This part of the A300 standards applies to installation and maintenance of Lightning Protection Systems in Trees. Part 4 Lightning Protection Systems addresses:
- Tools and equipment
- Connectors and Fasteners
- Ground terminals
- Installation practices
A300 Part 4 Lightning Protection Systems standards recognize three basic ground systems:
- Single ground rod: A ground terminal composed of one ground rod.
- Multiple ground system: A ground terminal composed of two or more ground rods or copper ground plates.
- Horizontal ground system: A ground terminal composed of ground rod(s) or copper ground plate(s) that are not fully driven or installed in the ground due to site conditions.
The objective of a tree lightning protection system is to provide a preferred path to ground for the electri¬cal charge; protected trees shall not be considered a safe haven from lightning strikes.
When considering tree lightning protection systems, the user has to keep in mind that the purpose of the ANSI A300 (Part 4)-2008 standard is to provide standards for developing specifications for tree lightning protection system installation (43.1). The only reason for installing a tree lightning protection system is to reduce the risk of damage to trees from lightning strikes (43.2). Tree lightning protection systems do not protect buildings or property from damage or provide safe havens from lightning. The user needs to understand that the only objective for a tree lightning protection system is to provide a preferred path to ground for the electrical charge (46.1).
If there is danger from side flash or other lightning-induced damage to non-tree components, property, buildings, etc., or, the trees owner or owners agent have a different objective than outlined in this standard (46.1), then the appropriate standard practices must be followed as detailed by this standards normative references (44).
Which trees should be protected from lightning strikes?
- Trees with trunks within 10 feet (3 m) of a structure, or with branches that extend to a height above the structure, should be equipped with a lightning protection system because of the danger of side flash, fire, or superheating of the moisture in the tree, which could result in the splintering of the tree. (NFPA - 780 F-1)
- Trees of historical interest; trees of unusual value; shade trees within 10 feet (3 m) of a building; trees with branches overhanging buildings; tall trees in recreational or park areas; trees that are more likely to be struck by lightning due to their location, such as isolated trees on a hill, in a golf course, or in a pasture, etc.; and similar trees; should be equipped with lightning protection systems.
- Lightning protection for trees is intended to safeguard trees against damage caused by lightning; protected trees should not be considered a safe haven from lightning strikes.
Part 4 Lightning Protection Systems Resources:
Download “Providing Lightning Protection,” a TCI Magazine article written by Guy Meilleur.