I'm curious about something guys. Energy saving compact fluorescent
bulbs and fluorescent tube light fixtures don't work well at relatively low
temperatures (below freezing) which is why they shouldn't be used in cold
climates in an unheated garage.
Here's my question; how can fluorescent tube light fixtures in outdoor
commercial signs work in cold temperatures? Are they designed different?
P.S.: Fluorescent bulbs can not be operated with the typical light fixture
dimmer. I'm assuming that they require a specialized dimmer. And one last
thought. I like the idea of saving money with energy saving compact
fluorescent bulbs but I don't like the color of their light. What do you
Many signs use HO (high output) lamps and ballasts. There is also VHO (very
high output). Lamp current, thus wattage is much higher in these with a
little expense of efficiency. Of course light output is higher. There are
also lamps that are designed to operate in the cold and there aer sleeves
that fit over the tube to help insulate it.
There are dimmable compact fluorescent lamps available. They don't get the
nice orangey warm glow as does dimmed tungsten.
Different brands give a different color tone. Many rated 2900 K look fine to
me while some look pinkish. Color was never much of a concern to me. I like
lighting a room with 28 watts vs. 120 w.
I have several CF bulbs installed outside, and I live in Canada (where it does,
occasion, drop below freezing). I have them in enclosed fixtures, which I
some of the heat in and allows them to operate at fairly cold temperatures.
Check the packages of the CF bulbs you want to buy - many of them will list
operating temperatures. The ones I bought indicated that they would reliably
to -25 Celsius (-13 Fahrenheit), but I've found that they will run even when
-30 Celsius, but they aren't as bright. Right now it's only a few degrees below
freezing, and they're working just fine.
There is a fair bit of variety out there in terms of CF bulb colour temperature.
some of the bulbs and see what you prefer. Cheap CF bulbs tend to have really
color, but some of the better bulbs are much nicer. Philips bulbs have a nice
Most Cf lamps are 2700 Kelvin, roughly incandescent color, but I see
1. Spirals 19 watts or less tend in my experience to have a less-pink,
more-yellow color, more like incandescent.
2. Higher wattages of all kinds in my experience have a tendency to be
slightly more pink and less yellow. I have found Philips and GE to be
less bad than others in this area.
3. Sylvanias are mostly 3000 Kelvin - slightly whiter than most others.
But I have also found those to be a little harsher - slightly less
yellowish and more whitish-pinkish, rather than halogen-like.
4. Sylvania makes a 3500 Kelvin 13 watt spiral that is whiter still, what
I would call a "semi warm white". They call it "daylight", which is
usually used to refer to a cold pure white or a bluish white color.
I find Sylvania 3500K spirals rather pleasant, despite being a bit
"harsh" by continuing their less-yellow, more-pinkish-white tendency.
They may also look a litle "dreary" when you don't use enough light to
illuminate things brightly.
5. I have noticed a trend where ones with non-electronic ballasts glow a
little less yellow and more pink than ones with electronic ballasts. PL
types don't have ballasts, and most fixtures and adapters I have seen for
them have non-electronic ballasts.
6. Philips makes 15 watt "outdoor" models in 2700 Kelvin and 5000 Kelvin
("daylight" icy cold pure white). These are suitable indoors also except
maybe not in recessed ceiling fixtures because of heat buildup. But you
probably don't want the 5000K one if you are using it indoors for general
7. You may find a few others with various higher color temperatures like
4100 (color of "cool white"), 5000 (icy cold pure white) and 6500 (bluish,
color of "daylight"). My experience is that these usually cause a "dreary
gray" effect in home use. You need high illumination levels (typically
around or over 1,000 lux) to avoid this "dreary" effect.
8. If any FUL types are still around, avoid them. The ones I have seen
have a lower color rendering index.
9. Avoid dollar store ones, especially ones $2 or less and/or of brands
only seen in dollar stores. Most have a "daylight" bluish white color,
even many in packages that say "soft warm white light" or "sun lighting".
In addition, I have yet to see a dollar store one significantly outshine a
40 watt "standard" incandescent, not even ones that claim to replace 150
watt incandescents. Color rendering is also usually a little worse than
that of most non-dollar-store compact fluorescents. Many dollar store
ones that actually are "warm white" have an ugly purplish-pinkish-whitish
shade of "warm white" as well as outright low color rendering index.
- Don Klipstein ( firstname.lastname@example.org)
I have half of my unheated shop lit by 48" 2 tube fixtures. They are
T-8s. I've never had a problem with them in cold weather.
The other half of my shop is lit with CFs. The Cfs definitely take
longer to warm up. The light is more yellow.
Amperage measured isn't really a fair comparison. The total watts of
each half of the shop do not match, the CF side draws more ampres,
while it seems to be darker at times and brighter at other times.When
warm weather comes back, I'll be replacing the CFs with new T-8
fixtures and trashing the CFs.
Tom in KY, It's only taken me 4 years to make that decision.,,That's
about right, ain't it?
Ballasts come in several temperature categories. 50 F, 20 F, 0 F, and -10
At least those are the ones I have installed. The ballast basically has a
heater inside the case to keep the ballast warm. These temps depend on the
application and the manufacture.
HO and VHO lamps are more lumens per watt. Yes they are used on signs, but
because they want the sign to "pop out" of the darkness. Not because they
are better at cold weather.
FYI, Lower wattage CF like 5 and 7 watt do work well in colder weather. We
installed a bunch of CF for outside lighting. We found that the 5 & & watt
ones were good down to ~30 F. Also if they were turned on before the sun
went down and it got colder prevented them from the flickers.
I thought temp rating related to output characteristics to run lamps at
low temp; would think magnetic ballasts wouldn't have anything in them
that would have a problem with cold. They produce heat anyway.
Don't know about lumens/watt but they are used because they are brighter
- more lumens/foot (may be what you meant).
I also thought they were better in cold temperatures because they run
But its been a long time since I worked on signs.
Colors of CFL are becoming standardized. For home use, the standard color
is designed to be a close match to that of standard incandescent lamps. If
you buy a CFL in a retail outlet with the Energy Star symbol on it, you'll
get that color.
To get a "whiter" or "cooler" color, you'll likely have to get a
commercial/industrial CFL product. Look in the lamp catalogs or on CFL
packages for the CFL "Chromaticity" rating in "Kelvins". It works like
2700 K = warm tone (like low-wattage incandescent)
3000 K = warm tone (like high-wattage or halogen incandescent)
3500 K = neutral white tone
4100 K = cool tone (similar to traditional cool white fluoresent)
5000 K and higher = very cool tone like daylight or blue sky
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