Transcript PPS - Satellite and Broadcast Communications Association

NEC
Grounding/Bonding
October 2009
Introduction
This course is designed to provide the participant with
the necessary understanding of the reasons
NEC code discussed in
Grounding & Bonding is required on each DIRECTV this course is based off
the NEC 2002 code.
Satellite System installation.
This course provides recommendations with respect
to grounding of a DIRECTV Satellite System. The final
grounding/bonding method is dictated by State and
Local electrical codes. However, the electrical
inspectors may require more stringent grounding
methods.
Important Note: Adherence to these requirements is
ultimately the responsibility of the local site or office.
Before starting this course, it is recommended that
you identify which NEC® code is applicable for your
jurisdiction or jurisdictions, if your area covers more
than one.
2
Course Objectives
Upon completion of this course, you will have an
understanding of the following topic areas:
Why We Ground
“What is the NEC®”
Service Reduction
DIRECTV Equipment
The NEC®, Application for DIRECTV
Underwriters Laboratory (UL) explained
NEC® Sections Defined
NEC® Adoption by State
Technician Grounding Scenarios
3
Why do I need this course?
There are two reasons for grounding:
The first, it is the law; this law is to keep us all safe as well as
the customer.
The second reason is DIRECTV requires it. Non-compliance
causes money wasted on unnecessary truck rolls for service
and/or equipment issues. You want job security… do the job
right and customers will sell DIRECTV to their friends for us.
4
Why We Ground
5
Why We Ground
NEC® 810.21 (H) Bonding of Electrodes.
The #10 AWG wire cannot exceed 20 feet in length.
Your specific area may
require other wire types
as noted by state and
local codes.
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
v
Service
Panel
This example does not allow for a
grounding wire to exceed 20ft – it is only
meant to illustrate the dispersion of a
power surge caused by lightening
6
Why We Ground
We will discuss in this section the top ten reasons to ground:
1. Limit voltages due to lightning
Prevent lightning from striking
the dish.
NOT to carry the current from a
lightning strike safely to ground.
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
v
Lightning strike spreads energy
Service
Panel
Preferred path
Bonding the ODU
7
This example does not allow for a
grounding wire to exceed 20ft – it is only
meant to illustrate the dispersion of a
power surge caused by lightening
Ground Block
Why We Ground
2. Line Surges
Source of over-voltage is, in a properly grounded system,
provided with an alternative path around the electrical system
of your home or workplace by intentionally connecting the
system to the earth.
Proper grounding of the antenna mast and lead-in cables is
somewhat effective in protecting receiving equipment from
voltage transients that result from lightning.
8
Why We Ground
3. Unintentional contact with high voltage lines
Tornados, high winds, and strong storms can bring
power lines down.
Power line insulation can wear
over time and can come into
contact with nearby objects.
9
Why We Ground
4. Dissipate static electricity
The satellite ODU sits outside where wind
will create a static charge on the dish itself
and the wire attached to it.
This action is similar to walking across
carpet and then touching another object,
which causes a difference of potential
resulting in transfer of the charge.
10
Why We Ground
5. Potential Difference
Common connection of the two separate
systems (electrical and DIRECTV) is
ultimately made at the IRD if no ground
connection is made
If the system is not bonded to
the main service ground, you
could experience an
unbalanced ground within the
system.
Not grounding to the house
electrical system leads to a
difference in potential between
two grounds.
11
v
Service
Panel
Purpose of this drawing is to illustrate
“Grounding & Bonding.” All other specific
installation requirements are outlined in
the DIRECTV New Hire Training Program
Why We Ground
6. Provide a drain for signals and noise captured by the
shield
Bonding the shield serves to nullify the effects of stray
signals by "grounding out," or reducing to a zero potential,
the voltages which are picked up by the outer shield.
12
Why We Ground
7. Ground Loops
A ground loop occurs when there is more than one bond connection
path between two pieces of equipment. The duplicate bonding paths
form the equivalent of a loop antenna, which very efficiently picks
up interference currents.
Lead resistance transforms these currents into voltage fluctuations.
13
Why We Ground
8. Lawsuits
Don’t expose yourself and the company to the consequences
of not following the code.
Ground/bond all installs in compliance with the applicable
code, be it NEC®, state or local.
14
Why We Ground
9. Personal injury
Article 90 of the NEC® covers personnel safeguarding of
persons and property.
This will be covered in the NEC® section
Drawing is intended to represent a typical residential power system, systems in your area
maybe different.
By no means does this give anyone the right to access the residential power system.
Wall Recepticle
Utility Meter
Panel
Main
Breaker
Breakers
Neutral Wire
Hot Wire(s)
Hot Wire
Neutral Wire
Bus Bar
Ground Rod
drawing length is not
representative of NEC article
250.2(a)(5) requirements
15
Why We Ground
9. Personal injury continued…
If the ground used for the
coaxial cable, which is also
connected to the receiver
cabinet, is a better ground
than the one used for the
electrical service
The entire house current
could potentially, at least
partially, flow back through
the receiver’s electrical
service ground lead.
16
Common connection of the two separate ground systems is
ultimately made at the IRD
v
Current Flow
Purpose of this drawing is to illustrate “Grounding
& Bonding” all other specific installation
requirements are outlined in the DIRECTV New
Hire Training Progam
Service
Panel
Why We Ground
10. 1st and foremost – It’s the LAW
17
Technician Scenario 1:
Using a Volt Meter
18
Technician Scenario 1
Using a Volt Meter
Volt OHM Meter
All VOMs have probes. These probes are color coded red
and black and plug in the front of the VOM. The black is the
ground or negative and the red is hot or positive.
Connecting Leads
Most VOMs have 3 plug-in locations
on their face for probes. One is
common for ground, one is usually
marked V for voltage, and the third is
marked Ohms or has a symbol Ω.
19
Technician Scenario 1
Reading Voltage
The selector switch or dial on the meter should be set to
read AC volts and at a setting where the meter can read
110-125 volts AC.
The test probes must be
connected into the correct
meter inputs, place the red
and black probes into the
slots identified to the right.
Voltage should be
approximately 110v AC.
20
Technician Scenario 1
Caution should always be used when testing the output
voltage of an electrical outlet. If you make contact with the
exposed ends of the leads an electric shock could occur that
could cause injury.
Insert the Red and Black probes into the Neutral and Ground
positions. The volt meter should register less than 1v AC,
voltage higher than this could indicate improper wiring.
