I do not see well. I need lots and lots of light in order to be comfortable and happy. My whole life long I have struggled to find lamps that would allow 100 W bulbs, most of them were restricted to 60 W. I would live dangerously and use 100 watts all the time anyway and I know I was very bad for doing that. But nothing ever blew up or started a fire.
Anyway, now we live in the world of LED bulbs. I get very excited at the idea of a 14 or 15 W bulb putting out the supposed equivalent of 100 W. My assumption is that I can freely and safely use “100 W equivalent” bulbs so long as the base is the same, ( E 26). Even if the lamp manufacturer says don’t exceed 60 W, they are referring to standard old-fashioned true wattage, not modern LED “equivalent” wattage. Right?
If I’m good so far, my next questions are about the genuine brightness of the light as well as the quality and what factors will guide me to the lights that will make me the happiest.
The listings refer to “K” and “lumens” and the terms “daylight/bright/white/soft”.
I know that lumens refer to the power output, or shall we say, perceived power output, since I have found in other instances that lumens seems sort of subjective, and obviously the various terms are subjective, although they appear to be standard in the industry. But for instance, I’ve seen photographs of “soft” light and it looks yellow to me.
And who freaking knows what K means… I assume some of you guys do.
In a magical universe, I would grab a bunch of bright midday sunshine and release it in whatever room I’m in at whatever time, since I can always see clearly in bright daylight, like mostly everybody else. But I don’t trust that the “daylight” really means daylight, and I don’t wanna blind myself with overly bright “white”… Anyway, can you help me make a decision by helping me understand a little better what this all means? Thanks!
The K is kelvins, and refers to the temperature of the light. Actual sunlight is around 6000 kelvins, but incandescent light bulbs were almost all well below that (a true 6000 K incandescent lightbulb is theoretically possible, since that’s slightly below the melting point of tungsten, but it would be extremely difficult, expensive, and impractical). A lower color temperature will result in a reddish cast to the light.
For an incandescent bulb, the color temperature was literally the temperature of the filament. LED bulbs don’t actually produce a thermal spectrum, so there, what it means is that it looks, to the eye, the same as theoretical incandescent bulb at that temperature. Because LED bulbs don’t actually produce a thermal spectrum, it would be possible to get a 6000 K effective color temperature out of them, though you still probably wouldn’t usually bother, since cooler temperatures are considered good enough for almost all purposes (as evidenced by how long we managed with incandescent bulbs).
I have bought a couple of “daylight” LED bulbs; at least for the ones I bought, I found the light to be very “white” and rather harsh.
Otherwise, I’ve been buying “soft” LEDs, and have found them to be more comfortable, as far as the color/quality of the light, and at least reasonably comparable to the old “soft white” incandescent bulbs.
The power draw is the lower figure. 100 Watt light output but only 14 Watts of power drawn. So a 60 Watt rated lamp will do fine. The bulbs still get warm to even hot, but not near the incandescent ones temperatures.
Lumens are an objective measure, what they are is photometric units so they are weighted based on the perceptual properties of the human visual system, using a “standard observer” which is an average of data collected from a few subjects in the 1930s. So it doesn’t necessarily fit everyone’s perception, but it’s a defined value.
K is Kelvin, and is a representation of the color something would be if heated to that temperature (K = celsius + 273.15). It’s not the actual temperature of the bulb of course. Lower numbers are more red and higher more blue, just think of lower ones as being closer to the “warm” colors of an incandescent bulb, and higher ones can be brighter but also “harsh” in some settings.
You can generally use LED bulbs in the same fixtures as incandescent bulbs, but any dimming features and you should probably replace the switch with an LED compatible one as they won’t dim properly and linearly and may impact bulb life. This is fairly easy as DIY or you can get an electrician to do it quickly.
Colour temperature is confusing, because hotter light is commonly referred to as “cooler” and colder light is commonly referred to as “warmer”.
Allow me to illustrate:
Colour temperature described in Kelvins is referring to the spectrum of light given off by a blackbody radiating at that temperature. The hotter the body, the higher energy (higher frequency, shorter wavelength) the average photon emitted, and this scales up from infrared at the low end to red through blue and eventually ultraviolet.
