If you are seeking to use fluorescent floodlights to illuminate your client’s building with a uniform, scallop foot candle spread, RLLD Commercial Lighting strongly recommends that you closely follow the guidelines enumerated in this article. If you need to vary the lighting levels, this can be accomplished by changing lamp wattage without changing out the fixtures.
Establish the Proper Aiming Points
In order to achieve a uniform distribution of light from the top of the building on down to the bottom, aim the fluorescent floodlights two thirds up the vertical surface. For example, if the wall is 25 feet high, aim the fixtures toward a point 17 feet up from the ground.
What to do when you encounter limited setback.
Setback is frequently limited. Work with the amount of space you have. Lighting standards call for the minimum setback distance to be one-quarter the height of the wall. If you have more room to work, install the fixtures at the same distance from the wall as your aiming point is from the bottom of the wall. Using our example above, that would be 17 feet back from the wall.
Regardless of setback, spacing should still be twice the setback.
In order to achieve optimum uniformity of luminance, space fluorescent floodlights at a distance that is equal to two times the distance of the setback. In our current example, fixtures setback 17 feet from the wall should be spaced 34 feet apart. This will cause the light beams to overlap one another, resulting in a uniform spread. If your client is more concerned with cost than with uniformity, however, you can purchase fewer fixtures and vary spacing up to five times the amount of setback distance.
Explain to your client the advantages that fluorescent floodlights offer over inground uplights.
Many facilities managers will request uplights because they are so easy to conceal and pose no obtrusive distraction into the scene. However, they are best used as sign lights, monument lights, or decorative landscape lights. Because they are located so close to the subject they are lighting and cast a near vertical beam upward, you cannot achieve the same uniformity in light spread as you can with fluorescent floodlights.
Save time with a photometric design from RLLD Commercial Lighting.
The example we provided above assumes there is a more or less symmetrical building to light and sufficient acreage on a lot to allow for appropriate setback. As you have no doubt seen through your own experience as an electrical contractor, these ideal hypotheticals often end with the back cover of the technical manual. Real world scenarios are much more complex and demanding, often calling for innovative design and installation strategies that will take too many billable hours to compute.
This is cost you do not want to pass on to your client in addition to the cost of procurement and installation of the actual fixtures.
Instead, let our lighting design team calculate the setback and spacing that will be ideal for your client’s building. If your client has a multi-building site, such a design is a crucial timesaver and will ensure that you get the right number of fixtures and the right foot candle measurements regardless of the symmetry of the individual buildings, their relationship to one another, and the amount of surrounding landscape you have to work with.
The design we provide you will be a 3D model that you can show to our client that will depict the location and beam spreads of the fluorescent lighting fixtures we recommend. The cost of the design photometric will be deducted from your final invoice total at the time you purchase the equipment from us.