UL 96A:2007 pdf download – Installation Requirements for Lightning Protection Systems.
9.3.3 Each down conductor located in a runway, driveway, school playground, cattle yard, public walk, or other similar location shall be protected from mechanical damage or displacement. A conductor that runs through metal pipe or tubing shall be bonded to both ends of the pipe or tubing. The down conductor shall be protected for a minimum distance of 6 feet (1.8 m) above grade level. See 7.4.
9.3.4 A down conductor entering corrosive soil shall be protected from corrosion by a protective coating for a distance not less than 3 feet (914 mm) above grade level and for the entire length below grade level.
9.3.5 A down conductor shall not be routed within a downspout, or be wholly or parially supported by a downspout.
9.4 Interconnecting conductors
9.4.1 A main-sized conductor and bonding connector shall be used for interconnection of metallic water systems, steam or hot water heating systems, sprinkler pipes, electric service, telephone systems, antenna grounds, and other large grounded metallic masses.
9.4.2 A secondary bonding conductor shall not be smaller than 6 AWG (13.3 mm2) copper or equivalent.
10 Grounding
10.1 General
10.1.1 Each down conductor shall terminate in a grounding electrode.
10.1.2 Grounding electrode placement and configuration shall be any combination of the speifications outlined in this section.
10.1.3 Grounding electrodes shall be solid wire or strip, rod, solid plate, concrete-encased electrodes, ground ring electrode (loop conductor), or trenched electrode. The use of stranded cable as a grounding electrode shall be limited to a concrete encased electrode, ground ring electrode (loop conductor), or trenched electrode.
10.1.4 Each ground rod shall be not less than 1/2 inch (12.7 mm) in diameter and not less than 8 feet (2.4 m) long and shall be made of copper-clad steel, solid copper, stainless steel, or stainless steel clad.
10.1.5 Ground rod connections shall be made by main size clamp type connectors, by welding, or by brazing. Clamps shall make contact with the ground rod and conductor for a distance of not less than 1-1/2 inches (38 mm) measured parallel to the axis of the ground rod. Clamps shall be secured with at least two bolts or machine screws. Welded connections shall have a weld area at least two times the Cross-sectional area of the conductor.
10.1.6 Grounding electrodes shall be located at least 2 feet (610 mm) from the foundation wall. Ground rods shall extend vertically not less than 10 feet (3 m) into the earth. The earth shall be compacted and made tight against the full length of the conductor or grounding electrode. See Figure 10.1.
10.4 Common grounds
10.4.1 Each grounchng system shall be bonded together. This includes electnc, telephone, and antenna system grounds, metal well casings within 25 feet (7.6 m) of the protected structure, and underground metallic piping systems that enter the structure. These systems include water service, gas piping, underground conduits. underground liquefied petroleum gas piping systems, sprinkler systems, fuel oil lines, tank and tank lines, and similar piping systems.
10.4.2 II electric, telephone or other systems are grounded to a metallic water pipe, only one bonding connection to the water pipe system is required provided the water pipe is electrically continuous between all systems. If it is not electrically continuous because of the use of plastic pipe sections or for other reasons, the nonconductive sections shall be bridged with main-sized conductors, or the bonding connections shall be made at a point where there is electrical continuity.
Exception: Common bonding of other grounded services may be achieved if interconnected wth the water piping system or bonding buss as long as the water piprngbonding buss are bonded with a full size lightning conductor. Connections between the grounded services and their water pipe ground connection or bonding buss needs only to be sized as recommended by their own grounding requirements, for example, the National Electrical Code, ANSI..’NFPA 70.
10.4.3 Main-sized conductors and connectors shall be used for common ground connections.
10.5 Concrete-encased electrodes
10.5.1 Concrete-encased electrodes shall be used only in new construction and are to be utilized m addition to other grounding methods (e.g. ground rods, ground plates. and ground rings) as specified in 10.1.