Table of Contents
Advertisement
National Electrical Code
The following
portions
of the National
Electrical
Code are provided
to assist you with the installation
of
your digital
satellite
antenna.
These pages
represent
only a portion
of the entire National
Electrical
Code,
and
should
be consulted
for reference
purposes
only.
For the complete
code, please refer to the National
Electrica! Code Handbook.
250-1.
Scope.
This article covers general
requirements
for grounding
and bonding
of electrical
installations,
and specific requirements
in (a) through
(f) below.
(a) Systems,
circuits, and equipment
required,
permitted,
or not permitted
to be grounded.
(b) Circuit
conductor
to be grounded
on grounded
systems.
(el Location
of grounding
connections.
(d) Types and sizes of grounding
and bonding
conductors
and electrodes.
(e) Methods
of grounding
and bonding.
(f) Conditions under which guards, isolation, or
insulation
may be substituted for grounding.
250-81.
Grounding
Electrode
System.
If available
on the premises
at each building
or structure
served,
each item (a) through
(d) below, and any made
electrodes
in accordance
with Sections 250-83 (c) and
(d), shall be bonded
together
to form the grounding
electrode
system.
Interior metal water piping located
more than 5 feet (152 cm) from the point of entrance
to the building
shall not be used as a conductor
to
interconnect
the electrodes
and the grounding
electrode
conductor.
The bonding
jumper shall be
installed
in accordance
with Sections 250-92 (a) and
(b), shall be sized in accordance
with Section 250-94,
and shall be connected
in the manner
specified
in
section
250-115.
The uanspliced grounding
electrode
conductor
shall be permitted
to run to any
convenient
grounding
electrode
available in the
grounding
electrode
system.
It shall be sized for the
largest grounding
electrode
conductor
required
among
all the available
electrodes.
(a) Metal Underground Water Pipe. A metal
underground water pipe in direct contact with the
earth for 10 feet (3.05 m) or more (including any
metal well casing effectively bonded to the pipe) and
electrically continuous (or made electrically
continuous by bonding around insulating joints or
sections
or insulating
pipe) to the points
of
connection
of the grounding
electrode
conductor
and
the bonding
conductors.
Continuity
of the
grounding
path or the bonding
connection
to interior
piping
shall not rely on water
meters.
A metal
underground
water
pipe shall be supplemented
by
an additional
electrode
of a type specified
in Section
250-81 or in Section
250-83. The supplemental
electrode
shall be permitted
to be bonded
to the
grounding
electrode
conductor,
the grounded
service-entrance
conductor,
the grounded
service
raceway,
or any grounded
service enclosure.
250-83.
Made and Other
Electrodes.
Where none
of the electrodes
specified
in Section 250-81 is
available,
one or more of the electrodes
specified
in
(b) through
(d)* below shall be used.
Where
practicable,
made electrodes
shall be embedded
below
permanent
moisture
level.
Made electrodes
shall be free from nonconductive
coatings,
such as
paint or enamel.
Where
more than one electrode
is
used, each electrode
of one grounding
system
(including
that used for lightning
rods) shall not be
less than 6 feet (1.83 m) from any other electrode
of
another grounding
system.
(c) Rod and Pipe Electrodes.
Rod and pipe
electrodes
shall not be less than 8 feet (2.44 m) in
length and shall consist of the following
materials,
and shall be installed
in the following
manner:
(1) Electrodes
of pipe or conduit shall not be
smaller
than 3/4 -inch trade size and, where of iron or
steel, shall have the outer surface
galvanized
or
otherwise
metal-coated
for corrosion
protection.
(2) Electrodes
of rods of iron or steel shall be at
least 5/s inch (15.87 mm) in diameter.
Stainless
steel
rods less than 5/8 inch (15.87 ram) in diameter,
nonferrous
rods, or their equivalent
shall be listed
and shall not be less than _/a inch (12.7 mm) in
diameter.
(3) The electrode
shall be installed such that at
least 8 feet (2.44 m) length is in contact with the soil.
It shall be driven to a depth of not less than 8 feet
(2.44 m) except that, where rock bottom is
encountered,
the electrode
shall be driven at an
oblique
angle not to exceed 45 degrees from the
vertical
or shall be buried in a trench
that is at least
21/2 feet (762 ram) deep.
The upper end of the
electrode
shall be flush with or below ground
level
unless
the aboveground
end and the grounding
electrode
conductor
attachment
are protected
against
physical
damage
as specified
in Section 250-117.
48
Appendix: Other Information
Advertisement
Table of Contents
