ANSI A300 (Part 4)-2008 Lightning Protection Systems

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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
• Materials
• Conductors
• 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.
  

Advisory Notice:  The objective of a tree lightning protection system is to provide a preferred path to ground for the electri­cal charge; protected trees shall not be considered a safe haven from lightning strikes.  Learn more.

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.

Learn more about lightning protection:

Providing Lightning Protection (PDF - 630 KB) - a TCI magazine article written by Guy Meilleur