Help Me Understand Lightbulb "Measurements"

[SouperGrover]

I am installing florescent lights into my shop and I'm finding I don't know much about how bulbs are measured. It's a 22x19 space, and I have 2 4' 2-bulb fixtures hanging over half the shop for now. The other half I can light later. I know in my house, the higher the wattage the brighter the light. That's all I really pay attention to. But, when I go to buy lights for the fixtures, I see watts, lumens and brightness measurements (3500k, 6000k, etc), warm, day - all in varying configurations. The fixtures take t-12 bulbs. I'm also a bit power crippled and can only have 1 20amp circuit. What bulbs should I get to make sure they draw the least power, but provide me with maximum light?

I'm aware LED lights are brighter and more efficient. These fixtures were given to me by a neighbor and since I'm just getting started with building a shop, I don't want to buy new fixtures if I have free ones

Thanks!

 

[KRB52]

"Lumens", for lack of a better description, tells how much "light" you are getting, or the bulb is giving off. "Wattage" is how much electricity it takes to give off those lumens. Typically, florescent tubes of a given size are all the same wattage.

 

[cybrdyke]

Watts is a measure of energy consumed. We are conditioned to think that if a lamp has more watts, it must be brighter than one that has fewer watts. Everyone knows a 100 watt light bulb is brighter than a 40 watt light bulb, right?
Well, you might as well forget about using watts as a criteria for brightness. With fluorescent and LED it's rarely true anymore. Look on the box for lumens. Lumens (luminous flux) is the amount of light being sent out from the source. This is what you want to know. Your old T12's, if they are 40 watt, delivered 3250 lumens each. To show that watts means nothing, a 40 watt light bulb delivers about 450 lumens. Big difference, eh?
Brightness is not really a technical term, so lets not address that. The kelvin numbers you are seeing, 3500 4000 5000 etc, are telling you the color of the light that the lamp delivers. This is strictly a personal choice. Lower numbers are warmer ambiance. Higher numbers are more blue and have a sterile ambiance. For reference, a typical 60 watt light bulb is 2700k. All the names like warm white, natural white, etc are marketing bunk. If you see a product that doesn't tell you the K color, dont buy it.
Those are the definitions in layman's terms. Of course, it's much more technical than that.
A great solution to your fixtures is to just bypass the ballast and put in LED tubes. There are lots of brands out there. 3M makes a good one. http://multimedia.3m.com/mws/media/1079887O/commercial-3m-led-advanced-light-t8-ballast-bypass.pdf
Good luck
CD

 

[theoldwizard1]

Lux is really the important unit. It is 1 lumen per square meter. The problem is light from most light sources spread out to cover a wider area the farther it is away from the area. Reflectors make a big difference in this measurement.

From Wikipedia, lux is

...used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface

 

[SouperGrover]

Watts is a measure of energy consumed. We are conditioned to think that if a lamp has more watts, it must be brighter than one that has fewer watts. Everyone knows a 100 watt light bulb is brighter than a 40 watt light bulb, right?
Well, you might as well forget about using watts as a criteria for brightness. With fluorescent and LED it's rarely true anymore. Look on the box for lumens. Lumens (luminous flux) is the amount of light being sent out from the source. This is what you want to know. Your old T12's, if they are 40 watt, delivered 3250 lumens each. To show that watts means nothing, a 40 watt light bulb delivers about 450 lumens. Big difference, eh?
Brightness is not really a technical term, so lets not address that. The kelvin numbers you are seeing, 3500 4000 5000 etc, are telling you the color of the light that the lamp delivers. This is strictly a personal choice. Lower numbers are warmer ambiance. Higher numbers are more blue and have a sterile ambiance. For reference, a typical 60 watt light bulb is 2700k. All the names like warm white, natural white, etc are marketing bunk. If you see a product that doesn't tell you the K color, dont buy it.
Those are the definitions in layman's terms. Of course, it's much more technical than that.
A great solution to your fixtures is to just bypass the ballast and put in LED tubes. There are lots of brands out there. 3M makes a good one. http://multimedia.3m.com/mws/media/1079887O/commercial-3m-led-advanced-light-t8-ballast-bypass.pdf
Good luck
CD

Perfect explanation. Thanks! The kelvin measurement of color thing was what was making me scratch my head the most.

