# Light levels

Discussion in 'General Electronics Chat' started by inwo, Sep 6, 2014.

1. ### inwo Thread Starter Well-Known Member

Nov 7, 2013
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Rather than hijacking a thread where #12 posted about rpm cube rule.............

Does anyone know how much to increase lumen output to double light level?

4 times? Square rule. Cube?

Ignore the details if possible. Just ball park.

Over head light (high bay) outputs 120 degree pattern.

For example. If I have a 5,000 lm source now and want to double the light level in the area covered by the 120 degree pattern.

More questions to follow if there's an expert here.

Jul 18, 2013
10,851
2,521
Not answering your question, but one thing I found was that also light technology is important, depending on what the facility does, locally a recent change by a bus manufacturer to increase the lighting in their wire stripping and harness facility, resulted in perceived colour change in some wire colour's to an entirely mis-read of the true colour.
Max.

3. ### inwo Thread Starter Well-Known Member

Nov 7, 2013
2,435
315
Haven't found much yet.

Near as I can tell it's 1 to 1. lamp lumen to lux at a given distance.

Inverse square with distance.

So if I double lumens I double lux at the same point.

If true it will make life easier.

4. ### #12 Expert

Nov 30, 2010
16,703
7,336
I think you're right on both constants.
Where did I learn this stuff?
GE lighting catalog? No.
Physics 101? No
Ack! Senior moment!

inwo likes this.

Apr 5, 2008
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6. ### wayneh Expert

Sep 9, 2010
12,388
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Sounds good to me. Lumens is total output, lux is just lumens per area, and area increases with the square of distance. Once distance is fixed, double lumens gives double lux.

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7. ### NorthGuy Active Member

Jun 28, 2014
611
121
And if you build a reflector, you'll also add the light that would otherwise go to the other side.

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8. ### inwo Thread Starter Well-Known Member

Nov 7, 2013
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Sounds promising.

If I use a 120 degree led down-light @ twice the lumens, I could get 6 times the light level. Maybe 4 or five considering reflected light from the original 360 degree bulb.

Calculator: http://www.kurtzon.com/Calculator

Don't know if the CU can be over 1 if all light is concentrated.

Edit
calc. lets me input a 2 or three with expected results. Don't know if it's valid. ??