21
Grounding Requirements
The length of the #10 AWG grounding wire placed between
our ground block and the house grounding electrode
system must not exceed 20 feet in length.
If the ground block is farther
than 20 feet from any part of
the grounding electrode
system, consider rewiring
the cables from the ODU to
a new ground block location
that is within 20 feet of the
ground source.
Remember that common connection of the
two separate systems (electrical and
DIRECTV) is ultimately made at the IRD if
no ground connection is made
v
Purpose of this drawing is to illustrate
“Grounding & Bonding.” All other specific
installation requirements are outlined in
the DIRECTV New Hire Training Program
22
Service
Panel
#6AWG bond wire between an additional
ground rod installed more that 20 feet from
the electrical service ground rod
Grounding Requirements
Allows for the connection to a
grounding electrode system
that is more than 20 feet from
the ground block, but more
equipment is required.
Remember that common connection of the
two separate systems (electrical and
DIRECTV) is ultimately made at the IRD if
no ground connection is made
v
An additional ground rod or
grounding electrode would
need to be installed at the
ground block location, and a
heavy wire would need to be
installed between the
additional ground rod and the
home’s main electrical system
electrode.
23
Purpose of this drawing is to illustrate
“Grounding & Bonding.” All other specific
installation requirements are outlined in
the DIRECTV New Hire Training Program
Service
Panel
#6AWG bond wire between an additional
ground rod installed more that 20 feet from
the electrical service ground rod
Grounding Requirements
Ground rods installed in
addition to the primary
ground rod must be bonded
to the existing ground rod
with a #6 AWG bonding wire
Electrical system ground rods
must be installed by a
licensed electrician
Remember that common connection of the
two separate systems (electrical and
DIRECTV) is ultimately made at the IRD if
no ground connection is made
v
Purpose of this drawing is to illustrate
“Grounding & Bonding.” All other specific
installation requirements are outlined in
the DIRECTV New Hire Training Program
Service
Panel
#6AWG bond wire between an additional
ground rod installed more that 20 feet from
the electrical service ground rod
24
Technician Scenario 2:
AC Voltage at Ground Block
25
AC Voltage at Ground Block
Technician arrives at a service call to find AC voltage on the
coaxial cable at the ground block.
Suggestions:
Disconnect all DIRECTV receivers within the installation
Test ALL electrical outlets and consider using a non-contact
voltage detector
Notify the customer and your supervisor of all electrical
issue
Follow your company specific SAFETY guidelines!
26
AC Voltage at Ground Block
Consider the following items when working around or near any
electrical system on any installation inside, outside, attic and the
crawl space of any building:
Exposed electrical lines or lighting terminals
Electrical wiring with deteriorated insulation
Electrical fencing
27
AC Voltage at Ground Block
Effects of Electric Current in the Human Body
Current
Reaction
Below 1 milliamp
Generally not perceptible.
1 milliamp
Faint Tingle.
5 milliamps
Slight shock felt; not painful but disturbing. Average individual can let go.
Involuntary reactions can lead to other injuries.
6-25 milliamps (women)
Painful shock, loss of muscle control.
9-30 milliamps (men)
The freezing current or “let-go” range.
50-150 milliamps
Extreme pain, respiratory arrest, severe muscular contractions. Death is possible
1,000-4300 milliamps (1.0 –
4.3 amps)
Rhythmic pumping action of the heart ceases. Muscular contraction and nerve
damage occur; death likely.
10,000 milliamps (10 amps)
Cardiac arrest, sever burns; death probable.
Information source: W.B. Kouwenhoven, “Human Safety and Electric Shock”, November 1968
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“What is the NEC®”
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What is the NEC
Practical Safeguarding. The purpose of this Code is the practical
safeguarding of persons and property from hazards arising from the use of
electricity.
The NEC® is prepared by the National Electrical Code Committee, which consists of a
Technical Correlating Committee and 20 code-making panels. The code-making
panels have specific subject responsibility within the Code.
The NEC® Code covers the installation of electric conductors, electric equipment,
signaling and communications conductors and equipment and fiber optic cables and
raceways for the following:
Public and private premises, including buildings, structures, mobile homes,
recreational vehicles and floating buildings.
Yards, lots, parking lots, carnivals and industrial substations.
State & Local authorities adopt the NEC® code based on year of release as a
guideline; in turn, these authorities can exceed the requirements as dictated by the
NEC® code that is adopted for use.
The NEC® code may be adopted as an enforceable standard or set of requirements
by states, counties and / or municipalities.
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How does it apply
NEC 90.4 Enforcement
This Code is intended to be
suitable for mandatory
application by governmental
bodies that exercise legal
jurisdiction over electrical
installations, including
signaling and communications
systems, and for use by
insurance inspectors.
The authority having
jurisdiction for enforcement of
the Code has the
responsibility for making
interpretations of the rules, for
deciding on the approval of
equipment and materials, and
for granting the special
permission contemplated in a
number of the rules.
31
NEC® Codes are updated every three years
Sections are updated, then referenced
throughout the code.
Current code in effect as deemed by the
local authority having jurisdiction.
Emphasis is on grounding & bonding.
State, county or municipal codes may
supersede the NEC®, these are typically
more stringent in nature and may
outline fees and penalties.
Interpretation
Many people claim to know the code.
There is conjecture among licensed
individuals, states, and municipalities.
Every reference must be studied to find
the true meaning of the code.
Rules change from NEC® revision to
NEC® revision
State and local assertions supersede
the NEC®, but are required to be written
into law.
AHJ is defined as “Authority Having
Jurisdiction”, this could be the state or
local inspector, who in turn has the final
say regarding requirements.
UL & Grounding
32
How does it apply
UL stands for Underwriters Laboratories,
and is a well-known testing laboratory that
develops standards and test procedures
for materials.
33
Grounding and Bonding Equipment UL 467
Scope 1.1
a. This Standard applies to grounding and bonding equipment for use in
accordance with the National Electrical Code, NFPA 70 (NEC).
b. 1.2 This Standard applies to the following grounding and bonding
equipment:
i. ground clamps, bonding devices, grounding bushings, watermeter shunts, grounding electrodes, and the like used in a
grounding system;
ii. equipment for making electrical connections between the
grounding conductors used in electrical power systems, noncurrent-carrying metal parts of electrical equipment, armored
grounding wires, metal raceways, and the like; and
iii. grounding electrodes;
c. equipment for making electrical connections between
i. the grounding conductors used in telecommunications
systems such as telephone, radio, CATV, network power
broadband, and the like; and
ii. grounding electrodes; and
d. hospital grounding jacks and mating grounding cord assemblies
34
Service Reduction
35
Service Reduction
Impact
Equipment failure is the number one service reason in the
network; typically accounting for more than 31% of all service
calls outlined in the Weekly Service Report.
