FROM THE LIGHTNING PROTECTION INSTITUTE PROTECTION CODE Trees do not afford protection from lightning to nearby buildings, and in many instances they should be protected in view of their particular value to the owner. It is recommended that trees which have trunks located within 10 feet of a protected building, and the branches of which extend to a height above a building, be equipped with lightning protection, not only to protect the tree, but also to avoid the possibility of lightning striking the tree and side flashing or grounding to the nearby structure.
STANDARD TREE CONDUCTOR CABLE shall by used on the main trunk of the tree and for all ground connections. The ordinary tree with trunk up to 3 feet in diameter requires one standard conductor, extending from the highest accessible part of the tree, or from the main junction of branches, along the main trunk to the ground connections. Trees with trunks exceeding 3 feet in diameter, with long and wide spread branches, should be provided with 2 standard down conductors placed on opposite sides of the trunk.
MINITURE TREE CONDUCTOR CABLE may be used for branch runs, and shall extend from accessible heights of 3 or more of the main branches down to the main trunk and a connection made to the standard conductor with a CABLE SPLICE (Large to small type). Connections made from Standard to Standard Cable shall be made with a Cable Splice (Large to Large type).
POINTS, (Standard Tree Points & Miniature Tree Points) designed expecially for tree installations shall be attached to the extreme upper ends of both standard and miniature conductors and shall be securely anchored to the tree for permanency and complete efficiency. CONDUCTOR ATTACHMENT DRIVE FASTENERS shall be used to securely attach the conductor to the tree in such a way as to allow slack for continued growth of the tree and for swaying in the wind.
GROUNDING: Properly made grundings are essential to the effective functioning of tree lightning protection systems. The procedure for grounding will depend upon the character of the soil and the surrounding conditions. It should be kept in mind that usually the underground spread of the root system is equal in area to the spread of the branches above ground.
Extend the Standard conductor down the trunk and out and away from the base of the tree in a shallow trench (approximately 12″ in depth). This conductor shall terminate at a depth ground extending down to permanent moisture. A 1/2″ x 8′ COPPER CLAD GROUND ROD AND STANDARD BRONZE GROUND ROD CLAMP provide effective grounding in normal soil conditions.
The fork type ground system is most effective and is often practical to use, due to soil conditions, nearness of trees to buildings, concrete, sidewalks, property lines, etc. The standard down conductor is placed in a shallow trench and extended out from the base of the tree from 12 to 15 feet or even further. At the end of this conductor a depth ground to permanent moisture is added. Standard conductors are attached to the main conductor with a FORK GROUND CONNECTOR and placed in a shallow trenches forming a fork. Large trees require additional depth grounds.
When it is impossible to drive depth grounds to a distance of 10 feet multiple grounds driven as deep as possible separated by at least 6 feet apart are most effective.
If the grounding of a building protected with a lightning protection system is within 25 feet of a tree, the two systems should be interconnected. If the tree or grounding of the tree is within 25 feet of a water pipe, sprinkler system, or a deep well casing, a connection should be made between them.