Light
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Ricorocks
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- Mar 30, 2014
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Here it is: Formula for shop lighting:
How to Figure Spacing for Fluorescent Fixtures | eHow
Playing with the numbers I calculated my space needs 9 fixtures.
Each T8 = 5600 lumens.
Currently I have 3 fixtures. 6 more fixtures seems allot
How to Figure Spacing for Fluorescent Fixtures | eHow
Playing with the numbers I calculated my space needs 9 fixtures.
Each T8 = 5600 lumens.
Currently I have 3 fixtures. 6 more fixtures seems allot
Ricorocks
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Example:
Lighting is a very important subject for work shops. Poor lighting can hinder your productivty, cause eye strain, and probably most importantly ,can compromise your safety.
The industry standard for general lighting in a room is 70 foot candles per square foot.
To determine how many fluorescent ceiling fixtures you need, a formula is needed to determine the number of lumens needed.
A couple of pieces of information are needed for the formula.
The square footage of the shop. Length X Width .
The Lumens per fixture. A typical 4ft. 40 watt bulb has 3150 lumens of lighting ability.
The co-efficient of usage. Represented by the constant .65
Light loss factor. Represented by the constant .75
For this example we will use a shop that measures 16x24 feet.
Sq. Ft. = 16x24= 384 sq.ft.
Multiply your sq. ft. (384) by 70 lumens. Since 70 lumens are needed for every sq. ft., this will give you a preliminary number for total lumens.
384 x 70= 26880 lumens . But we aren't done yet !
That is the minimum amount of lumens needed .
There is a light loss factor (.75) and a co-efficient of utilization (.65)
that are added together .
.75+.65 = 1.40
Now we can multiply the minimum amount calculated from above (26880) * (1.40) = 37,632 (almost there.)
37,632 lumens is then added to the minimum lumens needed to obtain
37,632 lumens + 26,880 lumens = 64,512 lumens.
Now we know how much ceiling lighting in lumens are needed. Here is how you determine how many fixtures you need for this 16x24 ft. shop.
As stated above a typical 4 ft. 40 watt bulb has 3150 lumens so a two bulb fixture has 2 x 3150 = 6300 lumens.
So finally we are down to just dividing the lumens of a typical 4 ft fixture (6300) into the total lumens needed (64,512) to light the shop to industry standards.
64,512/6300 = 10.24
So 10.24 four ft. fixtures with (2) 40 watt bulbs are needed to light the shop.
Fixtures Needed to light a 16x24 ft. shop = 10.24 fixtures.
In this case you could likely round down to 10 fixtures and be good.
This method obviously cannot take into account every shop configuration. Some tools will cast shadows and create areas that may not be illuminated as well as they should be. In those cases supplemental lighting can be added.
Also of interest, the height of ceiling isn't considered in this method. So I'm not sure how the industry derived this formula. I'm sure each shop will require some tweeking but this method should at least give some kind of starting point.
Seems a little time consuming but would be interesting to see how many of us are under or over industry standards for the lighting in
our shops.
Thanks for taking the time and work safe.
Last edited by against_the_grain; 03-29-2013 at 02:45 AM.
Lighting is a very important subject for work shops. Poor lighting can hinder your productivty, cause eye strain, and probably most importantly ,can compromise your safety.
The industry standard for general lighting in a room is 70 foot candles per square foot.
To determine how many fluorescent ceiling fixtures you need, a formula is needed to determine the number of lumens needed.
A couple of pieces of information are needed for the formula.
The square footage of the shop. Length X Width .
The Lumens per fixture. A typical 4ft. 40 watt bulb has 3150 lumens of lighting ability.
The co-efficient of usage. Represented by the constant .65
Light loss factor. Represented by the constant .75
For this example we will use a shop that measures 16x24 feet.
Sq. Ft. = 16x24= 384 sq.ft.
Multiply your sq. ft. (384) by 70 lumens. Since 70 lumens are needed for every sq. ft., this will give you a preliminary number for total lumens.
384 x 70= 26880 lumens . But we aren't done yet !
That is the minimum amount of lumens needed .
There is a light loss factor (.75) and a co-efficient of utilization (.65)
that are added together .
.75+.65 = 1.40
Now we can multiply the minimum amount calculated from above (26880) * (1.40) = 37,632 (almost there.)
37,632 lumens is then added to the minimum lumens needed to obtain
37,632 lumens + 26,880 lumens = 64,512 lumens.
Now we know how much ceiling lighting in lumens are needed. Here is how you determine how many fixtures you need for this 16x24 ft. shop.
As stated above a typical 4 ft. 40 watt bulb has 3150 lumens so a two bulb fixture has 2 x 3150 = 6300 lumens.
So finally we are down to just dividing the lumens of a typical 4 ft fixture (6300) into the total lumens needed (64,512) to light the shop to industry standards.
64,512/6300 = 10.24
So 10.24 four ft. fixtures with (2) 40 watt bulbs are needed to light the shop.
Fixtures Needed to light a 16x24 ft. shop = 10.24 fixtures.
In this case you could likely round down to 10 fixtures and be good.
This method obviously cannot take into account every shop configuration. Some tools will cast shadows and create areas that may not be illuminated as well as they should be. In those cases supplemental lighting can be added.
Also of interest, the height of ceiling isn't considered in this method. So I'm not sure how the industry derived this formula. I'm sure each shop will require some tweeking but this method should at least give some kind of starting point.
Seems a little time consuming but would be interesting to see how many of us are under or over industry standards for the lighting in
our shops.
Thanks for taking the time and work safe.
Last edited by against_the_grain; 03-29-2013 at 02:45 AM.
dcjredline
New member
- Mar 26, 2012
- 3,340
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I have 9 just for my detail area of my 28x30 shop. I use less than half of the 30 for that area