36
Service Reduction
Impact
Almost 20% of the time the receiver is replaced
25.00%
20.00%
15.00%
Multi-Switch Replace
Replace IRD
Replace LNB
Replace ODU
10.00%
5.00%
0.00%
Jan-09
Feb-09
Mar-09
Apr-09
May-09
Jun-09
Jul-09
The information in the graphic above basically translates to:
Sites with lower grounding pass rates have higher
occurrences of IRD failures.
37
Effective grounding methods have been shown to
significantly reduce equipment failure rates.
DIRECTV Equipment
38
The IRD & Voltage
The IRD power supply knows it will receive 110vac with a variance
of +/- 5vac from a typical residential electrical power grid.
There is a Schematic for the power supply which shows specific
output voltages supplied for electronics inside each receiver.
Example of a typical Power Supply.
39
The IRD & Voltage
The power supply supplies specific dc voltages for powering
of the connected LNB, internal hard drive (for DVR models
only) internal tuner(s) and other internal components specific
to the receiver.
The power supply is designed to dissipate heat generated by
the power supply itself. This heat is a factor when the receiver
is placed into an area that does not provide for adequate
movement of air.
Inadequate movement of air then allows premature failure of a
receiver.
40
The IRD & Voltage
Voltage Issues
What happens when voltages do not reach the receiver as
designed?
What happens when unexpected voltages reach the receiver
by way of the coaxial cable?
Can small voltage fluctuations cause electronic components to
fail prematurely overtime?
41
The IRD & Voltage
Voltage Issues
Greater resistance in the installation components, LNB,
cabling, etc. can cause the power supply to run at a higher
current output mode, which leads to an excessive creation of
heat and lower voltage.
A typical residential 110vac power supply runs at 60 Hz. In
some instances, faulty electrical equipment can induce
harmonics onto the residential power supply, which in turn can
cause the receiver to loose functionality resulting in
pixelization and or signal loss.
42
The IRD & Voltage
Voltage Issues
Harmonics are comparable to
resonance that produces overcurrent surges, and is equivalent
to continuous audio feedback
through a PA system. This can
result in destroyed capacitors,
fuses, and damaged surge
suppressors.
Household items such as
microwaves, freezer motors, well
motors, arc welders and dimmers
can induce harmonics onto the
power supply for the residence.
Approximately 1/3 of the
receivers returned are found to
have no problems or the
problems reported cannot be
duplicated, and leads to unneeded costly service calls.
43
Technician Scenario 3:
Intermittent Pixelization
44
Intermittent Pixelization
Technician arrives at the service call with a customer complaint
of intermittent pixilation. What is the first thing to check?
Do you use a circuit tester frequently?
Do you use a volt / ohm meter?
Do you know how to use the volt / ohm meter correctly?
Can you isolate the IRD to another electrical circuit?
Do electrical appliances within the customer’s home affect the
IRD?
Microwaves
Freezers
Rural homes may have the following:
Well Pumps
Arc Welders
45
Intermittent Pixelization
Focus on IRD Failure
Installers and service techs can have an overwhelming impact
on service call volume from IRD failures.
There are multiple systems at work at the customer’s
residence.
The first system is the homes electrical system. It is
represented by the electrical service line, the power meter,
the conduit to the breaker panel, the breaker panel, the
internal house wiring and the ground wiring.
The second system is the DIRECTV system. It is
represented by the LNB, the outside wires, ground block,
switch, internal house wiring and the ground wiring.
Other systems include phone, cable TV and data networks.
All of these systems potentially can have different points of
ground bonding within the same electrical system.
Note: Article 810.21 (I) Common Ground Reference
46Common Ground. A single grounding conductor shall be permitted for both protectiveand operating purposes.
Intermittent Pixelization
Focus on IRD Failure
The currents and signals carried by these two separate
systems come together at one point; the receiver.
Without any grounding at all, the only place these two
systems have in common is the receiver. Unexpected
voltages on either system will want the same thing; to go to
ground.
If the electrical system has its own ground source (e.g. an
eight foot ground rod), and the DIRECTV system has a
separate ground source, unexpected voltages on either
system will have a choice of two ground sources. The
unexpected voltages will choose whichever source has the
least resistance to ground. It could be either one.
These voltages can get to either of the two ground sources
through the point at which both systems are connected;
THE RECIEVER! The transfer of voltage from one system to
the other can and will burn the receiver out. This is why it is
extremely important to use one common house ground.
Note: Article 810.21 (I) Common Ground Reference
47Common Ground. A single grounding conductor shall be permitted for both protective and operating purposes.
Intermittent Pixelization
Focus on IRD Failure
If both the home electrical system and the DIRECTV system
are grounded to the same point, the unexpected voltages will
find that there is only one choice of ground path. This directs
all transient voltages through the ground wires, and NOT
through the receiver.
Correctly grounding our installations to a common ground
source will reduce service calls caused by burned out
receivers, and increase our customer satisfaction. Our
understanding of this basic principle and our ability to ensure
its practice in the field is just one example of what sets
DIRECTV apart from its competitors, and makes us the
industry leader.
Note: Article 810.21 (I) Common Ground Reference
48Common Ground. A single grounding conductor shall be permitted for both protective and operating purposes.
Technician Scenario 4:
Tracing a Power Surge
through Multiple Grounds
49
Tracing a Power Surge through Multiple Grounds
In the event lightening
strikes the reflector, the
power surge travels along
the coaxial cable shielding
to the ground block.
At the ground block, the
potential difference to
ground is determined to be
less by the power surge if it
travels to the receiver and
then to the household
ground.
50
Common connection of the two separate ground
systems is ultimately made at the IRD
v
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
Service
Panel
Technician Scenario 5:
Tracing a Power Surge
through Multiple Grounds
51
Tracing a Power Surge through Multiple Grounds
In the event lightening
strikes the main power line,
the power surge travels
along the main power line to
the main meter panel.
Common connection of the two separate ground
systems is ultimately made at the IRD
At the main panel, the
potential difference to
ground is determined to be
less by the power surge if it
travels to the receiver by
way of the internal
household wiring and then
to the coaxial cable ground
block.
