Flourescent Dimmers
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Re: Flourescent Dimmers
A very brief answer (more a comparison):
Incandescent dimmers control the voltage and power to the lamp. They dim the light by reducing the voltage to the light.
For fluorescent dimmers, the dimmer switch is basically just a relay for information. You set the dimmer at the light level you want, and the dimmer tells the ballast how much hard to drive the lamp. The ballast actually does all the dimming work. It controls the power to the lamp by varying the current to the lamp.
Steve
A very brief answer (more a comparison):
Incandescent dimmers control the voltage and power to the lamp. They dim the light by reducing the voltage to the light.
For fluorescent dimmers, the dimmer switch is basically just a relay for information. You set the dimmer at the light level you want, and the dimmer tells the ballast how much hard to drive the lamp. The ballast actually does all the dimming work. It controls the power to the lamp by varying the current to the lamp.
Steve
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Flourescent Dimmers
I think it varies by design. I think Steve just described a three-wire (+G) design.
I've wired normal recessed cans normally (2-wire), and installed "dimmable" fluorescent R-lamps (in quotes, because I'm not certain they're different from others).
I then will install a fluorescent dimmer from Lutron. (As soon as I go back up there, the dimmer's waiting on me, as it has been for almost two months now...
)
I think it varies by design. I think Steve just described a three-wire (+G) design.
I've wired normal recessed cans normally (2-wire), and installed "dimmable" fluorescent R-lamps (in quotes, because I'm not certain they're different from others).
I then will install a fluorescent dimmer from Lutron. (As soon as I go back up there, the dimmer's waiting on me, as it has been for almost two months now...
)Re: Flourescent Dimmers
What do you mean by a "R-lamp" George? Is this an incandescant can light with a fluorescent lamp installed??
All fluorescent lamps need a ballast. (If they are the new compact kind you install in an incandescent fixture, they have the ballast built right into the lamp housing).
In general, a ballast is made to regulate the power to the lamp (and the light output). So if you just vary the input voltage to the ballast, it will normally try to compensate by boosting the output current. So just varying the input voltage to the ballast doesn't work like varying the voltage to an incandescent lamp would work. That's why I say the ballast does the dimming, and the switch just tells it how much power to put out.
There may be a few fluorescent lamp-ballast combinations that don't fit this description, but I think most do.
As a side note, I have seen people run a fluorecent ballast from a regular dimmer switch. It does work (at least sometimes), but you don't get a very good range, it's hard to adjust, and the lamp doesn't start in a reliable way. In effect, you get something that might half work.
Steve
What do you mean by a "R-lamp" George? Is this an incandescant can light with a fluorescent lamp installed??
All fluorescent lamps need a ballast. (If they are the new compact kind you install in an incandescent fixture, they have the ballast built right into the lamp housing).
In general, a ballast is made to regulate the power to the lamp (and the light output). So if you just vary the input voltage to the ballast, it will normally try to compensate by boosting the output current. So just varying the input voltage to the ballast doesn't work like varying the voltage to an incandescent lamp would work. That's why I say the ballast does the dimming, and the switch just tells it how much power to put out.
There may be a few fluorescent lamp-ballast combinations that don't fit this description, but I think most do.
As a side note, I have seen people run a fluorecent ballast from a regular dimmer switch. It does work (at least sometimes), but you don't get a very good range, it's hard to adjust, and the lamp doesn't start in a reliable way. In effect, you get something that might half work.
Steve
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Flourescent Dimmers
I am 90% sure that this is the dimmer. The part number is eerily familiar.
If all works as planned, a CFL R30 similar to this will function correctly.
We'll see when I put the juice to it.
Edit:
I think I'm going to need to shoot my supply guy:
[ January 25, 2006, 09:45 PM: Message edited by: georgestolz ]
I am 90% sure that this is the dimmer. The part number is eerily familiar.
If all works as planned, a CFL R30 similar to this will function correctly.
We'll see when I put the juice to it.
Edit:
I think I'm going to need to shoot my supply guy:
[ January 25, 2006, 09:45 PM: Message edited by: georgestolz ]
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Flourescent Dimmers
Check out this article, towards the bottom:
Check out this article, towards the bottom:
So, you wanna bet my supply gotten us 2 $80 dimmers when a simple dimmer would do just fine?
peteo
Senior Member
- Location
- Los Angeles
Re: Flourescent Dimmers
Trying to find out how fluorescent dimming works. Disappointing to find very little information for us cows out there.