I researched the LED ballast bypasses last night. Very interesting... It's hard for me to tell in the videos but LEDs are generally brighter for less power consumption, right?

Right now the walls are a darker, unfinished color. I'm planning on painting the walls white to help boost the lighting, too.

 

[SouperGrover]

Lux is really the important unit. It is 1 lumen per square meter. The problem is light from most light sources spread out to cover a wider area the farther it is away from the area. Reflectors make a big difference in this measurement.

From Wikipedia, lux is

Thanks for that. Most of the bulbs I'm looking at on the store sites don't list this measurement. Like you said, this depends hugely on the environment the light is in and they probably don't want to overpromise.

As mentioned above, I'm hoping that by painting the walls white I will get more reflection of light and a brighter room

 

[Showkey]

^^^^^^^^^ they only list lumens on the bulb.

LUX involves distance and spread so it variable. ( Lumen per Sq. meter thing mentioned prior)

You can measure LUX with a free smart phone app. It's very "enlightening" to actually measure the light getting to the work surface.

Example you may want a 1000 lux on a bench top or table saw for detail work. While general reading or writing might need 300-500 LUX. All this is Varry dependent on ones age.

 

[BFBOB]

Lamps and luminaires (fixtures) are not rated in lux because this is a function of the installation. Same lamp, same fixture, different lux at different distances. Same lamp, different fixtures different lux at the same distance.

Lumens, though are always the same for a given lamp. So if in your usage you don't have bright enough light (enough lux), replacing the lamp with one that puts out more lumens will give you brighter light.

And yes, white paint can work wonders. If your fixtures send a lot of light upward, painting the ceiling white will help quite a bit.

 

[MFolks]

Read this information, about when we age, and the light intensity needed for tasks:
http://www.griotsgarage.com/product...xture.do?sortby=ourPicks&refType=&from=Search

 

[SouperGrover]

You can measure LUX with a free smart phone app. It's very "enlightening" to actually measure the light getting to the work surface.

Example you may want a 1000 lux on a bench top or table saw for detail work. While general reading or writing might need 300-500 LUX. All this is Varry dependent on ones age.

Thant's great! I will definitely have to put it on my phone.

Good to know on the measurements. I am planning on adding station lights to each of my work areas to brighten up when I work. Those numbers are great to know

 

[SMKS]

Here is info on the labeling that the all bulbs are required to have. It includes info about color temperature, etc. It's required by the FTC.
https://www.ftc.gov/tips-advice/bus...g-facts-label-questions-answers-manufacturers

 

[SouperGrover]

Here is info on the labeling that the all bulbs are required to have. It includes info about color temperature, etc. It's required by the FTC.
https://www.ftc.gov/tips-advice/bus...g-facts-label-questions-answers-manufacturers

Thanks! Wish the online retailers would standardize a presentation of all of that stuff on their sites as well...

 

[gtae07]

Am I the only one that constantly has to remind myself that the marketing terms for "cool" and "warm" light don't correspond to blackbody temperature?

 

[cybrdyke]

Thanks! Wish the online retailers would standardize a presentation of all of that stuff on their sites as well...

Alot of online retailers are not located in the USA, thus are not subject to the US laws. Even if they are located in the USA, they will sell products to you and ship them directly from China to you, again... sidestepping the law. They wont have their product tested to have these labels put on them, because they would fail miserably.

Am I the only one that constantly has to remind myself that the marketing terms for "cool" and "warm" light don't correspond to blackbody temperature?

No, but you're in the minority. Not everyone is a lighting nerd. Most only know the term "soft white" and they know what it looks like. All the other words, natural light, day light, full spectrum, etc....are there to fool the consumer.
CD