52
v
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
Service
Panel
Technician Scenario 6:
Tracing a Power Surge
through a Single Ground
53
Tracing a Power Surge through a Single Ground
In the event lightening
strikes to the main
power line, the power
surge travels along the
main power line to the
main meter panel.
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
v
At the main panel, the
power surge is diverted
to the household
ground rod.
54
Service
Panel
This example does not allow for a bonding
wire to exceed 20ft – it is only meant to
illustrate the dispersion of a power surge
caused by lightening
Technician Scenario 7:
Tracing Static
55
Tracing Static
Purpose of this drawing is to illustrate
“Grounding & Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
v
Service
Panel
This example does not allow for a grounding
wire to exceed 20ft – it is only meant to
illustrate the dispersion of static electricity
+ ++ + +
++ +
_
+ +_
+_ _ +
56
+ + +
+ +
+
+ +
++ ++ + +
+ +
Static electricity is the
result of an imbalance
between negative and
positive charges in an
object. These charges can
build up on the surface of
an object until they find a
way to be released or
discharged.
One way to discharge them
in a satellite dish
installation is to bond the
ODU mount/mast to a
ground source.
NEC® Sections
57
NEC Sections Defined
In this topic, we will discuss the NEC® codes sections that
are applicable to the satellite DBS service.
NEC Articles
Article 100 Definitions
Article 250 Grounding & Bonding
Article 300 Wiring Methods
Article 800 Communications Circuits
Article 810 Radio and Television Equipment
Article 820 Community Antenna Television and Radio
Distribution Systems (CATV)
58
Article 100 Definitions
59
Article 100 Definitions
Article 100 contains only those definitions essential to the
proper application of this Code. It is not intended to include
commonly defined general terms or commonly defined
technical terms from related codes and standards.
In general, only those terms that are used in two or more
articles are defined in Article 100. Other definitions are included
in the article in which they are used but may be referenced in
Article 100.
60
Article 100 Definitions
Approved: Acceptable to the authority having jurisdiction.
Authority: Having Jurisdiction. The organization, office, or
individual responsible for approving equipment, materials, an
installation or procedure.
Bonding (Bonded): The permanent joining of metallic parts to
form an electrically conductive path that ensures electrical
continuity and the capacity to conduct safely any current likely
to be imposed.
Bonding Jumper: A reliable conductor to ensure the required
electrical conductivity between metal parts required to be
electrically connected.
61
Article 100 Definitions
Bonding Jumper, Equipment: The connection between two or
more portions of the equipment grounding conductor.
Bonding Jumper, Main: The connection between the grounded
circuit conductor and the equipment grounding conductor at
the service.
Conductor, Bare: A conductor having no covering or electrical
insulation whatsoever.
Conductor, Covered: A conductor encased within material of
composition or thickness that is not recognized by this Code
as electrical insulation.
62
Article 100 Definitions
Conductor, Insulated: A conductor encased within material of
composition and thickness that is recognized by this Code as
electrical insulation.
Copper-Clad Aluminum Conductors: Conductors drawn from a
copper-clad aluminum rod with the copper metallurgically
bonded to an aluminum core. The copper forms a minimum of
10 percent of the cross-sectional area of a solid conductor or
each strand of a stranded conductor.
Dwelling Unit: One or more rooms for the use of one or more
persons as a housekeeping unit with space for eating, living,
and sleeping, including permanent provisions for cooking and
sanitation.
Dwelling, One-Family: A building that consists solely of one
dwelling unit.
63
Article 100 Definitions
Dwelling, Two-Family: A building that consists solely of two
dwelling units.
Dwelling, Multifamily: A building that contains three or more
dwelling units.
Dwelling, MDU: The FCC defines and MDU property as an
apartment, condominium or cooperative buildings. In addition,
it includes gated communities, mobile home parks, garden
communities and other centrally managed residential real
estate developments.
Enclosure: The case or housing of apparatus, or the fence or
walls surrounding an installation to prevent personnel from
accidentally contacting energized parts or to protect the
equipment from physical damage.
64
Article 100 Definitions
Energized: Electrically connected to a source of voltage.
Ground: A conducting connection, whether intentional or
accidental, between an electrical circuit or equipment and the
earth or to some conducting body that serves in place of the
earth.
Grounded: Connected to earth or to some conducting body
that serves in place of the earth.
Grounded Effectively: Intentionally connected to earth through
a ground connection or connections of sufficiently low
impedance and having sufficient current-carrying capacity to
prevent the buildup of voltages that may result in undue
hazards to connected equipment or to persons.
65
Article 100 Definitions
Grounded Conductor: A system or circuit conductor that is
intentionally grounded.
Grounding Conductor: A conductor used to connect
equipment or the grounded circuit of a wiring system to a
grounding electrode or electrodes.
Grounding Conductor, Equipment: The conductor used to
connect the non–current-carrying metal parts of equipment,
raceways, and other enclosures to the system grounded
conductor, the grounding electrode conductor, or both, at the
service equipment or at the source of a separately derived
system.
Grounding Electrode Conductor: The conductor used to
connect the grounding electrode(s) to the equipment
grounding conductor, to the grounded conductor, or to both, at
the service, at each building or structure where supplied from
a common service, or at the source of a separately derived
system.
66
Article 100 Definitions
Ground-Fault Circuit Interrupter: A device intended for the
protection of personnel that functions to de-energize a circuit
or portion thereof within an established period of time when a
current to ground exceeds the values established for a Class A
device.
Listed: Equipment, materials, or services included in a list
published by an organization that is acceptable to the
authority having jurisdiction and concerned with evaluation of
products or services, that maintains periodic inspection of
production of listed equipment or materials or periodic
evaluation of services, and whose listing states that the
equipment, material, or services either meets appropriate
designated standards or has been tested and found suitable
for a specified purpose.
Outlet: A point on the wiring system at which current is taken
to supply utilization equipment.
67
Plenum: A compartment or chamber to which one or more
air ducts are connected and that forms part of the air
distribution system.
Article 100 Definitions
Power Outlet: An enclosed assembly that may include
receptacles, circuit breakers, fuse holders, fused switches,
buses, and watt-hour meter mounting means; intended to
supply and control power to mobile homes, recreational
vehicles, or boats, or to serve as a means for distributing
power required to operate mobile or temporarily installed
equipment.
Premises Wiring (System): That interior and exterior wiring,
including power, lighting, control, and signal circuit wiring
along with their associated hardware, fittings, and wiring
devices, both permanently and temporarily installed, that
extends from the service point or source of power.
