Network Cabling Systems

1. Network Cabling Systems Power Protection, Grounding and Bonding 1

2. Ground 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.’ NEC Article 100 2

3. Bonding Bonding ‘The permanent joining of metallic parts to form an electrically conductive path that will ensure electrical continuity and the capacity to conduct any fault current that is likely to be imposed.’ NEC Articles 100 and 250-70 3

4. Electrical Noise (Revisited) 4

5. Electromagnetic Induction Principle: Magnetic flux lines crossing a conductor will induce current. There must be relative motion. The quantity of lines that cross the conductor over a period of time will determine the induced current. The direction of the current is based on the polarity and direction of the flux lines. 5

6. EMF, EMR, EMI, RFI and EMP EMF and EMR: Electro-Magnetic Field and Electro-Magnetic Radiation, generally describes the strength of a magnetic field and its ability to induce current. May also refer to Electro-Motive Force (Voltage) EMI and RFI: Electro-Magnetic Interference and Radio Frequency Interference describe undesired, induced electrical current. RFI applied to higher frequencies. EMP: Electro-Motive Pulse which is a sudden but short-lived increase in EMI or RFI. Often destructive. EMP sources include electrical storms and weapons. 6

7. Ambient Noise Ambient Noise: Background, steady, predictable noise. Measuring the frequency of the noise may help determine the source. 60Hz = lighting, motors, electrical appliances, electrical cabling, transformers, etc… 100Hz to 20 MHz = switching power supplies, electronic devices, telephone systems, video, etc… > 20MHz = radio transmitters, cellular telephones, etc… The most common source of ambient noise is the building’s electrical system 7

8. Transient Noise Transient Noise: Irregular and unpredictable noise. Transient noise is often difficult to pinpoint. Likely sources are switching circuits, such as Elevators, photocopiers, welders, electrical storms, static electricity, switching high-current devices, etc… 8

9. Crosstalk Noise where within a bus or cable, one signal-bearing conductor induces a signal on an adjacent conductor. Utilize standards-based cable and connections to reduce the effects of crosstalk Alien Crosstalk is when a signal transfers from another adjacent communication cable. 9

10. Reducing the Effect of Noise Distance: Magnetic flux lines are less dense with distance from the source Reduce the length of cables Shielding: Use shielded cable to either protect it from EMR, or reducing its emissions of EMR. Use metal conduits Other: Use proper cabling techniques 10

11. Grounding and Shielding 11

12. Effective Grounding 12

13. Grounds An earth ground is a point or conductor that has zero electrical potential. A common ground is a reference point for signals. Grounds are important for circuit operation and for safety. They must be properly configured and used. Most systems maintain several levels of grounds. 13

14. Ground Types There are 3 basic types of grounds in electrical systems: Earth ground: primary role is safety. It is also the absolute reference point for voltage. The potential of an earth ground is considered 0 Volts. Chassis ground: usually used for safety and for noise shielding. Meant to have a potential of 0 Volts. Common ground: a point of reference for signals and voltages on the circuit board. Often a relative reference point for voltage. 14

15. Ground Impedance The primary consideration for an effective ground system is maintaining low impedance, especially low resistance. 15

16. Resistance of Conductors Conductor resistance in circular copper conductors 16

17. Ground Loops Ground Loops are multiple paths to ground. Ground loops interfere with the effectiveness of a ground. The different grounds may be at different potential, drawing current through the shield. The voltage reference may not be at 0 Volts 17

18. Modern Building Grounds Large buildings often need more than one earth ground Even within the same building, voltage differences can exist between equipment 18

19. Ground Potential Difference Ground potential differences cause data communications problems. Here is an example: 19

20. Reducing Ground Problems Follow proper grounding practices Maintain separate grounds for those devices that may create noise problems. Maintain low impedance ground connections and conductors. Maintain separation from sources of EMI/RFI and ESD. Do not create ground loops (connections between grounds) near or through cables or cable shields*. Ground cable at one end only*. Ground the cable to chassis ground, not signal ground. Maintain separate electrical outlets for data communications equipment. 20

21. Electrostatic Discharge Static Electricity Humans can feel about 3000 volts Movements such as lifting a foot or moving a chair can generate charges of 1000 volts Computer components can be destroyed or degraded by charges at 10 volts or lower. 21

