Lightning Protection System around Communication System Cables

[deb4523]

If you have multiple antennas (with attached cables) installed on the edge of roofline that needs a lightning protection system, how do you meet the requirements in NEC 820.44 (E)(3) and NEC 830.44(G)(3) while meeting the requirement in NFPA 780 section 4.7.2.1? The antennas can not be relocated. The NEC requirements both begin with "Where practicable", making it a suggestion, not a requirement?

Side flash distance calculated from NFPA 780 section 7.6.5.2 is about 1.5 feet. So I should be ok if we make the lightning conductor distance from the roofline a minimum of 1.5 feet and a max of 2 feet, right?

I've been told that the communications systems are fully protected for surges, etc. NFPA 780 section 4.17 states that the antennas must be connected to the protection system using conductors, but this requirement also seems to conflict with the requirements in the above stated NEC codes. Thoughts? The antennas are taller than any air terminals would be. Any other considerations for the antennas and the cables that are attached to them?

There is metal conduit installed on the exterior of the building or lighting circuits that originate inside the building. Do I tie these to the protection system, or would that cause problems inside?

I know there are a lot of questions here. Thanks for your help!

 

[deb4523]

Notes:
*NEC 820.44 (E)(3): Where practicable, a separation of at least 1.8 m (6 ft) shall be maintained between any coaxial cable and lightning conductors.
*NEC 830.44 (G)(3):Where Practicible, a separation of at least 1.8 m (6 ft) shall be maintained between any network-powered broadband communications cable and lightning conductors.
*NFPA 780 4.7.2.1: As shown in figure 4.7.2.1, the distance from strike termination devices to ridge ends on pitched roofs or to edges and outside corners of flat or gently sloping roofs shall not exceed 2 ft.
*Side flash distance should have been referenced to NFPA 780 4.6.5.2, not 7.6.5.2.
*NFPA 780 4.17: Metal Antenna Masts and Supports. Metal antenna masts or supports located on a protected structure shall be connected to the lightning protection system using main-size conductors and listed fittings unless they are within a zone of protection. **Yes, I know this refers to masts, not the antenna itself. But if the antenna is on the mast with the cable running on the mast to the antenna, it still seems like it would be a problem...