When deciding how to place recessed lighting, you need to consider a few different factors. First, what is the lighting for? Is it a living room you are remodeling, and will there be artwork to illuminate? Or is it a shop area where you will want the maximum light efficiently possible? These questions will help you figure out where and how much lighting you will need.
In addition, you may have to consider limitations caused by what is in your ceiling, such as support beams or ventilation ducts.
The purpose of the lighting is the first and most important factor. If you are lighting a work area, you will want as much light as you can get, spread evenly throughout the room to cut down on shadows.
For a living or dining area, you may want to be able to control the lighting to suit the event, and may also want to showcase artwork, which will mean lights placed near to the walls. If your room is painted in light tones, you will need less lighting than a room painted a rich hue with dark leather furniture, such a den or library.
Rules of Thumb
The basic rules for placement is take the height of your ceiling, divide it by two, and space the lights at that distance. For example, if your ceiling is 10 feet high, the lights should be placed 5 feet apart in a grid.
The lower the ceiling, the more lights you need because the throw of the light will be more focused due to the shorter distance. If you are working with lower ceilings, such as in basement where a dropped ceiling may only be 6 or 7 feet high, you can probably get away with slightly more distant spacing, especially if the recessed lights throw at a broad angle.
The rule of thumb for lighting art is to place the lights 1 to 2 feet from the wall. The higher the artwork is hung, the closer to the wall you will need to place the lights to illuminate it fully.
You may find obstructions within the ceiling that you need to work around, such as beams, vents or similar impediments. In addition, there may be particular spots in the room that you want to accent, such as a sculpture.
Drawing up a scaled map (1 inch=1 foot is a common scale) of the ceiling and marking the blocked areas and points of your accent lighting can be a help. You can then grid the light around the obstructions and accent lights for even distribution.