22. Golden Rules of Static Control Ground yourself and your equipment (wrist straps and mats) Do not ground yourself when working near high voltage sources. Don’t let anyone touch you when working on boards, etc. Transport electronic components and cards in static-shielding bags Keep static-inducing non-conductors such as styrofoam away from electronics 22

23. Electrical Issues 23

24. Electrical Basics 3 wires system in North America Neutral is wider slot The neutral is connected to earth ground at the transformer Forms the return path for current Hot wire is narrower slot The Hot is connected to the transformer Current and voltage source Ground is the round hole The Ground is connected to the building ground Must not carry current under normal conditions 24

25. Overview - Brownouts Decreases in voltage Reductions can be 3% to 5%, or more Can last a considerable amount of time Back-up Power Supplies and UPS’s (Uninterruptable Power Supplies) are a potential solution 25

26. Overview - Blackouts Complete power outage Back-up Power Supplies and UPS’s are a solution 26

27. Spikes An overvoltage that’s short-lived in nature Last between 0.5 and 100 microseconds Amplitude of over 100% peak line voltage Typically caused by EMPs from high load switching and electrical storms Quality surge suppressors and UPS can offer protection 27

28. Surges Voltage above 110% of the nominal value Lasts seconds or longer Most computer supplies running at 120 volts cannot handle high input voltages for any length of time Quality surge suppressors and UPS’s will offer some protection. 28

29. Oscillation Referred to as “Harmonics” or “Noise” Secondary signal on top of the regular waveform with a magnitude ranging from 15 to 100% of nominal line voltage Causes include power transformers with many different legs and interconnections between “neutral” and “ground” wires 29

30. Reducing Electrical Problems Maintain isolated circuits for data communication equipment The symbol for an isolated ground is an orange triangle. Often the entire receptacle is orange Isolated grounds must be professionally installed Use good quality surge suppressors Surge suppressors often have a limited lifespan Use line filters Consider a UPS for critical systems Variety of options available 30

31. Safety A primary responsibility of the installer is safeguarding personnel, property and equipment from “foreign” electrical voltages and currents. Foreign refers to electrical voltages or currents that are not normally carried by, or expected in, the telecommunications distribution systems. 31

32. Safety The results of such disturbances could be: Death by injury. Destruction of electronic equipment. Down time. Work and/or process degradation. 32

33. Level of Electrical Shock Effects on the body are related to the duration and power of the shock, and the resistance and position of the body. Only 100 to 200 milliamps (0.1 to 0.2 Amps) can be fatal Strong shock can damage to vital organs or respiratory seizure Low level currents can cause injuries or death from involuntary muscle reflex reactions 33

34. Electrical Shock The most common electric shock occurs from inadvertent, accidental contact with energized devices or circuits. Common potential shock hazards to avoid: Working on or near an electrically energize device or cable. Touching a faulty or improperly grounded electrical component. Poor clearance and/or lighting which can lead to inadvertently touching an energized conductor. Using or being near conductive material during a lightning storm. 34

35. Preventing Electrical Shock Until verified and tested always assume equipment is energized. Be especially observant for irregular or abnormal conditions during the construction phase of a project. A lockout system must be implemented. Use prudent electrical safety measures such as insulated rubber gloves for personal protection, and use appropriate test equipment to verify the absence of dangerous voltages on all exposed: Cables Wires Metal 35

36. Common Electrical Accidents Cutting or drilling blindly into a wall Unprotected or exposed electrical system on a construction site Panels, cables, outlets, switches, etc Faulty installation (exposed or unterminated live wires). Assuming a cable is not live Digging into an electrical cable Working too closely to overhead lines Faulty lightning protection Working in lightning storms 36

37. Responsibilities Unless you are a certified electrician it is illegal for you to perform any work on electrical systems. 37

38. Building Entrance 38

39. Two Categories of Communication Cable Electrical Protection Shield and other metallic cable elements: Bond directly to the closest available ground Use approved bonding connectors Conductive communication wires: Employ building entrance protectors 39

40. Building Entrance Protectors ‘Primary Protectors’ protect telecom 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 Data & fire alarm 40