Such wiring does not include wiring internal to appliances,
luminaries (fixtures), motors, controllers, motor control
centers and similar equipment.
68
Article 100 Definitions
Raceway: An enclosed channel of metal or nonmetallic
materials designed expressly for holding wires, cables, or bus
bars, with additional functions as permitted in this Code.
Raceways include, but are not limited to, rigid metal conduit,
intermediate metal conduit, flexible metallic tubing, flexible
metal conduit, electrical metallic tubing, under floor raceways,
cellular concrete floor raceways, cellular metal floor raceways
and bus ways.
Receptacle: A receptacle is a contact device installed at the
outlet for the connection of an attachment plug. A single
receptacle is a single contact device with no other contact
device on the same yoke. A multiple receptacle is two or more
contact devices on the same yoke.
Service Drop: The overhead service conductors from the last
pole or other aerial support to and including the splices, if any,
connecting to the service-entrance conductors at the building
or other structure.
69
Article 100 Definitions
Service Equipment: The necessary equipment, usually
consisting of a circuit breaker(s) or switch(es) and fuse(s) and
their accessories, connected to the load end of service
conductors to a building or other structure, or an otherwise
designated area, and intended to constitute the main control
and cutoff of the supply.
Service Point: The point of connection between the facilities of
the serving utility and the premises wiring.
Ventilated: Provided with a means to permit circulation of air
sufficient to remove an excess of heat, fumes, or vapors.
Voltage to Ground: For grounded circuits, the voltage between
the given conductor and that point or conductor of the circuit
that is grounded; for ungrounded circuits, the greatest voltage
between the given conductor and any other conductor of the
circuit.
70
Article 250 Grounding & Bonding
71
250.1 Scope
This article covers general requirements for grounding
and bonding of electrical installations, and specific
requirements.
Systems, circuits, and equipment required, permitted, or
not permitted to be grounded.
Circuit conductor to be grounded on grounded systems
Location of grounding connections.
Types and sizes of grounding and bonding conductors and
electrodes.
Methods of grounding and bonding.
Conditions under which guards, isolation or insulation may
be substituted for grounding.
72
250.8 Connection of Grounding and Bonding Equipment
Prohibits the use of sheet metal screws as a means for
attaching equipment grounding conductors to equipment.
Connection means that are listed, are part of listed
equipment, or are exothermically welded are required to
ensure a permanent and low-resistance connection
73
250.8 Update
(A)Permitted Methods
Grounding conductors and bonding jumpers shall be
connected by one of the following means:
1. Listed pressure connectors
2. Terminal bars
3. Pressure connectors listed as grounding and bonding
Equipment
4. Exothermic welding process
5. Machine screw-type fasteners that engage not less than
two threads or are secured with a nut
6. Thread-forming machine screws that engage not less than
two threads in the enclosure
7. Connections that are part of a listed assembly
1"
10x32 self tapping screw
74
250.8 Update
Non Permitted Methods
Connection devices or fittings that depend solely on solder
shall not be used. This applies to interior water piping
constructed using solder.
Sheet metal screws shall not be used to connect grounding
conductors to enclosures.
75
250.8 Update
In this cut away example, the KaKu foot plate of the ODU
included grounding screw has produced almost 3 full
machine type screw threads in the metal.
A self-tapping sheet metal screw, which is commonly
found in hardware stores, will not comply with the NEC®
standard. In this example only, a single thread is formed.
76
250.10 Protection of Ground Clamps and Fittings
Ground clamps or other fittings shall be approved for general use
without protection or shall be protected from physical damage as
indicated in (1) or (2).
1) In installations where they are not likely to be damaged.
2) Where enclosed in metal, wood, or equivalent
protective covering.
77
250.12 Clean Surfaces
Nonconductive coatings, such as paint, lacquer, and enamel,
on equipment to be grounded should be removed from
threads and other contact surfaces to ensure good electrical
continuity or be connected by means of fittings designed so
as to make such removal unnecessary.
78
250.28 Main Bonding Jumper
For a grounded system, an un-spliced main bonding jumper
shall be used to connect the equipment grounding
conductor(s) and the service-disconnect enclosure to the
grounded conductor of the system within the enclosure for
each service disconnect.
Construction: Where a main bonding jumper is a screw
only, the screw shall be identified with a green finish that
shall be visible with the screw installed
79
250.50 Grounding Electrode System
Section 250.50 introduces the important concept of a “grounding
electrode system,” in which all electrodes are bonded together,
as illustrated in Exhibit 250.50.
Rather than relying totally on a single electrode to perform its
function over the life of the electrical installation, the NEC®
encourages the formation of a system of electrodes “if
available on the premises.”
There is no doubt that building a system of electrodes adds a
level of reliability and helps ensure system performance over a
long period of time.
80
250.50 Grounding Electrode System
Example, Exhibit 250.50
A grounding electrode system that uses the metal frame of a
building, a ground ring, a concrete- encased electrode, a metal
underground water pipe, and a ground rod.
81
250.52 Grounding Electrodes
(A) Electrodes Permitted for Grounding
82
1.
Metal Underground Water Pipe: A metal underground water
pipe in direct contact with the earth for 3.0 m (10 ft) 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 insulating
pipe) to the points of connection of the grounding electrode
conductor and the bonding conductors.
2.
Metal Frame of the Building or Structure: The metal frame of
the building or structure, where effectively grounded.
3.
Concrete-Encased Electrode: An electrode encased by at
least 50 mm (2 in.) of concrete, located within and near the
bottom of a concrete foundation or footing that is in direct
contact with the earth. Reinforcing bars shall be permitted to
be bonded together by the usual steel tie wires or other
effective means.
250.52 Grounding Electrodes
(A) Electrodes Permitted for Grounding
83
3.
Ground Ring: A ground ring encircling the building or
structure, in direct contact with the earth, consisting of at
least 6.0 m (20 ft) of bare copper conductor not smaller than
2 AWG.
4.
Rod and Pipe Electrodes: Rod and pipe electrodes shall not
be less than 2.5 m (8 ft) in length and shall consist of the
following materials.
1. Electrodes of pipe or conduit shall not be smaller than
metric designator 21 (trade size 3/4) and, where of iron or
steel, shall have the outer surface galvanized or otherwise
metal-coated for corrosion protection.
Technician Scenario 8:
Grounding Decision
84
Grounding Decision
Your job is to draw a line representing the ground bonding wire
from the ground block to the proper grounding location. Your
decision is based on NEC® sections 250.8, 250.52 (A)(1) as well
as the “20ft” rule (Section 800.40).
