NOTE: Determine the size, type, and number of
ground rods to be used, based on local conditions,
earth resistivity data, and on the size and type of
the electrical installation. Copper clad steel rods
will be specified for normal conditions. Zinc
coated steel or stainless steel rods will be used
where low soil resistivities are encountered and
galvanic corrosion may occur between adjacent
underground metallic masses and the copper clad
rods. Stainless steel rods have a longer life than
zinc coated steel, but use of stainless steel must
be justified based on the higher cost. Rods 15.9 mm
(5/8 inch) in diameter and 2.4 m (8 feet) in length
are generally acceptable; however in rocky soils
19.1 mm (3/4 inch) rods will be specified. In high
resistivity soils, 3.1 m (10 feet) or sectional rods
may be used to obtain the required resistance to
ground; however, where rock is encountered,
additional rods, a counterpoise, or ground grid may
be necessary.
Coordinate and standardize rod selection for
individual facilities with other specification
sections.
**************************************************************************
Ground rods shall be of [copper clad steel conforming to UL 467] [zinc
coated steel conforming to ANSI C135.30] [solid stainless steel] not less
than [15.9] [19.1] mm [5/8] [3/4] inch in diameter by [2.4] [3.1] m [8]
[10] feet in length of the sectional type driven full length into earth.
2.11
POLES
**************************************************************************
NOTE: Select wind velocities from 50 year mean
recurrence isotach maps issued by the U.S. Weather
Bureau or reproduced in pole manufacturer's
literature. For areas not covered by such a map,
select the appropriate wind gust velocity from IEEE
C2 and divide by 1.3. Round off values to the
nearest nominal size given, except that when extreme
wind loading values (values above 161 km/hour (100
mph)) occur, it is recommended that pole
manufacturers be consulted as to the availability of
poles designed for such pressures. Generally,
anchor bolt-mounted poles will be used; however, the
application may make the use of embedded concrete
poles desirable. Metal poles will not be embedded
since corrosion may occur. Climbing facilities will
be provided as required by the using service.
**************************************************************************
Metal and concrete poles shall be the pole manufacturer's standard design
for supporting the number of fixtures indicated. Poles shall be designed
for a wind velocity of [31.3] [35.8] [40.2] [44.7] [49.2] [_____] m/second
[70] [80] [90] [100] [110] [_____] mph at the base of the pole, for a wind
gust factor of 1.3, and for the height and drag factors recommended by
AASHTO LTS-4. The effective projected area of luminaires and other
pole-mounted devices shall be taken into account in pole design. Poles
SECTION 16528A
Page 21
Previous Page
