Grounding

1
Grounding Bonding

• ELCM 247 Module D

2
Grounding and Bonding

• Two principles govern the need for robust
  grounding and bonding practices.
• Safety (Personal, Public Property)
• Network Performance (Noise)

3
A Closer Look atGrounding and Bonding

• Standards from the following organizations are
  the four main sources for information about
  grounding and bonding codes and practices
• Canadian Electrical Code (CEC Section 10)
• ANSI/EIA/TIA-607 Commercial Building Grounding
  and Bonding for Telecommunications
• Underwriters Laboratories UL-497 Protectors for
  Paired Conductor Communication Circuits
• IEEE Standard 142-1991 Grounding of Industrial
  and Commercial Power Systems

4
A Closer Look atGrounding and Bonding

• Grounding, Bonding, and Effective Ground
• a) A ground is a conducting connection between an
  electrical circuit and the earth, or a conducting
  body

5
Grounding and Bonding

• b)Bonding is the permanent joining of metallic
  parts to form a conductive path that ensures
  electrical continuity and safely conducts
  current.
• c) An effective ground is an intentional
  connection to a low-resistance earth ground that
  permits current to discharge into the earth
  without buildup of hazardous voltages on the
  cable, equipment, or people

6
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• When designed and installed following the
  appropriate codes, specifications, and safety
  practices, the grounding and bonding network
  components create a system that effectively
  safeguards personnel, property, and equipment
• The most common hazard in grounding and bonding
  networks is electric shock, which occurs from
  accidental contact with energized devices
• The effects of electrical shock are determined by
  the magnitude of current and duration of the shock

7
(No Transcript)
8
A Closer Look atGrounding and Bonding

• Every building has a grounding electrode, a
  conductor that provides a direct, low-resistance
  connection to the earth
• A grounding conductor connects the electrical
  equipment to the grounding electrode and the
  building's main grounding busbar
• The main grounding busbar is a conductor that
  serves as a common connection point for two or
  more circuits the busbar is solid copper with
  insulated standoffs

9
(No Transcript)
10
A Closer Look atGrounding and Bonding

• Telecommunications circuit protectors are used to
  protect telecommunications facilities and
  equipment from abnormally high voltages and
  currents. This protection is in addition to the
  requirements and recommendations for grounding
  and bonding telecommunications systems
• Underground trunking cables are not considered
  exposed but are considered protected from
  lightning and electrical distribution.

11
A Closer Look atGrounding and Bonding

Perhaps the greatest threat To OSP facilities
12
A Closer Look atGrounding and Bonding

• The tremendous voltages inherent in lightening
  bolts give cause for great concern and fear.
• Essentially the release of potential energy
  through living objects cause fluids within to
  boil and explode the body containing them.

13
A Closer Look atGrounding and Bonding

• The greatest threat from lightening to
  communications systems in realized in Outside
  Plant components.
• OSP proximity to Power Transmission exposes its
  components to similar damage potential.
• Telecom Towers, Arial Cable and Building Masts
  are examples of high risk components.

14
A Closer Look atGrounding and Bonding

• We know the devastating effect lightening can
  have on living objects, but what is the risk to
  communication equipment?
• Where ever there lightening not far away in
  moisture in the air.
• Precipitation is well known to cause fading in
  wireless path transmission.
• Moisture in the form of water, ice and snow can
  also cause great damage to telecom
  infrastructure.

15
A Closer Look atGrounding and Bonding

• Water entry to splice points and access
  terminals will cause corrosion to metallic parts.
  
• The result is noise or unwanted signal
  interfering with a transmission.
• Static or noise can become stronger in level
  completely masking an intelligent signal.
• Noise basically attenuate signal strength.
• We hear the result as a crackle sound (analog) or
  measure corrupt data (digital)

16
A Closer Look atGrounding and Bonding

• The Canadian Electrical Code if the foremost
  authority on GB requirements in Canada.
• Understanding Ohm law helps appreciate the risk
  associated with electrical shock.
• High voltage and some resistance for short
  duration can be fatal.
• Milliamps of current can cause critical muscle
  reactions

17
A Closer Look atGrounding and Bonding

• Mitigating the effects of unwanted voltages from
  our transmission in of paramount importance.
• All OSP work spaces should be tested prior to
  entry with approved and calibrated voltage
  detectors.
• If foreign voltage in excess is measured the
  space should not be entered.
• Further, the site should be identified and tagged
  ensuring are aware of the risk potential.

