The Latest in CFL Lighting Technology and Dimmers

I. Overview

Compact Fluorescent Lamps (CFLs) are the subject of no small amount of controversy, but the truth is that the latest CFLs have made huge strides. While they have been more efficient and cooler burning than incandescents from the start, they've been criticized for inconsistent light quality, buzzing and other deficiencies - their non-dimmability among them.  While it's true that you can't dim most CFLs, dimmable CFLs are now available. When paired with a compatible switch, dimmable CFLs are an affordable, efficient, high quality lighting alternative.  This article briefly explores the obstacles that CFLs have encountered on the road to dimmability in the past, and how those issues have been addressed.

II. The Basics

Incandescents dim easily basically because they're a pretty primitive technology.  You create light in an incandescent by running an electrical current through a tiny filament - it just gets hot and lights up (in fact, 90% of the energy used by an incandescent light is emitted as heat).  That's it.  So if you run less electricity through it (by using a dimmer), it heats up less, and gives off less light.

CFLs, on the other hand, create light by sending a high frequency electrical charge through a gas trapped inside a glass tube.  (This is where mercury comes in: a CFL needs mercury gas in order to work properly, and mercury is a toxic substance.  On the flip side, the amount of mercury in newer CFLs really is negligible - a small fraction of the amount in an old thermometer, and less than is released into the atmosphere by the coal you need to burn in order to power an incandescent bulb).  It gets more complicated though, because you can't just run wires from the wall straight into the gas - you need something to convert your household electrical current into the proper high frequency signal.  That's what a ballast does: that's the heavy white part at the base of most CFL bulbs, and it's what actually powers the CFL.  Some CFLs (all older ones) have magnetic ballasts, which is why some bulbs flicker when you first turn them on - they just don't work that well.  Newer CFLs have electronic ballasts that do a better job of regulating the current, so, no more flickering.

Any ballast, though, needs enough power to be able to operate properly.  So if you try to dim a regular, non-dimmable CFL, what you're actually doing is cutting power to the ballast, so it can't do its job.  It would be like trying to dim a TV - it just doesn't work.  On a lot of dimmers, too, "full" power is actually only about 80% - so if you plug a CFL into a socket on a dimmer, even without actually dimming it, the ballast doesn't have enough electricity to power the light.

However, some CFL manufacturers were clever, and have made ballasts that will not only continue to operate with less power, but will also deliver less power to the bulb itself.  What makes a CFL dimmable is this specialized ballast, which is why they are a bit pricier than normal CFLs.  Rest assured that even so, they'll pay for themselves and then some.

The story continues, however, because not all dimmers are created equal. While some dimmers adjust the current flow to the light - giving the light less power - cheaper dimmers work by modifying the purity of the waveform coming from the wall, essentially giving the light the same amount of power, just for less of the time during a cycle. A cycle happens in only 1/60th of a second, but since ballasts operate at a high-frequency (or operate 'faster' than regular power, essentially), they notice these little power cuts - big time - in most cases, causing a ballast - even a 'dimmable' one - to stop working, or to work intermittently.

III. Taking it on

The key to upgrading your dimming lights is to get a new dimmable CFL, and connect it to a good, high-quality dimmer switch - specifically, one of the reduced-current-flow-type dimmers, and not their cheap, power-swindling brothers. In our trials we've found two dimmers that work particularly well.

Remember that plugging in a non-dimmable CFL to a dimmer switch will definitely not work, and it might even damage the bulb - so, best to avoid it.  Dimmable CFLs, however, work great.  We've got two in our kitchen - great light, no problems.