How to Protect Trees From Lightning

Florida is a state where lightning strikes, and it is more than twice. With summer bringing multiple thunderstorms weekly, the chances of tree damage are quite significant.

Lightning protection systems for trees are old technology, having been developed decades ago. They consist of three connected parts. A copper cable “down-conductor” directs the charge of a strike from the air terminal, which is located in the tree top to catch the strike, to the grounding rod system, which dissipates the energy of the strike in the earth.

Because metal is a better conductor than tree tissue the lightning will follow the copper cable. It is the path of least resistance which keeps the electrical energy from damaging the tree.

The primary purpose of a lightning protection system in a tree is to protect the tree. However, it may also keep the strike from damaging adjacent objects such as structures or other plants in close proximity.

Photo Credit: Les Harrison (UF IFAS Extension Agent Emeritus).

Too often when unprotected trees receive a strike the charge jumps to another tree or a structure containing metal. A tree with a properly grounded system minimizes this prospect.

Admittedly lightning is unpredictable, and the charge released can behave erratically even when the tree is protected with a system. The best protection for nearby structures is a properly installed system which is securely grounded.

A lightning protection system is important when an older tree has had cabling or rodding placed on it for structural support. This practice is common on stately live oaks when the owners or land managers want to extend the life of an exceptional tree while minimizing the risk of damage or injury from falling limbs.

The installation of metal cables or rods does not increase the chance of a lighting strike. However, if a strike occurs, the metal fixtures and fittings will act as conductors.

The lightning hit will likely result in the energy being conducted into the woody part of the tree. The consequences will be extreme damage to the tree which would necessitate its removal.

If the tree has a lightning protection system properly installed which grounds all metal parts, it can serve to safely direct the strike away from the tree. This outlay will serve to protect the investment made in the structural enhancement of a valuable and/or historic tree.

Lastly, hire a company with certified personnel who are trained and have experience in proper installation techniques. Industry approved methods for tree care can be found at the American National Standards Institute ANSI-A300 website.

About the author
Edwin Duke and Sam Hand

Edwin R. Duke, Associate Professor, College of Agriculture and Food Sciences; FAMU Cooperative Extension, Tallahassee, FL 32307. Samuel E. Hand, Jr., Associate Professor and Director of Industry Credentialing Training Programs, FAMU Cooperative Extension, Tallahassee, FL 32307.

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