Conductors
Minimum Size of Conductors (AWG) Where Maximum Open Span Length Is
11 m to
Less Than 45 m (35 ft Over 45 m
Material 11 m (35 ft) to 150 ft) (150 ft)
Aluminum alloy, 19 14 12 hard-drawn
copper
Copper-clad 20 17 14
steel, bronze, or other
high-strength material
(B) Self-Supporting Antennas. Outdoor antennas, such as vertical rods, dishes, or dipole structures, shall be of corrosion-resistant materials and of strength suitable to withstand ice and wind loading conditions and shall be located well away from overhead conductors of electric light and power circuits of over 150 volts to ground, so as to avoid the possibility of the antenna or structure falling into or making accidental contact with such circuits.
810.17 Size of Lead-in — Receiving Station. Lead-in conductors from outside antennas for receiving stations shall, for various maximum open span lengths, be of such size as to have a tensile strength at least as great as that of the conductors for antennas as specified in
810.16. Where the lead-in consists of two or more
conductors that are twisted together, are enclosed in
the same covering, or are concentric, the conductor size
shall, for various maximum open span lengths, be such
that the tensile strength of the combination is at least
as great as that of the conductors for antennas as
specified in 810.16.
810.18 Clearances — Receiving Stations.
(A) Outside of Buildings. Lead-in conductors attached to buildings shall be installed so that they cannot swing closer than 600 mm (2 ft) to the conductors of circuits of
250 volts or less between conductors, or 3.0 m (10 ft) to
the conductors of circuits of over 250 volts between
conductors, except that in the case of circuits not over
150 volts between conductors, where all conductors
involved are supported so as to ensure permanent
separation, the clearance shall be permitted to be
reduced but shall not be less than 100 mm (4 in.). The
clearance between lead-in conductors and any
conductor forming a part of a lightning protection
system shall not be less than 1.8 m (6 ft). Underground
conductors shall be separated at least 300 mm (12 in.)
from conductors of any light or power circuits or Class 1
circuits.
Exception: Where the electric light or power conductors, Class 1 conductors, or lead-in conductors are installed in raceways or metal cable armor.
FPN No. 1: See 250.60 for use of air terminals. For further information, see NFPA 780-2008, Standard for the Installation of Lightning Protection Systems, which contains detailed information on grounding, bonding, and spacing from lightning protection systems.
FPN No. 2: Metal raceways, enclosures, frames, and other non-current-carrying metal parts of electrical equipment installed on a building equipped with a lightning protection system may require bonding or spacing from the lightning protection conductors in accordance with NFPA 780-2008, Standard for the Installation of Lightning Protection Systems. Separation from lightning protection conductors is typically 1.8 m (6 ft) through air or 900 mm (3 ft) through dense materials such as concrete, brick, or wood.