What was found at GE and Lutron are not very informative. I couldn't find the right article at the Rensselaer site
http://www.lrc.rpi.edu/index.asp
A professor from Hong Kong, it seems, is the one with something to say:
http://www.building.com.hk/forum/07_00electronic.htm
Trying to find out how fluorescent dimming works. Disappointing to find very little information for us cows out there.
What was found at GE and Lutron are not very informative. I couldn't find the right article at the Rensselaer site
http://www.lrc.rpi.edu/index.asp
A professor from Hong Kong, it seems, is the one with something to say:
http://www.building.com.hk/forum/07_00electronic.htm
- Location
- Massachusetts
Re: Flourescent Dimmers
Check out the info available at Advance.
They offer many good files.
Advance Literature
Check out the info available at Advance.
They offer many good files.
Advance Literature
- Location
- Massachusetts
Re: Flourescent Dimmers
Electronic ballasts both standard and dim-able have been around quite a while now.
T-5 HO or T-8 fluorescent fixtures are now replacing HID lighting in low and high bay applications.
Here is an example
4 Light T5HO Fluorescent High Bay 120 - 277V
This fixture replaces a 400 Watt HID and uses half the power.
Peteo, what this professor has to say is nothing new.
Electronic ballasts both standard and dim-able have been around quite a while now.
T-5 HO or T-8 fluorescent fixtures are now replacing HID lighting in low and high bay applications.
Here is an example
4 Light T5HO Fluorescent High Bay 120 - 277V
This fixture replaces a 400 Watt HID and uses half the power.
Re: Flourescent Dimmers
Perhaps all of us are aware that when a flourescent lamp is on, it can sustain a wide fluctuation in voltage without causing any substantial effect on the intensity of light. I could not understand Mr. Steve explanation that dimming is obtained by varying the current, because the ballast of a flourescent lamp is inductive in nature and inductive reactance Xl=2xpiexfrequecyxinductance. Given this fact that frequency of the supply cannot be changed, inductance for the ballast is fixed, how will you change the current??
Perhaps all of us are aware that when a flourescent lamp is on, it can sustain a wide fluctuation in voltage without causing any substantial effect on the intensity of light. I could not understand Mr. Steve explanation that dimming is obtained by varying the current, because the ballast of a flourescent lamp is inductive in nature and inductive reactance Xl=2xpiexfrequecyxinductance. Given this fact that frequency of the supply cannot be changed, inductance for the ballast is fixed, how will you change the current??
- Location
- Massachusetts
Re: Flourescent Dimmers
You can not dim a standard magnetic ballast, you can dim some electronic ballasts, they are capable of changing the frequency, current and voltage supplied to the lamps.
Re: Flourescent Dimmers
It seems that no one has explained this thing yet, so here goes:
First, the fluorescent lamp is not inductive. The magnetic ballast is inductive.
Second, the voltage across a fluorescent lamp is moreorless constant. The magnetic ballast, an inductor, limits the current to the lamp.
Third, the electronic ballast generates a high frequency (10-20KHZ) sinusoidal voltage which is applied to the tube through a small inductor--a magnetic ballast if you will.
Fourth, varying the frequency will cause the reactance of this inductor to change which in turn changes the current in the lamp.
It seems that no one has explained this thing yet, so here goes:
First, the fluorescent lamp is not inductive. The magnetic ballast is inductive.
Second, the voltage across a fluorescent lamp is moreorless constant. The magnetic ballast, an inductor, limits the current to the lamp.
Third, the electronic ballast generates a high frequency (10-20KHZ) sinusoidal voltage which is applied to the tube through a small inductor--a magnetic ballast if you will.
Fourth, varying the frequency will cause the reactance of this inductor to change which in turn changes the current in the lamp.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Flourescent Dimmers
So, has anybody worked with the dimmable compact fluorescent lamps? Is my read on this correct, that they all use regular incandescent dimmers?
Thinking back, my co-worker and I were kinda puzzled that the lamp manufacturers were bragging so openly about having "dimmable" bulbs if you had to buy an $80 dimmer to make them work!
It would make a lot more sense if they were compatible with a standard dimmer.
I can't be 100% sure, because the lamps we got were similar looking to the GE lamp I linked to above, but not GE. And the article I found was applauding GE for their product (which concievably they could have patented and guarded their idea).
