I am wondering if it is an unavoidable side-effect of dimmer switches that an electric buzz can be heard whenever the bulb is not turned up to full power.
The specifics: I have a ceiling fan, which, due to either a lack of foresight or the cheapness of the original contractor, has only one wire running through the wall from the switch to the fan. When I orignally bought my condo, it was set up so that if I dimmed the built-in light fixture, it would also “dim” the power that feeds the fan. Obviously, that was no good, so I got one of those remote control devices that allows the power to be split at the ceiling with a ring that attaches between the ceiling and the fixture. Now I can operate the light and fan separately. However, if I dim the light even a little bit, I can hear an annoying buzz.
I also had another ceiling fixture installed, where previously there wasn’t one. This one has the dimmer switch built in to the wall switch, and is attached to a chandelier-type light fixture. This also has a pronounced buzz if not at full power.
Both were installed by a professional, as I make it a rule not to futz around with electricity whenever possible.
My questions:
Is this normal and/or unavoidable?
Did the “professional” do something wrong?
Currently, I am using regular 60W bulbs- are there bulbs that are specifically designed for these applications that would avoid this buzzing?
Barring any other easy fixes, is there anything else that can be done to eliminate this annoying buzz, short of not dimming the lights?
Your light is wired incorrectly. This is what is called a 60 hz hum, and it means that you need a proper ground, or wires with better shielding. Have him come back and fix it.
I’ll have to disagree with Morgainelf. The 60hz hum that’s a common gremlin in sound equipment is something quite different.
In my experience the buzz you’re hearing is normal or at least very common. Some bulbs do it louder than others, but AFAIK, you’ll just have to experiment, I’ve not heard of bulbs specifically designed to resist the buzz.
I believe this happens because of the way modern dimmers work. Rather than limiting the voltage the bulb sees with a resistor, they use something akin to pulse-width modulation to reduce the amount of time the bulb is connected to the voltage source (see this explanation). The sharp square-wave edges created by the switching tends to make the filament vibrate at the switching frequency and multiples thereof.
Lagged2Death is basically correct. Dimmer controllers are “phased-fired proportional controllers,” and cheap ones induce a lot of high frequency components in the current. This has the effect of mechanically “ringing” the filament.
Some dimmer controllers have built-in filtering to roll-off the sharp transients. This reduces ringing and EMI.
I believe that no explanation will be forthcoming, because the statement is incorrect. Saying that dimmers waste energy is like saying that a regular on/off switch wastes energy if left in the “on” position with the bulb burnt out.
Come to think of it, I think dimmers DO waste energy. But only when used with incandescent bulbs. If you turn down the power on a standard light bulb, it’s light spectrum shifts into the infrared. This means that the light looks much dimmer, even though the actual power hasn’t dropped proportionally. (Seat of pants estimation: dim the light output by half, but the power only goes down by 10% - 20%)
Incandescent light bulbs are extremely inefficient unless you’re using them to heat your house. And a dimmed-down bulb is way more inefficient than usual. To avoid the problem, use dimmable fluorescents.
When I dim the lights, I am using less energy vs. when they were on full brightness. No if’s, and’s, or but’s about it. Sure, it might be more efficient if I instead used an incandescent bulb of lower wattage, and it might be a lot better to use dimming fluorescent lamps, but that’s not the point. The above poster seemed to insinuate that the very act of dimming an incandescent bulb wastes energy. It simply isn’t true.[sup]1[/sup]
[sup]1[/sup][sub]One (rare) exception is when you dim the bulb very slightly, in the narrow window where the energy dissipated by the triac may actually exceed the bulb’s reduction in power.[/sub]