41. 41 ‘Primary protectors’ are most typically made from carbon blocks, glass tubes, or solid state Installed immediately adjacent to the exposed cable’s point of entrance Bond the box with a grounding conductor directly to the protector’s ground Circuit Protectors

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43. Carbon Protection Modules The earliest style available An air gap between carbon elements is adjusted to arc at about 300 volts and send the current to a ground conductor Can short permanently Limited lifespan Still available, but they have been replaced by gas and solid state technologies 43

44. Gas Protection Modules Provide a discharge gap between two electrodes sealed in a ceramic envelope containing inert gases Usually arc at a lower voltage than carbon, providing better protection Generally the same price as carbon but have a much longer lifespan 44

45. Solid State Protection Modules Longest lifespan Solid state construction provides nanosecond response time External failsafe mechanism which permanently grounds the module under sustained high current conditions More expensive but most reliable 45

46. 46 Sneak currents are unwanted currents that find their way into a communication system Secondary protectors are typically made from heat coil, sneak-current fuse, or thermal resistors Secondary protectors must coordinate with the lightning transient and power-fault requirements of primary protection Secondary protectors must handle sneak current Sneak Circuit Protectors

47. Locating Protectors Accessible for maintenance Close to the power service entrance Limit the length of conductors & keep straight Ground the protector panel to nearest grounding electrode system Use #6 ground wire Protect all conductors in the cable Protect both ends of the cable Ground all metal elements of the cabinet/box/chassis Leave space for additions 47

48. UL Standards for Communications Circuit Protectors Primary Protectors (UL 497) as near as possible to where the exposed cable enters the building Secondary Protectors (UL 497A) could be anywhere in the building usually behind primary protectors Data and Fire Alarm Protectors (UL 497B) primary protection against lightning 48

49. Lightning 49

50. Lightning Protection Planning Lightning is somewhat unpredictable. Careful planning is required to protect people, buildings and equipment from damage. Described in detail in ANSI/NFPA 780 TIA/EIA requires a lightning protection system, but this system is not usually the responsibility of the communications system designer A zone of protection surrounds building to intercept, divert, and dissipate strikes A system of equalizing, air and ground conductors make up the building grounding system 50

51. Electrical Exposure Electrical Exposure (Telecommunications) The NEC requires a listed primary protector (at both ends) whenever outside plant cable may be exposed to lightning or electrical power disturbances (Section 800-30a). Electrical Exposure (Building Structure) ANSI/NFPA-780 defines “exposed” as anything outside a “cone of protection.” A Cone of Protection is an area under a nearby lightning protection system. 51

52. Building Exposure Electrical Exposure (Building Structure) ANSI/NFPA-780 describes a simplified zone of protection that can be considered for small building’s “cone of protection.” The simplification allows designers to use straight-line sightings instead of estimating complicated curved-shape zones. 52

53. Determining Exposure to Lightning A cable is exposed to lightning unless any of the following conditions are met: The area experiences 5 or fewer thunderstorm days per year and has earth resistivity of less than 100 meter-ohms The buried cable is less than 140 ft. and has a continuous shield grounded at both ends The cable resides totally within a cone of protection afforded by nearby tall buildings or other tall structures that are grounded 53

54. 54 Lightning protection systems Provide a designed path for lightning current to travel Include several elements: 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 Lightning Protection

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56. Aerial Planning Aerial cable often has a power cable routed above it the power cable may intercept or divert lightning strikes this helps, but does not eliminate the need for protectors 56

57. Buried Cable Planning Susceptibility is determined in part by soil resistance buried cable collects ground strikes within an area determined by soil resistance typically 2-6 m (6-20 ft) high soil resistance intensifies this problem Rule of thumb is to provide a grounding system for buried cable 57

58. Buried Cable and the Zone of Protection Buried cables tend to collect ground strikes The zone of protection becomes smaller underground Metal fences, other cables and structures can deflect strikes into, or out of, this zone 58

59. Grounding 59

60. Grounding Electrode System A grounding electrode is a metallic conductor (rod, pipe, plate, etc.) in contact with the earth The system is a network of connected electrodes The systems sends excess electrical energy to earth ground and establishes a voltage reference for the building Not usually the responsibility of a communications systems designer 60

