How to Determine How Much Recessed Lighting to Use

Measure the height of the ceiling, and ascertain the beam radius of the light bulb you will be using. The manufacturer can provide this information. A standard R40 floodlight casts a 60-degree beam of light. This means that in a room with an 8-foot ceiling, the light illuminates a 9-foot radius. The brightest illumination is 5 feet around the light.

Plan to position the lights about 5 to 6 feet apart for general lighting -- in a living room, for example. For areas where more light is required, such as a kitchen or a work room, plan to position the lights about 4 feet apart. When you're using recessed lighting to illuminate features such as artwork, simply position individual lights where they're needed.

Halve the planned distance between each light, and use this measurement to determine how far from the wall the lights should be placed. For example, if the lights are positioned 5 feet apart, the distance from the wall should be 30 inches. If the lights are positioned 5 feet apart and 5 feet from the walls, the room will be bright in the center and very dark around the edges. These distances are examples and do not have to be exact. If the room is not big enough for 5 feet between lights and a 30-inch distance from the walls, simply readjust the distances. In a 12-foot room, for example, position the lights 4 1/2 feet from each other.

Draw a simple scale drawing of the room where the recessed lighting will go, using an inch to represent a foot. Use your measurements to draw a border around the room to illustrate where the lights nearest the wall will be positioned, and measure the appropriate distance from these outer lights to ascertain the position of the lighting in the center of the room. Use a compass to illustrate the pool of light cast by each light. Experiment with different layouts until you are happy that the lighting is sufficient. Note that when you use a compass to illustrate the pool of light cast from each light, anywhere that the edges of the circles don't meet will be quite dark.