New Light Fixture with Dimmer?

[lbaccar23]

I just installed a Hampton Bay hanging dining light fixture. It uses 10 20 amp halogen bulbs and also has a seperate fuse in the "canopy". I guess it is high voltage converted to low voltage. I connected this to an existing Dimmer switch and the instructions do not specify if this is good or bad. However, I hear a ballast like humming sound coming from inside the "canopy" connected to the ceiling. The lower I dim the light the louder the humm. Is there a certin dimmer i need to use with the fixture or should i be using a plane toggle switch?

[Rewired]

Ten- 20 watt lamps, ones with two tiny prongs on the end?
It sounds like the fixture does use "low voltage" lamps and has a transformer in the top canopy.. You should be using a dimmer that is compatible with "low voltage" lighting . You can get them at Home Depot but they are a lot more expensive, and there is no guarantee that will cure the buzzing from the transformer in the light.. You could try it and see what happens, I would for the hell of it!

A.D

[lbaccar23]

Yes Exactly...the ones with the two tiny prongs. I went to one HomeDepot and they were out of the low voltage dimmers so I bought and installed a regular toggle switch for now and that seemed to cure the humming noise. I aslo tried installing a lutron dimmer that was for halogen and incandescent lights..didnt specify high or low voltage so i guess it was for high voltage and it was only about $7 and judging by ur comment that low voltage dimmers are much more expensie. So I can find a low voltage dimmer that is less the $15 ill try that. If not ill stick to the on/off switch. Thanks a bunch.

quote:Originally posted by Rewired

Ten- 20 watt lamps, ones with two tiny prongs on the end?
It sounds like the fixture does use "low voltage" lamps and has a transformer in the top canopy.. You should be using a dimmer that is compatible with "low voltage" lighting . You can get them at Home Depot but they are a lot more expensive, and there is no guarantee that will cure the buzzing from the transformer in the light.. You could try it and see what happens, I would for the hell of it!

A.D

[lbaccar23]

I bought and installed a low voltage dimmer for 15$. Howver, I am still getting a loud humming noise especially when I dim to the middle. Any other suggestions?

[Rewired]

I can't say there is much more that you can do unless you replace the transformer in the upper canopy with one of a different manufacturer. Yet again there is no guarantee that will cure the problem. The transformer up top is going to be a fair size as well as it has to be good for at least
200 "volt-amps".. You either have to bear the buzz or change back to a standard switch unfortunately.

A.D

[lbaccar23]

I called some manufactur representative about the problem and suggested to install a 'dimmer coil' or 'debuzzer coil' inside the canopy. Has anyone heard of this type of device? Home Depot had no clue. Suprise[]

[Rewired]

A WHAT????
Sorry I can't say I have ever heard of one of them!

A.D

[HayZee518]

Sir, the dimmer changes AC into pulsating DC direct current. Straight DC is not compatible with a transformer - it just won't work - your pulsating DC is acting like ac but the transformer inside the fixture doesn't see it as pure ac. Eventually the transformer will burn up.

[Rewired]

Actually, that is NOT correct.. a dimmer's output is actually [u]A.C</u> but with the use of a "Triac" that conducts or "fires" at a certan time, it will only "conduct" at certan parts of the A.C sine wave. The longer its "conducting" the longer the current flows to the lamp or transformer and the brighter the light will be.. If you look at the output on an ocilloscope at "full brightness" you will see a full A.C sine wave. As you "dim" the dimmer, the output will resemble a sine wave with "pieces missing" Its hard to explain, hard to explain what it looks like because I tried that long ago.
Using a REGULAR dimmer on a low voltage fixture may burn out the dimmer because of the sudden "inrush" that occurs when you power up any inductive load, i.e a transformer winding. Using a dimmer thats rated "low voltage" probably is similar to a regular dimmer only it will have some kind of choke coil inside to prevent the inrush of a transformer from cooking the dimmer components AS WELL as a "varistor" or some way of dissipating that high voltage "spike" you get when you de-energize an inductive load. that spike will cook a regular dimmer fast too. I don't know for sure, I have never taken one apart but the only reason I think the transformer is humming is its probably not a quality unit, I dont know.. all i know is you CAN dim "low voltage" lighting and the ol' Hammond transformer I use to supply the puck lights under my kitchen cabinets is quiet as a mouse!!
A.D

[HayZee518]

Rewired - thanks for the advice. All taken wisely. I know what you're talking about observing the sine wave on the scope. It chops out portions of the wave.

[Rewired]

HayZee518:
I apologize if I souned a bit like an ass.. I can sometimes!!

[mburke911]

Hello,
I just installed a lutron combination on/off/dimmer switch from home Depot which controlls a light with six 100 watt standard bulbs. The dimmer is rated for 600W so that shouldn't be an issue. The lights now humm like described earlier. The humm gets louder when the dimmer is activated with the loudest point at the lowest light setting.
I tried replcing the switch which did nothing. I tried replacing the bulbs with 75W bulbs. Also didnot stop the humming. What can I do to stop this? It even hummed when there was only one bulb in the fixture.

Any help would be apreciated.

Mark

[kactuskid]

Is the dimmer buzzing or are the bulbs buzzing? What a dimmer basically does is turn the light bulbs off and on very rapidly so the buzzing sound comming from a bulb is actually the vibration of the filiment turning on and off. Replacing the bulbs with a different brand of bulb, one of better quality will sometimes work. GE and Sylvania seem to work best. Also installing a lesser wattage bulb or a rough service bulb may work.

You can also buy a better quality dimmer, the cheaper dimmers will buzz so I prefer the ones in the $20.00 and up range. And last but not least, you can install a lamp debuzzing coil (LCD) in series with the dimmer.

[lbaccar23]

Fixed Dimmer

Recently the original dimmer that I installed blew out. I tried to get an exact (low voltage [250watt] electroinc dimmer) replacement but a few HomeDepots did not have the same one. After some investigation, I came to the conclusion that the light fixture is magnetic and not electronic. Hence, the dimmer should be to control for the same. And since the first dimmer was electronic, I was getting a humming sound from the mismatch i suppose and I assume that is why it went bad so quickly. I installed the new (magnetic) dimmer and no longer get a humming sound.

[SSN596]

Well, the transformer is certainly of the highest quality that a sweat shop in the back woods of China can produce. That is one issue.

As far as the voltage waveform, once the dimmer starts switching, the output is no longer a pure sine wave. It is slices of a sinusoidal pattern, but a transformer does not necessarily see it that way. This is evidenced by the fact that the hum gets worse as you dim further down. Obviously, Hampton Bay ( which is Air Cool Industrial Corp, North American HQ I belive is in Canada) is aware of the issue, and should be pressed to give you a fix, rather than just tell you to install some mystery coil.