MANUFACTURER'S LITERATURE

The performance specifications of each model, type, and size of luminaire are provided with the fixture or obtained from the manufacturer's ordering catalog. A working knowledge of this information will assist you in selecting and installing the correct floodlight to accomplish the job. Figure 1-25 shows the manufacturer's literature provided with a General Electric, 250- to 1,000-watt, LucaloxR, HLX PowerfloodR luminaire.

ISOFOOTCANDLE DIAGRAMS

The isofootcandle diagrams show what the light level will be at any given point. The dimensions for the diagram are based on the mounting height (MH) of the floodlight. The aiming point () is also based on the mounting height. Figure 1-25 provides a diagram for mounting heights of MH 0.5, MH 1, and MH 2.

The grid pattern is also based on the mounting height. The grid line values left and right give the distance to either side of the floodlight. The values up the side show the distance in line with the aiming direction of the floodlight. The number 3, for instance, represents 3 40, or 120, feet from a 40-foot mounting height.

Each isofootcandle line shows where the footcandle level is the same. These lines are identified by a letter, which is used with the initial footcandle (fc) table. The footcandle values between isofootcandle lines do not change more than 2 to 1. This makes it possible to approximate the level between lines.

The initial footcandle table gives the footcandle value for each isofootcandle curve at a specific mounting height. The values for each

Figure 1-25.\Floodlight manufacturer's literature.

letter are the same on each set of curves. This makes it possible to compare diagrams directly and interpolate between curves for different aiming distances.

The mounting heights given in the table are representative of the wattage and beam pattern associated with the floodlight. To convert to other mounting heights, use the following formula:

For example, a 5-footcandle level at 50 feet (isofootcandle curve F) would have a value of 4.13 at a 55-foot mounting height.

In figure 1-25 (aiming point MH 2), the floodlight is aimed a distance of two mounting heights away from a point on the ground directly below the floodlight. This would be 80 feet for a 40-foot mounting height.

UTILIZATION GRAPH

The luminaire utilization graph gives the percentage of the initial lamp lumens that fall into the area being lighted. Knowing this, you can easily determine the average lumens per square foot, or footcandles.

The number beside each curve identifies the aiming point so that the utilization curve can be identified with the associated isofootcandle diagrams. In the example, for instance, the floodlight aimed two mounting heights away from the pole would have a utilization of 35 percent if it were lighting an area three mounting heights wide. The same floodlight aimed at one mounting height away from the pole would have a utilization of 45 percent for the same area.