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Posted by sogentry (My Page) on
Wed, Feb 15, 12 at 10:08

I am replacing a fluorescent box in my kitchen with cans.

My box has four rods. They each give out about 3,000 lumens according to the packaging.

65 wat can light bulbs give off around 650 lumens.

So - if my box is giving off around 12,000 lumens how can I ever match the brightness? The box does have lenses of course, which may diffuse some amount of light, but still.

Anyone know some other mathematical way to figure out how many can lights I need?



Follow-Up Postings:

RE: Lumens

See the LED recessed can guide for kitchens. The formula used is a rough guide I used to estimate the number of cans.

Each fluorescent tube can output ~ 3k lumens when new.

However, when the tubes are enclosed in a recessed fixture/ box, the real fixture output is reduced by a significant amount just like the standard bulb in a recessed can fixture (which could have an actual output ~ 500 lumens vs the normal output of ~ 800 lumens of a naked bulb).

The net result is that my kitchen is better lit than before.

Here is a link that might be useful: recessed can guide for kitchens

RE: Lumens

Is LED really the way to go? They are so much more expensive and I have seen some wacky shadows with LED.

RE: Lumens

Not all LED lamps/ bulbs are created equal. Cree CR/LR series are (and will continue to be for quite some time) probably the best you can get today for recessed cans.

Considering the alternatives
1. Incandescents and halogens
2. CFL

Both suffer from the light in a can issue of requiring a high output in order for the recessed light to work well.

Incandescent lights are being phased out with halogens not too far behind.

CFL recessed can could actually be more expensive than LED - bulb + trim + can with integrated ballast vs LED lamp + can.

RE: Lumens CR6 type

The Cree CR/LR 4/6 series lamps are not the traditional bulbs that sold everywhere. The LEDs are arranged in a horizontal plane just below the lens all facing outwards.

Consequently the bulk of the light produced escapes the can.

A number of other manufacturers have adopted the same idea as evidenced by products like the HALO can lights, glimpseLED, disk and flat panel lights from many mainland Chinese companies ...

There are a number of reasons why Cree is currently the best such as
1. The output is not harsh.
2. The dimming range is good.
3. The color is nicely mixed. Not all the LEDs are of the same color.
4. The CRI is better than most.

RE: Lumens

I have 4" cans and tried every bulb I could find at HD to see if I could boost the output to something approaching 65W. Incandescent, halogen, fluorescent--none of them gave me what I missed from the 6" can over the sink I replaced.

Until I put in a CR4 (Ecosmart 575L). It has the brightness of a 65W bulb. It is beautiful and bright and not harsh at all. It's spendy at $50, but I think it's worth it. And great thanks to davidtay and the other good folks in the Lighting forum who held my hand through the entire process. :)

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