How to Estimate Recessed Lighting

Walk through the room at various points in the day to assess the lighting needs. Determine the purpose of the recessed fixtures, which is often for accent lighting, task lighting or general illumination of the room.

Estimate how many recessed lights the circuit will handle in the room by adding the watts of the other items already on the circuit. Subtract the total from 1,440 for a 15-amp circuit or 1,920 for a 20-amp circuit, which are the maximum recommended wattages for each circuit size. For example, if you already have 800 watts on a 15-amp circuit, you have room for an additional 640 watts to divide between the recessed lights.

Identify the general area of the room where you want the recessed lighting. Decide if you want it around the perimeter of the entire room, near one fixture like the fireplace as an accent or over a portion of the room to create a brighter area for specific tasks like reading or preparing food.

Estimate roughly how far apart you plan to place the lights within the given area. As a general rule, each fixture will illuminate an area that is the same as the height of the ceiling when it reaches the floor. If you're looking for general room illumination, use an estimate of 6 to 12 feet apart. If you want more concentrated task lighting, use about 4 feet as your estimate. This helps you determine how many recessed fixtures you need to get the type of lighting you want.

Count the number of fixtures you want to add based on your initial layout design. Check the total wattage for that number of fixtures to ensure the circuit is able to handle it.