that goes to the dimmable ballast to provide constant power to the fluorescent filaments independent of the current thru the fluorescent.

.

 

[cadpoint]

Gar:

Excellant reply, thanks for the refresher!

 

[ssynoground]

Trying to dim Sylvania Compact fluorescent floods which are marked dimmable. Sylvania sent a list of recommended Lutron dimmers but Lutron customer service told me that they havn't tested any Sylvania lamps on their dimmers and don't warrant dimmers used with that product. When I used Lutron or P&S dimmers the lamps always flicker or go out. Any suggestions?

I have two vanity lights that use two medium base bulbs. In these, I have dimmable CFL's, and I'm using a rotary type dimmer. I've had better success with these "old school" dimmers on dimmable CFL's. I've noticed the electronic dimmers are subject to malfuntion with dimmable CFL's and the new LED type bulbs. I'll get the type of bulb I'm using and post it at a later time.

 

[gar]

100323-1653 EST

ssynoground:

What do you mean by a rotary type dimmer? Are you referring to a variable auto-transformer (Variac or Powerstat)? If so, then your results may be fairly good using variable amplitude sine wave excitation to a standard CFL.

I just got a Sylvania dimmable 24 W bulb. With the Lutron dimmer of my previous post the light output is adjustable from 44 to 28 FC for the location of my light meter. This is a range of 100% to 64%. Ballpark same as GE and Phillips.

With this dimmer and on for only a short time there is no significant flicker.

.

 

[jcw48]

Home Depot now carries a Leviton slide preset dimmer made for CFL's. I haven't tried it yet.

http://www.leviton.com/OA_HTML/ibeCCtpSctDspRte.jsp?section=30614&minisite=10026

 

[gadfly56]

100323-1653 EST

ssynoground:

What do you mean by a rotary type dimmer? Are you referring to a variable auto-transformer (Variac or Powerstat)? If so, then your results may be fairly good using variable amplitude sine wave excitation to a standard CFL.

I just got a Sylvania dimmable 24 W bulb. With the Lutron dimmer of my previous post the light output is adjustable from 44 to 28 FC for the location of my light meter. This is a range of 100% to 64%. Ballpark same as GE and Phillips.

With this dimmer and on for only a short time there is no significant flicker.

.

I'm going to guess a Variac type dimmer. Long ago when I was young and foolish (as opposed to old and foolish now) I was head gaffer at a community theater. To save a few bucks, we installed dimmable CFL's for the house lights. I found that the Variac gave smooth dimming from 100% down to about 10% as indicated on the Variac dial. I don't know what this translates to in an actual foot-candle curve but the low end looked pretty dim to me. At 10%, the CFL's simply cut out.

I also found that if you install an incandescent lamp in the same circuit as a bunch of fluroescents on a lighting board power pack, you can dim the fluorescents. Don't know how, but I bet someone here can give the gory details. :grin:

 

[kjw444]

I had the same problem. What I found is that the lamp must match dimmer. I found Phillips dimable cfls work good with a electronic lutron dimmer. Talk to your lighting rep and they should be able to match you up. What a headache! The counter guy gave me the run around saying each lighting circuit had to be dedicated and a bunch of other bs.Then I got the manager and he helped me out. That was after the basement was wired and drywall hung. lamps and dimmers must match or else nothing really happens should get interesting real soon!!

 

[gar]

100323-2246 EST

There is a big difference in the characteristics of CFLs from different manufacturers, whether the CFLs are standard or dimmable, and probably where in the development cycle of a particular manufacturer.

For example my GE dimmable quits with sine wave excitation at near 95 V, whereas the Sylvania I purchased today operates down to about 50 V. From 120 to 95 V neither has more than several % change in light intensity. Thus, these are good lights to eliminate flicker if you have varying line voltage.

.