Purpose of this drawing is to illustrate
“Grounding
& Bonding” all other specific
installation requirements are outlined in
the DIRECTV New Hire Training Progam
v
Service
Panel
85
250.52 Grounding Electrodes
(A) Electrodes Permitted for Grounding
86
5.
Rod and Pipe Electrodes: Rod and pipe electrodes shall not
be less than 2.5 m (8 ft) in length and shall consist of the
following materials.
a) Electrodes of pipe or conduit shall not be smaller than
metric designator 21 (trade size 3/4) and, where of iron or
steel, shall have the outer surface galvanized or otherwise
metal-coated for corrosion protection.
6.
Plate Electrodes: Each plate electrode shall expose not less
than 0.186 m² (2 ft2) of surface to exterior soil.
a) Electrodes of iron or steel plates shall be at least 6.4 mm
(1/4 in.) in thickness. Electrodes of nonferrous metal shall
be at least 1.5 mm (0.06 in.) in thickness.
250.52 Grounding Electrodes
6.
87
Other Local Metal Underground Systems or Structures: Other
local metal underground systems or structures such as
piping systems and underground tanks.
250.52 Grounding Electrodes
(B) Electrodes Not Permitted for Grounding
The following shall not be used as grounding electrodes:
1. Metal underground gas piping system
2. Aluminum electrodes
88
250.70 Methods of Grounding and Bonding
Conductor Connection to Electrodes.
89
The grounding or bonding
conductor shall be connected
to the grounding electrode by
exothermic welding, listed lugs,
listed pressure connectors,
listed clamps, or other listed
means.
Connections depending on
solder shall not be used.
Ground clamps shall be listed
for the materials of the
grounding electrode and the
grounding electrode conductor
and, where used on pipe, rod,
or other buried electrodes,
shall also be listed for direct
soil burial or concrete
encasement.
Not more than one conductor
shall be connected to the
grounding electrode by a single
clamp or fitting unless the
clamp or fitting is listed for
multiple conductors
One of the following methods
shall be used:
A pipe fitting, pipe plug, or
other approved device
screwed into a pipe or pipe
fitting.
A listed bolted clamp of
cast bronze or brass, or
plain or malleable iron.
For indoor
telecommunications
purposes only, a listed
sheet metal strap-type
ground clamp having a rigid
metal base that seats on the
electrode and having a
strap of such material and
dimensions that it is not
likely to stretch during or
after installation.
An equally substantial
approved means.
250.92 Services
(A) Bonding of Services
1.
90
Intended to clarify where metal raceways, boxes, or
enclosures contain a grounding electrode conductor. Both
ends of the raceway, box, or enclosure must be bonded to
the grounding electrode conductor.
a) Bonding the raceway to the conductor reduces the
impedance and minimizes the potential difference
between the electrical equipment and ground.
250.94 Bonding for Other Systems
An accessible means external to
enclosures for connecting intersystem
bonding and grounding conductors
shall be provided at the service
equipment and at the disconnecting
means for any additional buildings or
structures by at least one of the
following means:
1. Exposed nonflexible metallic
raceways
2. Exposed grounding electrode
conductor
3. Approved means for the
external connection of a
copper or other corrosionresistant bonding or
grounding conductor to the
grounded raceway or
equipment
4. FPN
91
Technician Scenario 9:
Potential Difference
92
Potential Difference
The technician has line of sight on the east side of the
house. The solitary outlet is on the east side of the
house. An external service equipment enclosure is on
the east side of the house and services the air
conditioning unit.
93
Potential Difference
Can we attach to the “service enclosure” on/for the AC unit
under NEC 250.94?
Ask yourself, how is the service enclosure grounded?
The AC unit service enclosure is not compliant because of
what factors?
94
Article 800 Communications Circuits
95
800.1 Scope
Article 800 covers telephone, telegraph (except radio), outside
wiring for fire alarm and burglar alarm, and similar central station
systems; and telephone systems not connected to a central
station system but using similar types of equipment, methods of
installation, and maintenance.
96
800.40 Cable and Primary Protector Grounding
The metallic member (s) of the cable sheath, where required to be
grounded by 800.33, and primary protectors shall be grounded as
specified in 800.40(A) through (D).
(A) Grounding Conductor
Length: The primary protector grounding conductor shall be as
short as practicable. In one- and two-family dwellings, the
primary protector grounding conductor shall be as short as
practicable, not to exceed 6.0 m (20 ft) in length.
Run in Straight Line: The grounding conductor shall be run to
the grounding electrode in as straight a line as practicable.
97
800.100 Cable and Primary Protector Grounding
The primary protector and the metallic member (s) of the cable
sheath shall be grounded as specified in 800.100(A) through (D).
(A) Grounding Conductor
Length: The primary protector grounding conductor shall
be as short as practicable. In one-and two-family dwellings,
the primary protector grounding conductor shall be as
short as practicable, not to exceed 6.0 m (20 ft) in length.
FPN: Similar grounding conductor length limitations
applied at apartment buildings and commercial buildings
help to reduce voltages that may be developed between the
building’s power and communications systems during
lightning events.
Run in Straight Line: The grounding conductor shall be run
to the grounding electrode in as straight a line as
practicable.
98
Technician Scenario 10:
LOS & Grounding Location
99
LOS & Grounding Location
“You are driving up that country driveway toward the
home where you are going to install DIRECTV. As it
comes into view, what first thoughts come to mind in
regards to the important job variables you must
consider?”
100
LOS & Grounding Location
The number one technician response is “Line of Sight”
Let’s expand on your answer.
You should think of both LOS and…“Where is the grounding
point?”
The cable (ground block) must come to within 20ft of the
grounding electrode system in order to make the installation
compliant with the National Electric Code.
So…this may ultimately change our choice of ODU mounting
location.
101
Article 810
Radio and Television Equipment
102
810.1 Scope
Article 810 covers antenna systems for radio and television
receiving equipment, amateur radio transmitting and receiving
equipment, and certain features of transmitter safety. This article
covers antennas such as multi-element, vertical rod, and dish,
and also covers the wiring and cabling that connects them to
equipment. This article does not cover equipment and antennas
used for coupling carrier current to power line conductors.
Article 810 covers wiring requirements for television and radio
receiving equipment, specifically including digital satellite
receiving equipment for television signals, and wiring for amateur
radio equipment.