18
A Closer Look atGrounding and Bonding

Non Contact Voltage Detector
19
A Closer Look atGrounding and Bonding

• Section 10 CEC
• Interior wiring should not be exposed to AC
  voltages greater than 150 V
• Two wire DC operating between 50 V and 300 V must
  be grounded
• Circuits less than 50 V must be grounded if.
• Run overhead outside of buildings.
• Where supplied by greater than 150 V

20
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• Every building has a grounding electrode, a
  conductor that provides a direct, low-resistance
  connection to the earth
• A grounding conductor connects the electrical
  equipment to the grounding electrode and the
  building's main grounding busbar
• The main grounding busbar is a conductor that
  serves as a common connection point for two or
  more circuits the busbar is solid copper with
  insulated standoffs

21
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• Conductors used specifically for bonding are
  called bonding conductors the conductor that
  connects the buildings service equipment ground
  to the telecommunications grounding system is
  called the bonding conductor for
  telecommunications (BCT)
• The BCT is a No. 6 AWG (American Wire Gauge) or
  larger insulated copper conductor that connects
  the equipment ground to the telecommunications
  main grounding busbar

22
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• The telecommunications main grounding busbar
  (TMGB) is the foundation of the grounding system
  and it serves as an interface to the buildings
  power
• The TMGB also serves as a central connection
  point for the telecommunications bonding backbone
  (TBB) and equipment
• Usually there is one TMGB per building it is
  typically in the entrance room (facility), the
  building entrance for both public and private
  network service cables, or in the main
  telecommunications room

23
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• In each telecommunications room the
  telecommunications grounding busbar (TGB)
  provides a common access point of connection for
  systems and equipment bonding to ground
• The TGB is built in a similar fashion to the TMGB
  and it should be installed as close as possible
  to the panel board in the telecommunications room
• If a backboard (a panel for mounting system
  hardware and equipment) is located in the same
  room as a TGB, it should be bonded to the TGB

24
(No Transcript)
25
A Closer Look atGrounding and Bonding

• Grounding and bonding network components
• The TMGB and all TGBs are interconnected by a No.
  6 AWG or larger insulated conductor, the TBB
• The TBBs primary function is to reduce or
  equalize differences in the telecommunications
  systems bonded to it it is considered part of
  the grounding and bonding infrastructure, but it
  is independent of all equipment and cable
• The TBB begins at the TMGB and extends throughout
  the building, using the telecommunications
  backbone pathways

26
A Closer Look atGrounding and Bonding

• When planning TBB installation, the following
  design considerations are important
• Be consistent with the design of the
  telecommunications backbone cabling system
• Use multiple TBBs if the building size permits
  it, but they must be bonded together at the top
  floor
• Bonding conductors between a TBB and TGB must be
  continuous and routed as directly as possible
• Dont use interior water pipe systems or metallic
  cable shields as a TBB

27
Grounding and BondingSystem vs. Equipment

• A building has six types of grounding and bonding
  systems designed to provide overall protection
  for the building and its occupants
• Lightning protection system
• Grounding electrode system
• Electrical bonding and grounding system
• Electrical power protection system
• Telecommunications bonding and grounding system
• Telecommunications circuit protector system

28
Grounding and BondingSystem vs. Equipment

• Grounding systems
• Lightning protection systems provide a designed
  path for lightning current to travel
• Lightning protection systems are made up of
  several components air terminals (lightning
  rods) conductors ground terminations (ground
  rods) surge arresters and surge protectors
• The telecommunications ground must be bonded to
  the lightning protection system within 3.7 meters
  of the base of the building

