Medium Intensity Lighting
FAA Type L-865
A medium intensity white lighting system utilizes a single flashhead for daytime and nighttime marking and is usually approved for use by the FAA for non-urban settings. It is used on structures ranging from 200' to 500', and is not recommended for use on towers less than 200’ when obstruction lighting is required. The flashhead is powered and controlled by a power supply that can be mounted remotely at the base of the structure. Most power converters constantly monitor the operation of the system and provide alarm contact closure upon any failure. By use of a photocell the omni-directional lighting system will automatically switch between day (20,000 candelas) to night (2,000 candelas) intensities. Although all medium intensity lighting systems must meet FAA certification guidelines, not all systems offer the same product benefits.
Height includes all appurtenances
The overall height of the structure including all appurtenances such as rods, antennas, obstruction lights, etc., determines the number of light levels. On a structure 200’ to 350’ in height (D-1 System) only one flashhead is required at the top of the tower. For structures 351’ to 500’ (D-2 System) the FAA will require a flashhead at the top of the tower and two at the structure’s mid-point level and not below the 200’ level, unless otherwise requested in the FAA’s aeronautical study.
No obstruction greater than 7/8” can be in the path of the flashhead’s horizontal beam.
For additional information regarding FAA marking and lighting standards for medium intensity lighting requirements in excess of 500’, you can review FAA AC-70/7460-1K at: Obstruction Marking and Lighting (2.96 MB). For Federal obstruction lighting and marking questions most commonly asked, click here.
The average list price of a single medium intensity lighting D-1 System is $3,300. This does not include freight, installation or the cost of the power cable from the flashhead unit to the power converter at the base of the tower. The average list price for power cable is $1.60 per ft. The average list price for a D-2 System which includes three flashhead units, a master power converter and two slaves is $9,600. This does not include freight, installation or the cost of the power cable from the flashhead units to the power converters. Include the three runs of your power cable at a list price of $1.60 per ft.
Although some residents believe that medium intensity lighting is intrusive, the FAA in 1966 required all manufacturers to provide a product that allowed a maximum of 75 candelas of stray light at -10 degrees horizontal below the beacon. Equal to what you would see from a 60W light bulb, the new standard provides a neighbor- friendly system. Today, many Fresnel lenses are made of molded plastic, creating an almost flawless surface with no scatter light. For years, however, the red incandescent beacon was the only option for nighttime obstruction warning, and residents became accustomed to seeing red lights in the night sky. Gaining popularity in the community is the dual lighting system. It utilizes a medium intensity white strobe during the dayand a red beacon or strobe for night.
We recommend that you contact our valued lighting manufacturers and distributors for your site-specific requirements.