61. Electrical Bonding and Grounding Metallic panels and raceways are bonded to an equipment grounding conductor Equipment grounding conductors are bonded to the electrical service neutral An equipment grounding conductor is usually co-routed with the “hot” and “neutral” conductors Not usually the responsibility of a communications systems designer 61

62. Types of Grounds 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 62

63. Grounding Choices Direct attachment to the closest point in the building’s electrical service grounding electrode system. Preferred because telecommunications cabling and power cabling must be effectively equalized Select the nearest accessible location to: The building ground electrode system An accessible electrical service ground Metallic service raceway (using an approved bonding connector) Ground electrode conductor Approved external connection on the power service panel 63

64. Grounding Choices Cold and Hot water pipes are a poor choice Pipes connected to a utility water distribution system were the first choice but plastic pipes are now commonly used. In many jurisdictions connections to water pipes for safety grounding is no longer permitted This is because of an increased use of nonmetallic pipe. Caution must be exercised when water pipe is used as an intersystem bonding conductor as there may not be a connection to the ground. 64

65. Grounding Choices Installing a Grounding Electrode Allowed if no electric service exists As a last resort, NEC Article 800-40(b)(3) specifies a minimum 1/2" diameter, 5' ground rod driven completely into the ground. must be 6’ from other, existing, electrodes In many jurisdictions, the installation of a grounding electrode is the exclusive responsibility of an electrician. 65

66. Communications Bonding and Grounding Does not replace the electrical grounding systems 3 basic purposes minimize electrical surge effects and hazards supplements electrical bonding lowers the system ground reference potentials 66

67. Telecommunications Grounding Practices Establishing a suitable telecommunications ground is critical in properly grounding telecommunications equipment. A telecommunications ground is always required, and is typically found in: Telecommunications entrance facility for sites with exposed cable Equipment room Telecommunications closet 67

68. 68 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 Ground Systems

69. 3 Principles forCommunications Grounding - pt. 1 Equalization minimize differences in ground potential use short, direct path with large conductor Diversion bonding conductor is connected to the systems ground at both ends bonding conductors follow communications conductors and can easily divert transients away from the communications conductor 69

70. 3 Principles forCommunications Grounding - pt. 2 Coupling the closer the bonding conductor is to the communications cable, the greater the mutual coupling any combination of these three will usually be of benefit to communications equipment 70

71. Physical Protection: Grounds & Bonds If there is a chance of physical damage to the grounding conductor: Mechanical protection is required Metallic conduit or raceway can be used, but must be bonded on both ends Bonding conductors should be routed with the minimum number of bends Bonding connections should be made directly to the points being bonded Avoid unnecessary connections or splices 71

72. Bonding Connections It is recommended that connectors and splices should be one of the following: Tin-plated copper Copper Copper alloy Note: Copper and alloy connections should be cleaned prior to establishing the connection. Typical connections are made by using: Bolt or crimp connectors, splices, clamps or lugs. Exothermic welding. 72

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74. Bullet Bonds, Clips, and Coins Used with outside plant cables (some indoor) Used is splices, building entrances Sized based on the cable size (pair count) Consist of: a base, a top, and nuts (may also include a shoe) Some have longer teeth 74

75. Additional Bonding Products Copper bond bar - different lengths available - holes and slots for attachment Bonding braid Insulator tubing Diaper wrap for encapsulating splices 75

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77. The 607 Standard 77

78. The 607 Standard ANSI TIA/EIA 607 covers grounding and bonding for telecommunications Canadian Electrical Code published by CSA coordinated product test standards similar, but not identical to, the NEC 78

79. Grounding and Bonding Standards from the following organizations are the four main sources for information about grounding and bonding codes and practices National Electrical Code (NEC) 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 79

80. Protection System Planning Advantages to planning early: better access to installation areas system components can be protected from mechanical and environmental effects improved aesthetics it is generally more cost effective to meet protection requirements during the initial construction 80

81. Bidding and Contracts even if the customer has not requested protection equipment consider including it in your bid if it does not already exist who is responsible for each protection system? every item in the protection system adds value for your customer customers have a right to know what they are getting 81

82. 82 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 manufacturer’s hardware or software requirements It makes security management more effective Documentation