29
(No Transcript)
30
Grounding and BondingSystem vs. Equipment

• Grounding systems (cont.)
• Grounding electrode systems are the end product
  of bonding together all metal underground water
  pipes, the metal frame of the building, any
  electrode that is encased in concrete, any ground
  ring, and any made or other electrodes
• Other electrodes include rod and pipe electrodes,
  plate electrodes, and metal underground systems
• Grounding electrode system forms a single,
  reliable ground for a building

31
Grounding and BondingSystem vs. Equipment

• Grounding systems (cont.)
• Both the electrical bonding and grounding systems
  and the electrical power protection system refer
  to the requirements for all electrical
  installations, such as types, sizes, methods and
  locations of conductors and connections
• Three scientific principles guide bonding
  conductors equalization, diversion, and coupling
• The type of bonding conductors used in most
  commercial buildings depends on the application
  and the fault-current-carrying capacity needed

32
(No Transcript)
33
Grounding and BondingSystem vs. Equipment

• Equipment grounding
• Each type of grounding equipment has its own set
  of grounding and bonding specifications
• The primary purpose of equipment grounding is to
  remove potentially dangerous voltages it also
  protects against electrical shock and prevents
  heat building up in the equipment
• Earth grounding is an intentional connection from
  a circuit conductor to a ground electrode placed
  in the earth and it provides a safe path for the
  dissipation of fault currents

34
Grounding and BondingSystem vs. Equipment

• Equipment grounding (cont.)
• The grounding conductor should be bonded to the
  nearest accessible earth-ground
• The bonding jumper must be no smaller than AWG 6
  copper, it must be connected between the
  communications system grounding electrode and the
  buildings power grounding electrode system
• Termination is the connection of a cable to
  connecting hardware the earth ground must
  terminate to the grounding electrode using either
  exothermic welding, listed lugs or clamps, or
  listed pressure connector

35
The process of exothermic welding is a method of
making electrical connections of copper to copper
or copper to steel in which no outside source of
heat or power is required.
(Outside Heating application)
36
Grounding and BondingSystem vs. Equipment

• Equipment grounding (cont.)
• An intrinsically safe system operates by
  preventing ignition of flammable or combustible
  material under normal or abnormal conditions
• The primary advantage of intrinsically safe
  systems is that ordinary wiring is allowed
• Intrinsically safe systems are composed of safe
  interconnecting cables, cable shields,
  enclosures, cable trays, and raceways all items
  must be grounded with an equipment grounding
  electrode, and bonded with an approved method
• Intrinsically safe definition
• http//en.wikipedia.org/wiki/Intrinsic_safety

37
Cable Protection and Equipment-Grounding Practices

• Inside cable and wire is that which runs from
  communications equipment to the protector
• All types of inside communication cables and
  wires must be rated for resistance to the spread
  of fire, be suitable for the installation site,
  and have a voltage rating of at least 300 volts
  the conductors in these cables, other than fiber,
  must be copper
• Specific installation requirements include the
  separation of communications cables and
  electrical power cabling using approved fire
  stopping methods proper conduit use

38
Cable Protection and Equipment-Grounding Practices

• Inside cable and wire (cont.)
• When using an unshielded backbone cable, a TBB
  conductor should be used with it the TBB must be
  bonded to the grounding using the grounding
  busbar nearest the termination point of the cable
• The shields of shielded cable are usually
  grounded at one end to a connector panel, which
  must be bonded to the closest approved ground
• In smaller equipment rooms, equipment is usually
  grounded via the closest ground larger buildings
  with multiple equipment rooms require multiple
  TGBs

39
(No Transcript)
40
Telecommunications Circuit Protectors

• A telecommunications circuit protector is a
  device that protects telecommunications
  facilities and equipment from abnormally high
  voltages and current
• High voltage and currents are usually caused by
  exposure to lightning, accidental contact with
  electrical light, or power conductors operating
  at over 300 volts to ground
• There are three types of telecommunications
  circuit protectors primary secondary and data
  and fire alarm