103
810.3 Other Articles
Wiring from the source of power to and between devices connected
to the interior wiring system shall comply with Chapters 1 through
4 other than as modified by Parts I and II of Article 640. Wiring for
audio signal processing, amplification, and reproduction
equipment shall comply with Article 640. Coaxial cables that
connect antennas to equipment shall comply with Article 820.
104
810.4 Community Television Antenna
The antenna shall comply with this article. The distribution
system shall comply with Article 820.
105
810.15 Grounding
Masts and metal structures supporting antennas shall be
grounded in accordance with 810.21.
106
810.16 Size of Wire-Strung Antenna — Receiving Station
(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.
They 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.
107
810.18 Clearances - Receiving Stations
Underground conductors shall be
separated at least 12" from conductors
of any light or power circuits.
4” Separation of attached lead-in
power line conductors and coaxial
cable.
6’ Separation of lightening arrest
systems and coaxial cables.
Purpose of this drawing is to illustrate
Clearances all other specific installation
requirements are outlined in the DIRECTV
New Hire Training Program
4" Separation of attached power
line conductors and coaxial
cable
72" (6') Separation of
lightening arrest system
and coaxial cable
108
12" Underground
Separation of
power line and
coaxial cable
810.18 Clearances - Receiving Stations
The clearance between
lead-in conductors and
any conductor forming a
part of a lightning rod
system shall not be less
than 1.8 m (6 ft) unless the
bonding referred to in
250.60 is accomplished.
Underground conductors
shall be separated at least
300 mm (12 in.) from
conductors of any light or
power circuits or Class 1
circuits.
109
Underground conductors shall be separated
at least 12" from conductors of any light or
power circuits.
4” Separation of attached lead-in power
line conductors and coaxial cable.
6’ Separation of lightening arrest systems
and coaxial cables.
Purpose of this drawing is to illustrate
Clearances all other specific installation
requirements are outlined in the DIRECTV
New Hire Training Program
4" Separation of attached power
line conductors and coaxial
cable
72" (6') Separation of
lightening arrest system
and coaxial cable
12" Underground
Separation of
power line and
coaxial cable
810.20 Antenna Discharge Units — Receiving Stations
A. Where Required
Each conductor of a lead-in from an outdoor antenna
shall be provided with a listed antenna discharge unit.
Exception: Where the lead-in conductors are enclosed
in a continuous metallic shield that either is
permanently and effectively grounded or is protected
by an antenna discharge unit.
B. Location
Antenna discharge units shall be located outside the
building or inside the building between the point of
entrance of the lead-in and the radio set or transformers
and as near as practicable to the entrance of the
conductors to the building.
110
810.21 Grounding Conductors - Receiving Stations
C. Material
The grounding conductor shall be of copper, aluminum,
copper-clad steel, bronze, or similar corrosion-resistant
material. Aluminum or copper-clad aluminum grounding
conductors shall not be used where in direct contact with
masonry or the earth or where subject to corrosive
conditions.
Where used outside, aluminum or copper-clad aluminum
shall not be installed within 450 mm (18 in.) of the earth.
111
810.21 Grounding Conductors - Receiving Stations
D. Supports
The grounding conductors shall be securely fastened in
place and shall be permitted to be directly attached to the
surface wired over without the use of insulating supports.
112
810.21 Grounding Conductors - Receiving Stations
E. Run in Straight Line
The grounding conductor for an antenna mast or antenna
discharge unit shall be run in as straight a line as
practicable from the mast or discharge unit to the
grounding electrode.
113
810.21 Grounding Conductors - Receiving Stations
F. Electrode
The grounding conductor shall be connected as follows:
1. To the nearest accessible location on the following:
a. The building or structure grounding electrode system as
covered in 250.50
b. The grounded interior metal water piping systems, within 1.52
m (5 ft) from its point of entrance to the building, as covered
in 250.52
c. The power service accessible means external to the building,
as covered in 250.94
d. The metallic power service raceway
e. The service equipment enclosure, or
f. The grounding electrode conductor or the grounding
electrode conductor metal enclosures; or
2. If the building or structure served has no grounding means, as
described in 810.21(F)(1), to any one of the individual electrodes
described in 250.52
3. If the building or structure served has no grounding means, as
described in 810.21(F)(1) or (F)(2), to an effectively grounded
metal structure or to any of the individual electrodes described
in 250.52.
114
810.21 Grounding Conductors - Receiving Stations
G. Inside or Outside Building
The grounding conductor shall be permitted to be run
either inside or outside the building.
H. Size
The grounding conductor shall not be smaller than 10
AWG copper, 8 AWG aluminum, or 17 AWG copper-clad
steel or bronze.
I. Common Ground
A single grounding conductor shall be permitted for both
protective and operating purposes
J. Bonding of Electrodes
115
A bonding jumper not smaller than 6 AWG copper or
equivalent shall be connected between the radio and
television equipment grounding electrode and the power
grounding electrode system at the building or
structure served where separate electrodes are used.
Technician Scenario 11:
17 AWG CCS
116
17 AWG CCS
Technician arrives at a formal installation to find
no dual coaxial cable with copper clad steel
messenger used for bonding of the ODU footplate.
117
17 AWG CCS
Can the technician attach a separate 17 AWG CCS
messenger wire to the existing coaxial run?
The NEC code is concerned about bonding the ODU mount
and mast to the residential ground source: there is nothing
that prohibits attaching the 17 AWG CCS messenger to the
coaxial cable.
If zip ties are used, black colored are recommended for
outdoor use and they should be staggered at unequal
distances to…
Zip ties should not be tight or should avoid compromising
the integrity of the…
118
Article 820
Community Antenna Television
and Radio Distribution Systems
(CATV)
119
820.1 Scope
This article covers coaxial cable distribution of radio
frequency signals typically employed in community antenna
television (CATV) systems.
Article 820 covers the installation of coaxial cable for the
distribution of radio frequency (RF) signals associated with
closed-circuit television, cable television, and security
television cameras. This article also covers interior coaxial
cable for radio and television receiving equipment.
120
820.33 Grounding of Outer Conductive Shield of a
Coaxial Cable
The outer conductive shield of the coaxial cable shall be
grounded at the building premises as close to the point of cable
entrance or attachment as practicable.
For purposes of this section, grounding located at mobile home
service equipment located in sight from, and not more than 9.0 m
(30 ft) from, the exterior wall of the mobile home it serves, or at a
mobile home disconnecting means grounded in accordance with
250.32 and located in sight from and not more than 9.0 m (30 ft)
from the exterior wall of the mobile home it serves, shall be
considered to meet the requirements of this section.
