ozak

I asked the electrical lighting shopkeeper why the 30W/7000K light is brighter than the 24W/7000K light.? He answered that there are more LED bulbs inside the 30W/7000K light = consumes more electricity but brighter. It's not because it is less power efficient in terms of Lumen per Watt.

Please have a look at the individual bulbs(its number can vary) inside the Clear-type LED T8 tube lights at this link .......
https://www.aliexpress.com/item/32797464152.html
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Your Philips 2100 Lumen light is likely brighter but my Wurui 7000K light is whiter.

Also, my Wurui 24W light has more LED bulbs inside = this may mean that my Wurui light is overall brighter and whiter than your Philips light.

I could have gone for the even brighter 30W/7000K light but preferred not to consume more electricity since the 24W/7000K light was already bright enough for my living room. Similarly, no point putting the same bright light in my small 7' X 5' bathroom = I used the 2-feet 11W/6500K light.

It still boils down to personal preference.
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6500k,7000k or 3000k is a light color temperature. 3000k is a more yellowish white. While 6500k is more white. Some manufacturing keep it short as warm light and day light.

Lumens is brightness. 2100L is more brighter than 1700L. It is a correct measurement of the light brightness.

Watt is a power of the electrical appliance. The higher the watt, the more consumption of the eletricity.

From this, watt doesn't tell you how bright the light. It only tell you the light power consumption.

So how efficiency is the light?

A 24w led light produce 1920 Lumens , 1920/24 = 80L per 1 watt. It's mean the light use 1W of power consumption to produce 80L of light brightness.

Take another Philip T8 led. 20W produce 2100Lumens, 2100/20 = 105L perwatt.

That means, Philip Led T8 is more efficiency and save more as a LED light.

People always confuse between color of the light and brightness. Always read the spec of lumens = brightness and K = temperature color of the light.

You will be able to tell how bright is to step back far from the light. The overall shine the area will be lesser or further.

Having too high k light 7000k will not give higher brightness. It's the color that make you "feel" bright. Too high K will cause glare and also cause your eye have difficult look in the dark when getting age.

brighter and whiteer....but the area covered better than 2100 lumem?

thanks ..

can i say that 2100 lumem the light shine to the area will be more widen then the 1920 lumem light ?
thanks ..

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When choosing an LED frosted tube light, I think we need to look at all 3 ratings of Wattage(= number of LED bulbs inside), Lumen(= brightness) and Kelvin(= whiteness).

To light up a large room at night, we should go for high Wattage, Lumen and Kelvin. Which high combination of W/L/K is up to personal preference. In my case, I prefer 24W/1920L/7000K lights for my living room. You prefer 20W/2100L/6500K for your porch. Others may prefer different highness combination.
...... Of course, it is not advisable to go for a low W/L/K combination for a large room/area, eg avoid 18W/1600L/3000K lights.
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When choosing an LED frosted tube light, I think we need to look at all 3 ratings of Wattage(= number of LED bulbs inside), Lumen(= brightness) and Kelvin(= whiteness).

To light up a large room at night, we should go for high Wattage, Lumen and Kelvin. Which high combination of W/L/K is up to personal preference. In my case, I prefer 24W/1920L/7000K lights for my living room. You prefer 20W/2100L/6500K for your porch. Others may prefer different highness combination.
...... Of course, it is not advisable to go for a low W/L/K combination for a large room/area, eg avoid 18W/1600L/3000K lights.
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Yup. it will be more widen and further. But the small number different will not give you much judge. But will have different when few yrs time usage.

When I install the philip 20W led and compare the old Fluro, I can see the old fluro shine further or cover wider area. Old T8 fluro have a higher lumens.

Even the Philip LED look whiter, it doesn't cover wider area.

You have to step back further where your eye can see the whole area in order to compare the brightness. Or if you have the light/Lumens meter to check.

Yup. it will be more widen and further. But the small number different will not give you much judge. But will have different when few yrs time usage.

