Cold cathode bulbs are great where you don't need much light, but you'll likely need something else for where you'll be reading.
I use 3W R20s for ambient lighting in (air-tight, gasketed) recessed cans in a low ceiling shed dormer used as an office, but have a reading lamp on the desk in there for when I'm dealing with tiny fonts on the printed page.
I use 2W A-bulbs in sconces for stairwell/alcove lighting which is more than enough dispel the shadows without adding a lot of glare.
I use three 5W A-bulbs in a low hanging down-light fixture over the dining room table, and a pair of 5W in a floor lamp in the living room (which is enough to read by for most peops, but not for some of the 80+ year olds who visit.
8W R30s can work fine in low ceilings or for dining light-levels, but you may want 8W LED with PAR-type photometrics, if mounted 11' up in a cathedral ceiling and you want to read faded newsprint by them. For hallways with fixtures 2' apart 8W cold cathode R30s will be more than enough- even 5W will do. (In my dormer office with the low ceiling the 3W R20s are mounted about 4' apart, and the illumination field is fairly uniform at desk-height, and not-too-glary.)
My front porch has 2 sconces, one on each side of the door with a single 5W A-bulbs in each. I tried 3W there, definitely not enough. When it's cold out it can take 2-4 minutes for the CCFLs to come up to full brightness- they're not the greatest for security lighting. This is another application where a good LED (and they're not all good- most are pretty crummy still) might be a preferable option.
Most of the dimmable cold cathode bulbs I've tried seem almost bi-modal- they don't smooth dimly or over a huge range, and their lowest range is something like half the full-on output. (Unlike conventional CFL technology they don't have filament currents available to exploit for smooth out the transitions, and seem to rely primarily on the relatively high impedance of the tube once struck and the average duty cycle of the AC, but below some minimum dimmer setting the ballast doesn't produce enough voltage to strike.) I have some 3W R20s on dimmers lighting up some art in the living room, but mostly keep them at full-on (or full off).
Dimmable LEDs tend to have a wider range of dimming, but the efficiency &/or color rendering index (CRI) on many are remarkably low. If you go that route, look for CRI of 80 or better, a color temperature of 2500-3000K, no higher (the higher you go in color temp, the bluer it gets, and the crummier skin-tones & food looks.) Efficiency on self-ballasted cold cathode bul aren't all that great either- most are below 50lumens/watt, some R-bulbs are under 40lm/w, but they tend to be cheaper than the best LED equivalents.
Unless you're overwhelmed by the glare at full-on with the existing incandescents, replacing the dimmer with a switch and buying 15W CFLs in bulk cases will be a lot less money up front. By the time they burn out there will be cheaper/better/more-efficient LED R30s available that might make more sense than CCFLs or LEDs at current prices. |