41
Telecommunications Circuit Protectors

• Primary protectors are most typically made from
  carbon blocks, gas tubes, or solid state
• When ready to install, follow these installation
  practices they should be installed immediately
  adjacent to the exposed cables point of
  entrance for long-term reliability, ensure that
  the installation is in a noncorrosive atmosphere
  adequate lighting is very important when
  installed in a metal box, bond the box with a
  grounding conductor directly to the protectors
  ground when installed outside, use cabinets,
  boxes and mounting hardware

42
(No Transcript)
43
Telecommunications Circuit Protectors

• Secondary protectors are typically made from heat
  coil, sneak-current fuse, or PTC resistors
• Secondary protectors must coordinate with the
  lightning transient and power-fault requirements
  of primary protection
• For this reason, secondary protectors often
  include primary protection device materials, and
  secondary protection is usually available as an
  option on primary protectors
• Secondary protectors must handle sneak current
• Sneak current protection The application of a
  protective device that is intended to limit
  currents too small to operate fuse links, stub
  cables, or the fuse of a fused primary protector.

44
How Documentation Helps You and Your Network

• The advantages of keeping documentation
• It serves as a comprehensive reference
• It allows for easier additions, moves, and
  changes to equipment and workstations
• It can be a valuable source when troubleshooting
• It can provide the necessary justification for
  adding staff or equipment
• It provides proof that the installation meets a
  manufacturers hardware or software requirements
• It makes security management more effective

45
A Spark Gap

• A spark gap consists of an arrangement of two
  conducting electrodes separated by a gap usually
  filled with a gas such as air. When a suitable
  voltage is supplied, a spark forms, ionizing the
  gas and drastically reducing its electrical
  resistance. An electric current then flows until
  the path of ionized gas is broken or the current
  reduces below a minimum value called the holding
  current.
• Protected cabling installations may utilize a
  spark gap to provide a path bypass or shunt to
  ground.

46
Chapter Summary

• All telecommunications systems require grounding
  and bonding systems. Several associations provide
  codes, standards, and minimum requirements for
  installing these systems. ANSI/EIA/TIA-607,
  Commercial Building Grounding and Bonding
  Requirements for Telecommunications, is the
  primary source of installation information. The
  second most important source is the Canadian
  Electrical Code

47
Chapter Summary

• A grounding and bonding network is made up of
  insulated copper conductors. These conductors are
  run in parallel with the telecommunications
  cables, and link rooms containing
  telecommunications equipment to a common ground.
  The recommended size for these conductors range
  from No. 6 to No. 3 /0 AWG insulated copper

48
Chapter Summary

• These conductors are bonded to solid copper
  grounding bus bars, which are installed in the
  entrance facility, the main telecommunications
  room, and all other telecommunications rooms. In
  addition to the conductors that run throughout
  the building, telecommunications equipment,
  frames, cabinets, raceways, and protectors are
  grounded to the bus bars
• Central office and cellular sites should not
  exceed 5 ohm of resistance as measured between
  the TMGB and the Grounding Electrode.

49
Chapter Summary

• The bus bars throughout the building are bonded
  together with a backbone cable of at least No. 6
  AWG insulated copper. This backbone cable is also
  connected to the main grounding busbar, which is
  bonded to the electrical service (power) ground
  and an earth ground

50
Chapter Summary

• Telecommunications circuit protectors are used to
  protect telecommunications facilities and
  equipment from abnormally high voltages and
  currents. This protection is in addition to the
  requirements and recommendations for grounding
  and bonding telecommunications systems
• Underground trunking cables are not considered
  exposed but are considered protected from
  lightning and electrical distribution.

51
Review Questions

• Name two suitable grounding electrodes at
  customer premises?
• Describe the purpose of a spark gap?
• Which principle of electronics describes the
  objective of central office bonding and
  grounding?
• Name six grounding and bonding system for a
  typical building?
• Describe the problem static causes to
  communication systems?
• In reference to the above question list steps
  technicians can take to mitigate this problem?