e. When air terminals are over two (2) feet high, braces shall be
provided to prevent damage to the roof from whipping.
Air terminals at the end of the building should not be set more than
two (2) feet from the end of the roof.
a. Air terminals, which are two (2) feet high, should not exceed 25
feet spacing on ridges, parapets, or the perimeter of buildings with flat
b. Where it is necessary to exceed this spacing, make sure that air
terminal height is increased no less than two (2) inches for each foot over
When metal ventilators are installed on the maintenance building
(Figure 1-2), see that an air terminal is installed on the ventilator.
a. If the air terminal is installed on one side of the metal
ventilator, it should be bonded near the top and bottom of the ventilator
and securely connected to the ridge cable in three (3) places. (See Figure
b. If a non-metallic ventilator is present, the air terminal may be
mounted on the ventilator or its side; there must be a direct connection
between the air terminal and the ridge cable.
Ridge cables or roof connectors may be connected directly to the roof.
a. Sharp bends or turns in ridge conductors shall not exceed an angle
of 90 degrees.
c. The cables must be securely fastened every four (4) feet along the
ridge and down the building to the ground.
Down conductors shall be electrically continuous from the air terminals
or ridge cables to the ground connections.
a. Down connectors should be placed over the extreme outer portions of
the building, such as corners.
b. There must be no less than two down connectors on any structure;
they shall be as widely separated as practicable. The preferable location
is at opposite corners.
c. Rectangular structures of more than 110 feet with gable