When I install the philip 20W led and compare the old Fluro, I can see the old fluro shine further or cover wider area. Old T8 fluro have a higher lumens.

Even the Philip LED look whiter, it doesn't cover wider area.

You have to step back further where your eye can see the whole area in order to compare the brightness. Or if you have the light/Lumens meter to check.

Fluorescent lights are omnidirectional. Omnidirectional lights produce light in 360 degrees. This is a large system inefficiency because at least half of the light needs to be reflected and redirected to the desired area being illuminated. The need for reflection and redirection of light means that the output is much less efficient for omnidirectional lights due to losses than it would be for the same light if it were directional by its nature. It also means that more accessory parts are required in the light fixture itself in order to reflect or focus the luminous output of the bulb (thus increasing unit costs).

LEDs are extremely energy efficient relative to every other commercially available lighting technology. There are several reasons for this to include the fact they waste very little energy in the form of infrared radiation (much different than most conventional lights to include fluorescent lights), and they emit light directionally (over 180 degrees versus 360 degrees which means there are far fewer losses from the need to redirect or reflect light).

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https://www.stouchlighting.com/blog/fluores...t-vs-led-vs-cfl

For my large living room(22' X 75' link house), I have to install two 4-feet LED T8 24W/7000K/1920L frosted tube lights to cover it with enough brightness and whiteness. One light, no matter the highest W/K/L, whether LED or fluorescent, is not enough to cover the whole of my living room.
....... For my bedroom, one such light is enough to cover it with sufficient brightness and whiteness. For my small bathroom, one 2-feet LED T8 11W/6500K frosted tube light is enough.
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ozak

The Chinese coffee-shops that I often go to, all use bright/white/high Wattage/Lumen/Kelvin 4-feet LED T8 frosted tube lights, ie not low W/L/3500K lights.

7000K lights are not glaring as long as you do not look directly at them for more than a second or 2. I think the 3500K or below yellow-white or not-so-bright/white lights are more for a dimly-lit romantic setting.

Previously, I changed all my 18W 4-feet fluoroscent tube lights in my house to 36W ones for more brightness. The 18W ones were installed by an electrical contractor many years ago.
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been using Philip 1year plus ~2years ...
now in market the higher k is 7000k ?

thanks ..

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https://www.stouchlighting.com/blog/fluores...t-vs-led-vs-cfl

For my large living room(22' X 75' link house), I have to install two 4-feet LED T8 24W/7000K/1920L frosted tube lights to cover it with enough brightness and whiteness. One light, no matter the highest W/K/L, whether LED or fluorescent, is not enough to cover the whole of my living room.
....... For my bedroom, one such light is enough to cover it with sufficient brightness and whiteness. For my small bathroom, one 2-feet LED T8 11W/6500K frosted tube light is enough.
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yes ..for your case yes ...

my case is to find higher lumem which is over 2100k with less than 30W for to cover widen area outside my house ...
initially thinking your 24W 7000k will covered widen ...but its not ..caused lumem still less than my current Philip...

I not sure what age are you. But have you notice that, older people have problem seeing in dark or at night ?

They often complain that the place is too dark. While the young said it's fine?

That is the problem when you constantly expose to light too bright and glare.

Especially now 6500k is not enough for people. That is some alarming problem coming.

What happen if people chasing till 7500k or 8000k ?

3500k or yellow light is not dimly lit. Yellow light can be very bright if the lumens is high. Again don't confuse between bright and color or Lumens and kelvin.

Have you use before downlight bulb CFL which is 3500k 1600L ? If you use before, you know how bright that yellow CFL bulb.  

Do you know light color have wavelenght? Why street light or your car head light is yellow? Why all the car brand don't put a 7000k head light?

Why you want a higher lumens to cover outside house?

If you want to do some work outside your house, try install 2 kind of light. Switch it off if you done your work.

Left the lower lumens light ON.

That also help reduces the bill.

Cause you are not working every day or the whole night.

120VAC? How?

Brought in US. Use in US home.