# Lighting Layout



## Sparky Joe (Apr 29, 2006)

Just a general question about common practice when laying out can lights.

I have 6 cans to install in a room that's 20x15. Would you just divide it all evenly and install them where they laid out? Which would put the corner cans 2' 6" feet off the one wall and and 3' 9" off the adjacent wall.

Or would put the corner cans say 4' away from eachof the 2 adjacent walls then space them evenly from there?

I could draw a picture if my wording isn't real clear.

Also as a rule of thumb, how far away from a corner would typically go to set a can before you thought it might not provide enough light in the corner?


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## fridaymean (Feb 17, 2006)

Sparky Joe said:


> I have 6 cans to install in a room that's 20x15. Would you just divide it all evenly and install them where they laid out? Which would put the corner cans 2' 6" feet off the one wall and and 3' 9" off the adjacent wall.
> 
> Also as a rule of thumb, how far away from a corner would typically go to set a can before you thought it might not provide enough light in the corner?


The 2'6" - 3' 9" for the corner cans sounds good to me, but you need to keep in mind what the room will be used for. Maybe 8 - 10 cans would be a good idea. Just depends on what the room is for.

_*IF*_ you want the corner to be bright, and the walls to be washed, don't go more than 2-3 feet away. 

Your original idea sounds like a good layout for 6 cans. Are they 6" or 4"?


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## Sparky Joe (Apr 29, 2006)

They're 6 inch, the room is going to be a living room in a basement, it also has 2 large windows, so there is plenty of light during the day.

The eight cans may not be a bad idea, maybe in like a domino pattern. 

I was just thinking of the equal distance out of the corner just because I like the way symmetry looks on a ceiling.


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## briselec (Feb 14, 2006)

I'd adjust the layout to make it symmetrical but that probably bothers us electricians a lot more than anyone else.


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## Sparky Joe (Apr 29, 2006)

A lot of people will say that no one notices the little things, and they probably don't outright, but I think they do some other way, sorta like a "vibe" I guess.


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## Mike Finley (Apr 28, 2004)

I would go to 8 cans (2 rows of 4) and space them long ways 4 feet apart and on the short wall 5 feet apart.


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## Sparky Joe (Apr 29, 2006)

Nice rule, thanks. 

I like the simple things that make life easier.


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## Mike Finley (Apr 28, 2004)

I changed my mind after looking at it on paper... edited my original thoughts


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## Sparky Joe (Apr 29, 2006)

Well the room is nearly square, 15x20, so I think 2x3 would look better than 2x4.


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## mdshunk (Mar 13, 2005)

A few words on lighting layout...
-The fixtures are always twice as far apart as the distance that they are from the wall

Consider that....
-the beam from a fixture will cast approximately the same distance left to right and front to back. 

Take a room that is 20 feet wide...
If you want 4 fixtures per row, divide 20 feet by *EIGHT* (twice the fixtures per row).
That gets you 2-1/2 feet. This is the distance of the fixture from the wall. Double that for the distance between fixtures, which will be 5 feet between fixtures. 
This will allow for equal light distribution without overlap.

Take a room that is 15 feet long...
If you want 3 fixtures along that length, divide 15 feet by *SIX*.
This gets you 2-1/2 feet again. This is again the distance from the wall, and double that for the distance between fixtures. 5 feet again.

Four fixtures per row along the 20' dimension and 3 fixtures per row along the 15 foot dimension will work wonderfully. Minor adjustments will be necessary to accommodate the framing, naturally, unless it's a drop ceiling.


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## PipeGuy (Oct 8, 2004)

mdshunk said:


> ...This will allow for equal light distribution without overlap.


How does the spacing preclude beam overlap without regard to the fixture's beam / baffle characteristic and its height from the floor?


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## Sparky Joe (Apr 29, 2006)

Thanks for the lighting 101, but I was more curious as to whether or not people like to keep equal spacing off of the 2 adjacent walls for the cans that are in the corners?


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## brian11973 (Apr 13, 2006)

In a 20' x 15' room, I would generally go with a 2 1/2' to 3' out, then space evenly. If this was more between 4' to 5' I would problaly go with the numbers. The difference between 2'6' and 3'9" at the corner, I think would be quite noticeable.

