feet. Make all connections electrically continuous and have surface
contact of at least 1935 square mm 3 square inches.
3.2.3
Steel Frame Building
Make the steel framework of the building electrically continuous.
Electrical continuity may be provided by bolting, riveting, or welding
unless another specific method is indicated. Connect air terminals to the
structural steel framework at the ridge. Provide short runs of conductors
to join air terminals to the metal framework so that proper placing of air
terminals is maintained. Separate down conductors from air terminals to
ground connections are not required. Where water system enters the
building, securely connect structural steel framework and water system at
point of entrance by a ground connector. Make connections to pipes by
means of ground clamps with lugs. Make connections to structural framework
by means of nut and bolt or welding. Make connections between columns and
ground connections at bottom of steel columns. Make ground connections to
grounds or ground loop runs from not less than one-half of the columns
distributed equally around perimeter of structure. When no water system
enter the structure, run ground connections from steel columns distributed
equally around the perimeter of the structure. Bond metal doors, windows,
gutters, and similar metal installation to steel work of the building.
Provide a grounding electrode for each ground connection.
3.2.4
Ramps and Covered Passageways
Ramps and covered passageways which are in the zone of protection of a
lightning protection system, as defined by NFPA 780, need no additional
lightning protection. However, ramps and covered passageways which are
outside the zone of protection of a lightning protection system shall be
provided with a lightning protection conforming to the requirements for
lightning protection systems for buildings of similar construction. Place
a down conductor and a driven ground at one of the corners where the ramp
connects to each building or structure. Connect down conductor and driven
ground to the ground loop or nearest ground connection of the building or
structure. Where buildings or structures and connecting ramps are clad
with metal, connect metal of the buildings or structures and metal of the
ramp in a manner to ensure electrical continuity, in order to avoid the
possibility of a flash-over or spark due to a difference in potential.
Make connections electrically continuous and have a surface contact area of
at least 1935 square mm 3 square inches.
3.2.5
Tanks and Towers
3.2.5.1
Wooden Tanks and Towers
Electrically interconnect lightning protection system components (such as:
air terminals, ridge cables, down conductors, ground connections, and
grounds) to form the shortest distance to ground without passing through
any nonconducting parts of the structure. Where the roof of the structure
ends in a peak, a single air terminal not less than 610 mm 2 feethigh will
be regarded as sufficient. When structure does not end in a peak, provide
air terminals not less than 610 mm 2 feet high at intervals not exceeding
7620 m 25 feet along the perimeter of the structure. When the tank or
tower is an adjunct of a building, near or touching the perimeter, extend
one of the down conductors directly to a ground connection and connect the
other to lightning protection of the building. When tank or tower is set
well within the perimeter of the building, connect both down conductors to
lightning protection system of the building. When height of the structure
SECTION 13100N
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