The law does not stipulate wattage for fixture, fixture types, lamp types, or even a set number of foot candles.
This is left to the lighting designer to determine, as the intent of the law is what matters here. The point is to place the flag in its own special field of light so that it can be scene clearly regardless of its surroundings or any other types of lighting in its immediate area.
In communities that still permit up lighting, most flag lighting is done with fixtures that shine up the pole and illuminate the flag. There are basically only two types of fixtures that do this: inground and above ground fixtures. Both are highly effective, depending on the application and the environment.
In ground fixtures for flag lighting go into the ground. Because they are buried below the surface, the lamps are shielded from visibility. The advantage to using inground fixtures is they eliminate glare. The degree of illumination is determined by fixture aim.
In ground lights can be purchased with halogen, LED, or HID lamps.
Above ground flag lighting fixtures are mounted at key locations at the base of the flag. They can be affixed to conduits or junction boxes and aimed directly up at the flag. These fixtures have much higher wattages and are only available with HID lamps. They are essentially a form of floodlight that shines a bright beam up the pole at an angle.
The width and intensity of the beam distribution depend on the wattage of the lamp and the aiming of the fixture.
Selecting the right type of lamp is based upon the size of the flag, the height of the flagpole, and the amount of ambient light present in the immediate surrounding environment.
For example, a flag at a car dealership flying on a 30 foot pole is going to be illuminated already by the dealership lights. In order to spotlight such an object, HID above ground lights would be needed to put additional illumination on the flag and make it stand out from its surroundings.
Another example would be lighting a flag in front of a public school. Depending on the height of the pole and the amount of parking lot lighting, either metal halide inground fixtures or HID above ground fixtures would be needed. The final choice should be made after a photometric analysis of the school parking lot and a determination as to which lamp types will best meet the needs of facility.
LED flag lights, while still striving to catch up with other types of lighting, are great ways to save on power and promote a greener environment in certain locations. Many small businesses, subdivision neighborhood associations, and small suburban parks fly flags on poles that that stand less than 15 feet in height.
In these environments, it is often very dark around the flagpole. LED lights are more than sufficient to light flags at night here because there is no ambient light from parking lots or HID outdoor flood lights.
It is very important that those looking into flag lighting also be made aware that many communities are now banning up lighting altogether. In this event, neither in ground nor above ground fixtures are permitted any longer. A down lighting alternative must be worked in order to comply with both municipal dark sky laws and Federal laws on appropriate illumination of American flags.