83. Grounding and Bonding Grounding, Bonding, and Effective Ground: A ground is a conducting connection between an electrical circuit and the earth, or a conducting body Bonding is the permanent joining of metallic parts to form a conductive path that ensures electrical continuity and safely conducts current 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 83

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85. Grounding 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 85

86. Busbars Grounding and bonding network components: The TMGB and all TGBs are interconnected by a No. 6 AWG or larger insulated conductor, the TBB The TBB’s 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 86

87. Bonding Conductors Bonding conductors must be copper. To avoid unintentional ground connections, bonding conductors within buildings should be insulated. Bonding conductors must be routed with minimum bends or changes in direction. At least 14 AWG (stranded or solid) for the protectors and shields to the selected ground A minimum 6-AWG (stranded) copper conductor is generally used throughout typical commercial buildings. 87

88. Grounding 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 building’s ground 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 88

89. TMGB Telecommunications Main Grounding Busbar The busbar designated for protectors, must safely carry lightning and power fault currents. It should be positioned adjacent to the protectors and directly between the protectors and the approved building ground for protector operation. 89

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91. TGB Telecommunications Grounding Busbar located in the telecommunications closet must be visibly labeled and physically secure spliced to the TBB with a short bonding conductor 91

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93. Selecting Busbars 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 Don’t use interior water pipe systems or metallic cable shields as a TBB 93

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95. TBB Telecommunications Bonding Backbone conductor which is connected from the TMGB to the TGB in each of the TRs each TBB that reaches a TGB must be bonded to the TBB 6 AWG or larger all of these end at the TMGB must be visibly labeled and physically secure 95

96. Grounding and Bonding 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 building’s 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 96

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98. TIA/EIA 607 - Overview 1 A permanent infrastructure for telecommunications grounding and bonding, independent of the telecommunications cabling Minimum 6 AWG (large as 3/0 AWG) insulated bonding conductors are installed through every major telecommunications pathway (TBB) TBB are directly bonded to a telecommunications grounding busbar 98

99. TIA/EIA 607 - Overview 2 TMGB are directly bonded to the electrical service ground All TBBs end on the TMGB Each TBB should be a continuous conductor from the TMGB to the farthest TGB Intermediate TGB should be spliced to the TBB with a short bonding conductor 99

100. TIA/EIA 607 - Overview 3 Each TGB is also directly bonded to building structural steel and other permanent metallic systems, if close and accessible Each TBB that reaches a TGB location must be bonded to the TGB 100

101. TIA/EIA 607 - Overview 4 TGB and TBB must be visibly labeled and physically secure All of the grounding busbars are used by telecommunications systems installers for their grounding requirements 101

102. TR Telecommunications Rooms In a telecommunications closet, suitable ground options include: Building structural steel. An electrical receptacle box or approved conduit connection. A combination of these that is accessible. An already established communications ground. 102

103. Backbone Cable Protection Cables that are inside a building are not usually considered exposed, but protective measures are occasionally advised High-rise and low-wide buildings and buildings close to substations or heavy industrial facilities Electrical power cable should be physically separated from communications cables 103

104. Backbone Cable Protection communications cables should be routed near the center of the building a lightning protection system is advised exposed cables entering the building should be protected and grounded bonding should be installed along each backbone cable pathway 104

105. Inspection Visual inspection can usually reveal problems, such as: Loose connections. Corrosion. Physical damage. System modifications. Note: During any service work, the installer should visually inspect bonding connections. 105

106. Shielded Cabling Systems coax, twinax, and STP typically grounded through their standard connectors to panel at each end panels are bonded to the nearest approved ground with a direct minimum length cable in the work area the shield finds continuity through the power plug’s ground 106

107. Review 107

108. 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. Another important source is the NEC 108

109. Summary Grounding and Bonding Provide additional safety factors where equipment and people are involved. It protects people from being shocked by voltage potentials. It provides a point of discharge for static electricity. It reduces or eliminates stray voltage and current. Reduce the effects of lightning, static electricity and ground faults Properly grounding the shields of cables can help reduce noise and crosstalk from adjacent cables. 109

110. 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 110

111. Summary These conductors are bonded to solid copper grounding busbars, 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 busbars 111

112. Summary The busbars 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 112

113. 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 Documentation makes your job easier and helps you and your networks work more efficiently 113

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