A lightning protection system performs a simple task. It provides a specified path on which lightning can travel. When a home is equipped with a lightning protection system, the destructive power of the lightning strike is directed safely into the ground, leaving the home, family members and personal belongings unharmed.
The Primary Components
A lightning protection system should include all of the following elements, which work together to prevent lightning damage.
- Air Terminals (rods)
- Conductor (cable)
- Bonds with metallic bodies
- Ground Terminations
- Surge Arrestors
Modern homes are especially vulnerable to havoc that lightning can wreak on electronic equipment. T assure the highest level of protection, UL Listed Surge Arrestors should be installed on electrical service panels and other incoming lines.
Lightning Rods protect the home from a direct strike to the home thus protecting the structure from physical damage or fire bur Arrestors are the first line of defense against harmful electrical surges from entering through electrical power lines.
General Design Rules
All buildings must have two groundings as widely separated as possible, preferably at diagonally opposite corners if perimeter distance around the building at ground level is 250 feet or less.
If building perimeter is between 250 feet and 350 feet, then three groundings are required. If building is between 350 feet and 450 feet, then four groundings, etc.
Lightning Protection System shall be applied to metal covered buildings in like manner as on buildings without metal coverings.
Cables shall be free of sharp turns and "u" or "v" pockets. Cables shall remain horizontal or downward path towards the ground.
Cautions in the Use of Both Copper and Aluminum:
1—Copper equipment shall not be used on aluminum roofs or other aluminum surfaces - including bare galvanized steel. (Use Aluminum Equipment for these).
2—Copper and aluminum conductors shall not be interconnected except with acceptable bimetallic connectors
3—Aluminum equipment shall not be used underground.
4—Aluminum equipment shall not be used on copper roofing or other copper surfaces.
TYPICAL RESIDENTIAL LIGHTNING PROTECTION SYSTEM
Design Rules: Space roof lightning rods (Air Terminals) evenly, no more than 20 feet apart or 25 ft. apart if Lightning Rods are over 24” tall. End rods should be no more than 2 feet from the end of roof or outside corner’s. Fasten cable every 3 feet with #2 loop’s and nail’s or screws. Connect vents and antennas with clamp or lug if within 6 feet of the lightning cable. For a neat job run the down cables next to down spouts, molding, etc. and then connect to ground rods (make ground connection below ground as shown at right).
A Lightning Protection System is intended to last the lifetime of the structure that it protects and typically only requires maintenance when a home or structure is changed structurally or mechanically.