When we colloquially talk about “warm light” and “cool light” in terms of photography or domestic lighting, the scale is the exact opposite. We associate redder light with warm things - fires, candles, etc, and bluer light with cooler things, like overcast days. These terms are not talking about the colour temperature.
Most incandescent bulbs were in the 3000-3500K range, and this is what most people find most comfortable for living spaces. For work spaces, I prefer higher temp (cooler) light, 5000K or so.
To the OP - A little hijack here:
If you intend to install LED bulbs in a enclosed fixture, buy bulbs that are rated for enclosed fixtures. The bulbs will last a lot longer.
The former is 100 watts of equivalent light output (i.e. equivalent to the lumens produced by a 100 watt incandescent), else the bulb would be violating a fundamental law of physics.
In other words, let’s say you want a light bulb that can produce 1600 lumens of light. Here are your choices:
An incandescent light bulb that draws 100 watts of power from the wall outlet.
A fluorescent light bulb that draws 24 watts of power from the wall outlet.
An LED light bulb that draws 14 watts of power from the wall outlet.
Again, each puts out the same amount of light (1600 lumens). For #2 and #3, we say the bulb has an equivalent power of 100 watts.
I did a thread on this a while ago, and found that I like 2800 K LED bulbs, for both my home spaces and my office. I got migraines very quickly from the LED tubes that the landlord installed in my office. I had them take them out and rely on two desk lamps and one floor lamp, all with approximately 2800 K. (The floor lamp is a tri-light, so not 2800 at all three settings.)
Works for me, while I would likely be going home with a headache on a regular basis with 5000 K lights.
Don’t know if that helps, Stoid. Just an anecdote and YMMV.
I hate all of the LED bulbs I have purchased. They leave a sickly bluish/jaundiced glow that impacts me viscerally to the point where I think I will just end up buying a bunch of table top candles lol.
I’ve been cannibalizing all of my unused/rarely used light fixtures and I might have enough old style bulbs to last the year and then I don’t know what I will do.
I am studying @Gorsnak’s graphic with interest though so there might be some hope. Thank you for that illustration and explanation.
The color spectrum of them is improving all the time. They’re still not as rich as an incandescent bulb, but getting there. Above my bathroom mirror, I compromise by using one LED (warmish tone) and one soft white incandescent bulb.
By work space I meant workshop, not office. Sorry, could have been more clear on that. On a work bench you want bright like the sun, and the sun is round about 5800K.
My guess is you weren’t getting headaches from the colour temperature, but either high frequency flicker (guessing those were drop-in LED tubes running off fluorescent fixture ballasts?) or a really crappy CRI spec.
CRI (Colour Rendition Index) refers approximately to how well the spectrum of light emitted from a bulb matches the spectrum of an incandescent source. You can have a light of any given colour temperature that nonetheless has really spiky output if viewed on an amplitude by frequency chart, which can result in certain coloured objects looking wonky etc. Better bulbs these days don’t display these characteristics as much as they used to. Unfortunately, it can be hard to find CRI ratings on bulb packaging, but if possible you want over 90 (out of 100).
That was my fear as well until folks here explained the K thing. I hate fluorescent bulbs and that’s what all the LED bulbs seemed to be like. I had to hunt for 2800 K bulbs, because not every store stocks them, but i had good luck at Lowes.
You may well be right; I dunno. They just were so bright!
Several people on my office floor asked to have them taken out and brought in their own desk and floor lamps. There were a lot of jokes that the O+H unit should be buying us all green eye shades, like in movies set back in the 19th century.
Thank you to all my dope nerds and, like others, found Gorsnak’s contribution to be the most helpful and enlightening… pun was not intended, but now that I think about it…
something else to consider when using LED’s is whether it’s pointing at you or up at the ceiling or in a fixture.
LED’s are extremely focused. They will bore a hole in your brain if pointed strait at you unfiltered. You’ve probably noticed this with new car headlights. I have (3) 2700 Kelvin bulbs in my ceiling fan pointed down at me. The bulbs are frosted to defuse the light. If not for the frosted bulb they would be hellishly annoying.
I like the 2700 Kelvin for my bedroom but I would want a higher number for a reading light.
har 
har…