121
820.40 Cable Grounding
Where required by 820.33, the shield of the coaxial cable shall
be grounded as specified in 820.40(A) through (D).
A. Grounding Conductor
1) Insulation: The grounding conductor shall be insulated and
shall be listed as suitable for the purpose.
2) Material: The grounding conductor shall be copper or other
corrosion-resistant conductive material, stranded or solid.
3) Size: The grounding conductor shall not be smaller than 14
AWG. It shall have a current-carrying capacity approximately
equal to that of the outer conductor of the coaxial cable. The
grounding conductor shall not be required to exceed 6 AWG.
4) Length: The grounding conductor shall be as short as
practicable. In one- and two-family dwellings, the grounding
conductor shall be as short as practicable, not to exceed 6.0 m
(20 ft) in length.
5) Run in Straight Line: The grounding conductor shall be run to
the grounding electrode in as straight a line as practicable.
122
820.42 Bonding and Grounding at Mobile Homes
A. Grounding
Where there is no mobile home service equipment located in
sight from, and not more than 9.0 m (30 ft) from, the exterior wall
of the mobile home it serves or there is no mobile home
disconnecting means grounded in accordance with 250.32 and
located within sight from, and not more than 9.0 m (30 ft) from,
the exterior wall of the mobile home it serves, the coaxial cable
shield ground, or surge arrester ground, shall be in accordance
with 820.40(B)(2).
123
820.42 Bonding and Grounding at Mobile Homes
(B) Bonding
The coaxial cable shield grounding terminal, surge arrester
grounding terminal, or grounding electrode shall be bonded to
the metal frame or available grounding terminal of the mobile
home with a copper grounding conductor not smaller than 12
AWG under any of the following conditions:
(1) Where there is no mobile home service equipment or
disconnecting means as in 820.42(A).
(2) Where the mobile home is supplied by cord and plug.
124
820.42 Bonding and Grounding at Mobile Homes
125
820.42 Bonding and Grounding at Mobile Homes
TRAILER FRAME FROM ABOVE
HERE ONLY
GND CONNECT TO
BREAKER BOX
BEST ON THIS
I-BEAM
NOT HERE THOUGH ( ON THE HORIZ. RUNNERS)
126
820.49 Fire Resistance of CATV Cables
Coaxial cables installed as wiring within buildings shall be
listed as being resistant to the spread of fire in accordance
with 820.50 and 820.51.
820.50 Listing, Marking, and Installation of Coaxial
Cables.
Coaxial cables in a building shall be listed as being suitable for
the purpose, and cables shall be marked in accordance with
Table 820.50. The cable voltage rating shall not be marked on
the cable.
127
820.51 Additional Listing Requirements
Cables shall be listed in accordance with 820.51(A)
through (D).
1. Type CATVP: Type CATVP community antenna television
plenum cable shall be listed as being suitable for use in
ducts, plenums, and other spaces used for environmental
air and shall also be listed as having adequate fireresistant and low smoke-producing characteristics.
2. Type CATVR: Type CATVR community antenna television
riser cable shall be listed as being suitable for use in a
vertical run in a shaft or from floor to floor and shall also
be listed as having fire-resistant characteristics capable of
preventing the carrying of fire from floor to floor.
128
820.52 Installation of Cables and Equipment
A. Separation from Other Conductors
1. Other Applications. Coaxial cable shall be separated at
least 50 mm (2in) from conductors of any electric light,
power, Class 1, non-power-limited fire alarm, or medium
power network-powered broadband communications
circuits
Exception No. 1: Where either…
1. All of the conductors of electric light, power, Class 1,
non–power-limited fire alarm, and medium power networkpowered broadband communications and circuits are in a
raceway, or in metal-sheathed, metal-clad, nonmetallicsheathed Type AC or Type UF cables, or
2. All of the coaxial cables are encased in raceway.
129
820.100 Cable Grounding
The shield of the coaxial cable shall be grounded as specified in
820.100(A) through (D).
(A) Grounding Conductor
1. Insulation: The grounding conductor shall be insulated and
shall be listed.
2. Material: The grounding conductor shall be copper or other
corrosion-resistant conductive material, stranded or solid.
3. Size: The grounding conductor shall not be smaller than 14
AWG, have a current-carrying capacity approximately equal to
that of the outer conductor of the coaxial cable, and should
not be required to exceed 6 AWG.
130
820.100 Cable Grounding
4.
Length: In one- and two-family dwellings, the grounding
conductor shall be as short as practicable, not to exceed 6.0
m (20 ft) in length.
Run in Straight Line. The grounding conductor shall be run
to the grounding electrode in as straight a line as practicable.
Physical Protection: The grounding conductor shall be
protected where exposed to physical damage. Where the
grounding conductor is run in a metal raceway, both ends of
the raceway shall be bonded to the grounding conductor or
the same terminal or electrode to which the grounding
conductor is connected.
131
Practical Use
Ground Strap
Copper on Copper
Galvanized on
Galvanized
Installed in such away as
to avoid loosening
Bonding wire
insulation removed
and bent in a
clockwise direction to
allow multiple
points of contact as
shown
132
Practical Use
Split Bolt
To be used to bond the #10 copper bond wire to the primary
ground #6 copper or # 6 braided copper
Corner Clamps
Can not be used on a service/meter door
Can not impede access to the equipment inside the
enclosure
Must fit securely
Can not be removed by hand
Pipe Clamps
Clamp must be identified for the size of pipe
Single wire use
Copper on Copper
Galvanized on Galvanized
133
Practical Use
Screw Down Attachments
Switches, Splitters, Ground Blocks are for single wire use
only
Ground Screws
Mounted in ODU foot plate
If the proper size hole is not present a drill bit of proper size
must be used
Self forming machine thread
Must form at least two threads into the metal housing
Green in color (used for QC audit verification)
Single wire use
134
Practical Use
135
Pole Mount
Installing a fine thread screw on
a pole used for pole mounting is
not compliant
If a screw is used, the bonding
wire would contact the pole at
two points; the top and the
bottom.
Attaching the bonding wire with
an existing bolt would not be
compliant.
Currently, the only approved
method for bonding a pole
mount is to attach the #17 AWG
bonding wire at the pole using a
ground strap.
NEC Code Adoption Map
This map represents those state adoptions of the NEC code by
year as of August 2009.
136
For more information, use the following internet link: schneider-electric.us