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Lightning Rods for Trees

The mechanics of a lightning cable system are not very difficult to employ, but you will probably need a professional to do the job. There are some calculations that must be made by professionals to ensure your tree is well protected.

There are 4 different types of systems depending on whether additional support is needed for branches that are weak. But generally for a healthy tree the Hub and Spoke system can be used. This is where all cables are connected to a central hub or main cable. The main conducting cable should run between the highest accessible part of the tree down the trunk and into the ground.  If a tree is forked, both forks need a cable. If it is fewer than three feet in diameter, one cable is fine, but for a larger trunk use two or more cables along the trunk on opposite sides.  Smaller cables then run along major branches and are spliced securely into the main cable(s).   Usually, three to eight branch cables are used, depending on the tree size and shape. Allow enough slack for swaying in the wind and for moving air terminals as the branch grows longer. Copper is the wire of choice for both the main cable and the branch cables.

Lightning protection systems need to be adequately grounded. If it is within 25 feet of water pipes, sprinkler systems or well casings you can make interconnections with these for grounding. Otherwise, place ground rods around your tree.  The pattern of the rods depends on your soil type. In a clay soil, generally the rod(s) are placed 10 feet deep and the main cable is run through a trench and firmly secured to the rod. In sandy soils or in limited space you can use multiple rods that are at least 10 feet apart. In shallow or rocky soils, multiple rods of varying lengths can be buried in different patterns and interconnected to provide the necessary grounding.

As a final note, all tree lightning systems should always carry a name plate with the installer’s name and address.