This brings another question. If the ceiling is smaller than the floor would you space on the floor or the ceiling? I did a "poker room"(15' x 20' w/ 5' soffit on the 20' side ) in a basement recently. The carpenter(builders #1) & I got in an auguement over this. I said the floor, the carpenter said ceiling. "it does not look symenticail"on the drop ceiling. I spaced them to the floor, so they were not in the center of the tile. The store shipped the wrong tile, so "we" got a second chance. I just let the " grumpy old man" have his way.


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> Thanks for the lighting 101, but I was more curious as to whether or not people like to keep equal spacing off of the 2 adjacent walls for the cans that are in the corners?


Sorry 'bout that Joe. I didn't intend to talk down to you. I was just offering some tidbits for carpenters and such who audit the electrical threads. 

With regard to spacing from adjacent walls, people have different ideas. The "you can't please everyone" idea comes into play, and whatever you choose on your own will always be wrong in the eyes of another. The word "design" is interchangable with "opinion". Everyone's got a different idea. The best case is to have someone else do the design or layout. This is my first choice. The second choice is to offer both layouts to the customer and let them choose. Then, if it doesn't please them, it's their fault (so to speak).


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## mdshunk (Mar 13, 2005)

PipeGuy said:


> How does the spacing preclude beam overlap without regard to the fixture's beam / baffle characteristic and its height from the floor?


Not the best choice of words on my part. I meant to say equal light distribution from side to side of the room. Obviously, photometric data should be taken to account on more critical lighting layouts with regard to MAXIMUM fixture spacing to avoid darker zones and with regard to MINIMUM lighting spacing to avoid brighter zones. Spacing the lights twice as far from each other as they are from the wall keeps the light that is cast (in footcandles) more EVEN from wall to wall.


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> Also as a rule of thumb, how far away from a corner would typically go to set a can before you thought it might not provide enough light in the corner?


I just noticed this part of the question.

There is no rule of thumb. It depends wholly on the ceiling height, fixture type, reflector type, and lamp selection. Every can manufacturer has photometric charts that will show the footcandle data (in graph form) for various trim and lamp selections for their cans. This information is not necessarily easy to get, but it is available from the manufacturer. 

How many footcandles are you looking for? For an 8' ceiling with 75 watt wide floods in the cans, I've done anything from 1' off the wall to 5' off the wall. It all depends on the desired maximum lighting level. Remember, better too close and too many cans than not enough. You can always install a dimmer. Whatever amount of cans you choose, make your layout as even as the framing permits, and you'll be golden. Well, maybe not "golden", but "okay". 

I hate lighting layout. That's what lighting designers are for. Lucky for me, one of our local lighting showrooms/supply houses has one on staff we can use for free or send the customer's to. Gives me someone to blame.


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## Sparky Joe (Apr 29, 2006)

Thanks Md for the lengthy reply(s) :thumbsup:


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> Thanks Md for the lengthy reply(s) :thumbsup:


Sorry. It's part of the syndrome for a fat-headed, know-it-all bastard.


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## ATS (Jun 28, 2005)

mdshunk said:


> Sorry 'bout that Joe. I didn't intend to talk down to you. I was just offering some tidbits for carpenters and such who audit the electrical threads.
> 
> With regard to spacing from adjacent walls, people have different ideas. The "you can't please everyone" idea comes into play, and whatever you choose on your own will always be wrong in the eyes of another. The word "design" is interchangable with "opinion". Everyone's got a different idea. The best case is to have someone else do the design or layout. This is my first choice. The second choice is to offer both layouts to the customer and let them choose. Then, if it doesn't please them, it's their fault (so to speak).



Well said MD. Rudd and other lighting manufacturers have lighting design engineers on staff to assist over the phone. I have used them a few times and have been satisfied with the results. Lighting design is a science and I would rather have a professional lay-out the fixtures when involved with a picky homeowner.


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## Sparky Joe (Apr 29, 2006)

I wonder if someone offers a lighting design course online?

I've always used common sense, or what I've seen before, but it'd be nice to have that extra tool in my pouches for the occasional 'picky' customer.


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