But I found nothing on the packaging of the bulbs I installed calling for a special dimmer, either.
I just want to be sure I'm 100% right on this one. (I'm going to give my supply guy trouble anyway, but...)
[ January 26, 2006, 08:40 AM: Message edited by: georgestolz ]
So, has anybody worked with the dimmable compact fluorescent lamps? Is my read on this correct, that they all use regular incandescent dimmers?
Thinking back, my co-worker and I were kinda puzzled that the lamp manufacturers were bragging so openly about having "dimmable" bulbs if you had to buy an $80 dimmer to make them work!
It would make a lot more sense if they were compatible with a standard dimmer.
I can't be 100% sure, because the lamps we got were similar looking to the GE lamp I linked to above, but not GE. And the article I found was applauding GE for their product (which concievably they could have patented and guarded their idea).
But I found nothing on the packaging of the bulbs I installed calling for a special dimmer, either.
I just want to be sure I'm 100% right on this one. (I'm going to give my supply guy trouble anyway, but...)
[ January 26, 2006, 08:40 AM: Message edited by: georgestolz ]
- Location
- Massachusetts
Re: Flourescent Dimmers
Not one that I can think of would have worked with a standard incandescent dimmer. That is not to say I doubt you in the least that some are available.
Two types I am familiar with.
One type takes three wires between the dimmer and the ballast, Neutral, Switched Hot, and a 'control' hot that the voltage is varied to control light output.
Another type gets two line voltage wires, hot and neutral, the hot is switched to apply power to the ballast. Than another pair of low voltage leads is daisy chained from the dimmer to each ballast. The ballast adjust the voltage on these low voltage leads from 0 to 10 volt.
In both cases the ballast have to be compatible with the dimmers.
I have installed many dimming florescent fixtures.
Not one that I can think of would have worked with a standard incandescent dimmer. That is not to say I doubt you in the least that some are available.
Two types I am familiar with.
One type takes three wires between the dimmer and the ballast, Neutral, Switched Hot, and a 'control' hot that the voltage is varied to control light output.
Another type gets two line voltage wires, hot and neutral, the hot is switched to apply power to the ballast. Than another pair of low voltage leads is daisy chained from the dimmer to each ballast. The ballast adjust the voltage on these low voltage leads from 0 to 10 volt.
In both cases the ballast have to be compatible with the dimmers.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Flourescent Dimmers
I have a dimmable CF lamp, I use it with an X-10 lamp module and it dims just fine. Its nothing special, I got the lamp at a big box store.
I have a dimmable CF lamp, I use it with an X-10 lamp module and it dims just fine. Its nothing special, I got the lamp at a big box store.
Re: Flourescent Dimmers
Best to explain how flourescent light works.
Igniting requires a high voltage to energize the gas. This is the starter circuit, and for typical home light is about 180 volts.
Once ignited the flourescent light acts like a zener diode based on the ionizing voltage of the gas. It will limit voltage at a certain level. For typical home lights, this is about 60 vac which is why there is a ballast to limit current. A higher wattage bulb has a lower reactance ballist. You need a current source to run the bulb, more current, more brightness, less current, less brightness, but bulb voltage in all cases remains at about 60 vac.
You can dim the bulb by increasing the ballast inductance. This is not easy to do in a conventional setup since just putting a variable step inductor in series will likely screw up the startup igniting process.
A dimmible CFL uses the reduced conduction sense from a typical triac dimmer to adjust the constant current source circuit, thereby dimming the bulb. This circuitry does not exist in a normal (non-dimable) CFL.
Best to explain how flourescent light works.
Igniting requires a high voltage to energize the gas. This is the starter circuit, and for typical home light is about 180 volts.
Once ignited the flourescent light acts like a zener diode based on the ionizing voltage of the gas. It will limit voltage at a certain level. For typical home lights, this is about 60 vac which is why there is a ballast to limit current. A higher wattage bulb has a lower reactance ballist. You need a current source to run the bulb, more current, more brightness, less current, less brightness, but bulb voltage in all cases remains at about 60 vac.
You can dim the bulb by increasing the ballast inductance. This is not easy to do in a conventional setup since just putting a variable step inductor in series will likely screw up the startup igniting process.
A dimmible CFL uses the reduced conduction sense from a typical triac dimmer to adjust the constant current source circuit, thereby dimming the bulb. This circuitry does not exist in a normal (non-dimable) CFL.
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