The attached photos show a different type of tower lighting called high-intensity lights – the big silver box I am working on in the pictures. (The red beacon you saw on the topic of the day yesterday is near my feet). Because of the limited beam width of these lights, one lightbox, called a flash head, has to be mounted on each leg of the tower at each light elevation. This means that if you have a 900′ tower, the FAA may dictate that you have a tier of lights at 300′, 600′, and at the top, 900′. This equates to nine total flash head units, one per leg at each of the three levels.
If you are looking at a tall tower in Google Earth and can count the levels of light boxes, or flash heads, you see, then you can tell fairly accurately how tall the tower is. High-intensity lights only flash in white mode, not the red mode, and they have three intensities of light-flashing: day mode, twilight mode, and night mode. Day mode is the brightest, twilight mode is in the middle, and night mode is the dimmest. The tower in the picture is WRC, Channel 4, in Washington, DC. If you look behind me in the picture, you can see the National Cathedral and the Washington Monument. As I am 5′ tall, you get a good idea of how large these light boxes, or flash heads, are compared to my height.
Also, you can see the nighttime, red incandescent beacon near my feet; this is the same type of light in the picture from yesterday. This particular tower has white day lights and red night lights on it because the red lights are less annoying to people at night than the white lights. Fun fact, when people take shots at tower lights with guns, they tend to shoot at white lights more frequently than red lights – or they tend to hit white lights more than red lights.
In the picture, I am replacing a xenon gas flash tube and the trigger transformer. Straight, xenon flash tubes cost about $300 each, and trigger transformers are about $125 each. When a tower owner has biannual maintenance done on high-intensity lighting systems, it usually costs about $11,000 in parts for the lighting system alone.
