The Go-To Guys for Lightning Protection Systems for Stables, Barns & Farms
When you’ve been providing lightning protection systems in the middle of horse country for more than five decades, you know what it takes to protect barns, stables, and entire farms from the damaging forces of mother nature.
Your Farm Building Protection Standards
Lightning can enter a building in one of four ways:
- It can strike a metal object on the roof.
- It can strike a building directly (called a direct strike).
- It can strike a tree or silo near the building and jump to the building. This occurs when the building provides an easier path to ground.
- It can strike a power line or a wire fence and follow the line or fence to the building.
A properly designed lightning protection system safeguards vulnerable structures, equipment, and trees by providing an easy path to a ground, which harmlessly dispels the electrical charges. Protection should also be provided for objects located where a lightning strike’s current might sideflash, such as electrical wires or metal devices on building roofs.
Depending on their location, some silos should be tied into a building’s lightning protection system. It is also possible to extend protection to trees situated near farm structures or that offer cover for livestock. Detailed specifications for these systems can be found in the codes and standards cited later in this fact sheet.
Installation Codes and Standards
Installing lightning protection systems is not a do-it-yourself job. To ensure that a lightning protection system is safe and effective, it should be designed and installed by trained professionals.
Certain codes and standards must be followed when lightning protection systems are installed. Standards and sources are listed below:
LPI-175: The lightning protection code, published by the Lightning Protection Institute.
NFPA 78: National Fire Protection Association Lightning Protection Code.
ASAE EP381: American Society of Agricultural Engineers, Engineering Practice.
The Lightning Protection Institute will certify a lightning protection system that meets all its requirements. To retain certification, the system must undergo regular maintenance and be inspected annually. Maintenance of any lightning protection system is vital to make sure the system will work when it is needed. Weather conditions, such as high winds, can damage components of a lightning protection system. Building additions and re-roofing can also affect a system’s performance.
Components of the System
Main Components
The major components of a building’s lightning protection system are air terminals, conductors, and ground electrodes.
Air terminals are more commonly known as lightning rods. They are placed at intervals on the roof and on any high points projecting from the roof. Lightning rods are made of solid copper or aluminum and are drawn to a point. Their design and placement ensure that lightning will strike them and not another part of a building. Specifications for lightning rods vary depending on a roof’s type and size. Recommended height, anchoring methods, and spacing intervals can be found in the codes and standards previously listed.
Conductors are specially designed cables made from copper or aluminum that provide a low-resistance path to the ground for lightning’s electrical charges. Conductors can be classified into three categories:
- Main conductors interconnect all the lightning rods and down conductors.
- Down conductors connect the main conductors to the ground. Each building needs at least two down conductors located at opposite corners of the building. Codes should be consulted to determine the number and location of down conductors for different building types.
- Branch conductors connect metal objects such as vent fans, gutters, and water pipes to the grounding system to protect against possible sideflashes.
Ground electrodes are the ground connections for the lightning protection system, which serve to dissipate electrical charges safely. The down conductors are securely fastened to the ground electrodes. The type of ground connection used depends on the conductivity of the soil. Code specifications must be followed to make sure the most effective ground connection is made for a particular soil type.
The best method for eliminating lightning-induced sideflashes between metal bodies is common grounding. This means that the grounds for all the electrical systems, the telephone service, and underground metal piping are connected to the lightning protection system. Plastic piping, which has become common in recent years, does not conduct lightning’s electrical charges and requires special grounding.