The surveillance camera, which was installed after the original lightning protection system installation, is unprotected from a lightning strike. An air terminal is required for the camera since the metal arm does not have a metal thickness of greater than 3/16 of an inch. Also the camera arm lacks a bond to the lightning protection system to prevent side flash.
Per NFPA 780-2014; paragraph 188.8.131.52 The tip of an air terminal shall be not less than 10 in. (254 mm) above the object or area it is to protect. Paragraph 184.108.40.206 . Metal parts, of a structure that are exposed to direct lightning flashes and that have a metal thickness of 3/16 in. (4.8 mm) or greater shall only require connection to the lightning protection system in accordance with Section 4.8.
Installation of a 5/8 x 18” aluminum air terminal with a 2” aluminum horizontal air terminal clamp base. The air terminal and base shall be installed at the outer portion of the camera arm. A “dead-end” single run conductor shall be spliced to the main run conductor located on the parapet coping with a two-bolt parallel cable splicer.
NFPA 780-2014 paragraph 4.9.2 Dead Ends. A “dead ended” main conductor shall be permitted between a single strike termination device or connector fitting and a main conductor run under the following conditions: (2) At a main protected roof level, where the horizontal portion of the dead-end conductor is not more than 8ft (2.4 m) in total length.
Apparently, during a repair, the air terminal was removed from the coping and is being positioned by the stiffness of the aluminum conductor. No adhesive was present to indicate that the base was re-adhered to the coping after the repairs.
Per NFPA 780-2014 paragraph 220.127.116.11.1 Air terminals shall be secured against overturning or displacement by one of the following methods:
- Attachment to the object to be protected
- Braces that are permanently and rigidly attached to the structure.
Remove all existing adhesive from the bottom of the air terminal base, or replace the air terminal base, and adhere the base with an approved roofing adhesive. Confirm the distance between the adjacent air terminals does not exceed twenty feet (20’-0”).
The lightning protection cable routed to the through roof cable connector is creating a “U” pocket increasing impedance on the flow of a stroke charge.
Per NFPA 780-2014; paragraph 18.104.22.168 Conductors shall maintain a horizontal or downward coursing free from “U” or ”V” (down and up) pockets.
The lightning protection conductor shall be routed from the roof surface to the through roof cable connector at a slope not greater than 3” per foot (3/12).
NFPA 780-2014; paragraph 22.214.171.124 Conductors shall be permitted to he coursed through air without support for a distance of 3 ft (0.9 m) or less. NFPA 780-2014; paragraph 4.9 Conductors. Main conductors shall interconnect all strike termination devices and shall form two or in or paths from each strike termination device downward, horizontally, or rising at no more than 1/4 slope to connections with grounding electrodes.