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Chapter 8 Flashcards

1
Q

ac

A

Alternating Current
A current flow that alternates
periodically (usually sinusoidal)
in magnitude and direction.
TDMM.* Page G-7

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2
Q

BBC

A

Backbone Bonding Conductor
A conductor that is intended to
equalize potentials between TRs
on the same floor of a structure
where multiple TBBs are used in
a multi-story building. Formerly
referred to as the grounding
equalizer (GE).
TDMM.* Page 8-20

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3
Q

Bonding

A

The connection intended to
safely and effectively equalize
the potential differences
between two metallic items.
TDMM.* Page 8-1

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4
Q

dc

A

Direct Current
Current flow that has a constant
direction. The letters dc are also
used generically to refer to any
constant waveform or signal
(e.g., a battery voltage of 3 volts
direct current [Vdc]).
TDMM.* Page G-58

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5
Q

EMC

A

Electromagnetic Compatibility
The ability of equipment to
function in a manner that makes
them immune to certain amounts
of electromagnetic interference
(EMI), while keeping the
interference generated by them
within specific limits.
TDMM.* Page G-67

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6
Q

EMI

A

Electromagnetic Interference
Radiated or conducted
electromagnetic energy that has
an undesirable effect on
electronic equipment or signal
transmissions.
TDMM: G-67

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7
Q

GEC

A

Grounding Electrode Conductor
The conductor used to connect the
grounding (earthing) electrode to
either the equipment grounding
(earthing) conductor, or to the
grounded conductor of the circuit
at the service equipment, or at the
source of a separately
derived system.
TDMM.* Page 8-5

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8
Q

GPR

A

Ground Potential Rise
A voltage difference between a
grounding electrode system and
the earth return currents
produced by a lightning strike or
a power fault current.
TDMM: Page G-87

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9
Q

Grounding

A

The establishment of a
reference for the electrical
power source (ac or dc), the
electrical equipment, or both.
TDMM.* Page 8-1

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10
Q

IG

A

Isolated Ground
An equipment grounding
(earthing) topology that
presumably reduces the effects
of EMI and RFI on the equipment
grounding (earthing) system.
TDMM.* Page 8-10

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11
Q

Impedance

A

The total opposition of electrical
current in ac circuits or an ac
waveform imposed upon a dc or
ac circuit or conductor.
TDMM.* Page 8-8

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12
Q

Lightning Exposure

A

An outdoor telecommunications
cable’s susceptibility to
electrical power system faults or
to lightning or other transients.
TDMM.* Page 8-26

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13
Q

PBB

A

Primary Bonding Busbar
The dedicated extension of the
building ac grounding (earthing)
electrode system for the
telecommunications
infrastructure. Formerly referred
to as the telecommunications
main grounding busbar (TMGB).
TDMM.* Page 8-17

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14
Q

RFI

A

Radio Frequency Interference
Electromagnetic interference
(EMI) in the radio frequency (RF)
spectrum. The source may be
any object (artificial or natural)
that carries rapidly changing
electrical currents or generates
RF, such as an electrical
circuit or the sun.
TDMM.* Page G-158

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15
Q

SBB

A

Secondary Bonding Busbar
The grounding (earthing)
connection point for
telecommunications
infrastructure systems and
telecommunications equipment
in the area being served by an
ER or TR. Formerly referred to as
the telecommunications
grounding busbar (TGB).
TDMM.* Page 8-18

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16
Q

SBG

A

Supplementary Bonding Grid
A set of conductors or conductive
elements formed into a grid or
provided as a conductive plate that
becomes part of the bonding
network to which it is
intentionally attached.
TDMM: Page G-788

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17
Q

TBC

A

Telecommunications Bonding
Conductor
A conductor that interconnects the
telecommunications bonding
infrastructure to the building s
service equipment (power) ground.
Formerly referred to as the bonding
conductor for telecommunications
(BCT).
TDMM.* Page G-792

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18
Q

Zone of Protection

A

Area under or nearly under a
lightning protection system.
TDMM.* Page 8-26

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19
Q

What term describes the
establishment of a
reference for the electrical
power source (ac or dc),
the electrical equipment,
or both?

A

Grounding
TDMM.* Page 8-1

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20
Q

What term describes the
connection intended to
safely and effectively
equalize the potential
differences between two
metallic items?

A

Bonding
TDMM.* Page 8-1

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21
Q

What is a “foreign”
electrical voltage
or current?

A

Electrical voltages or currents
that are not normally carried by,
or expected in,
the telecommunications
distribution system
TDMM.* Page 8-2

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22
Q

Name 4 potential negative
consequences of having a
foreign voltage or current
travel through the
telecommunications
distribution system.

A

1 .Death or injury due to electrical
shock
2.Destruction of electronic
equipment and property due to
electrical fire
3.Component malfunction or
degradation
4.Work or process disruption
TDMM.* Page 8-2

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23
Q

Name 6 factors the ICT
designer must consider
when designing the
bonding infrastructure for a
telecommunications
distribution system.

A

1.Lightning
2.Ground potential rise (GPR)
3.Contact with electrical power circuits
4.EMI
5.RFl
6.EMC
TDMM.* Page 8-2

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24
Q

True or False
The ICT designer is not
responsible for engineering
the portions of electrical
system related to ac
electrical ground faults, air
terminal lightning protection
systems, or surge protection.

A

True. The ICT designer is not
responsible for engineering the
portions of electrical system
related to ac electrical ground
faults, air terminal lightning
protection systems, or surge
protection.
TDMM: Page 8-3

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25
When is the best time to design a bonding, grounding (earthing), and protection scheme for a structure?
During the initial planning and construction phases of a project TDMM.* Page 8-3
26
How should the ICT designer seek to resolve a conflict between a local safety code and the manufacturer's requirements?
Ask the AHJ to resolve the conflict before proceeding. TDMM.* Page 8-3
27
Name the 3 subsystems that constitute a bonding and grounding (earthing) system.
1 .ac grounding electrode systems 2.Equipment grounding (earthing) system 3. Telecommunications bonding infrastructure TDMM.* Page 8-4
28
What is the purpose of the ac grounding (earthing) electrode system?
Establishes a 0 V reference for ac electrical power systems, whether utility-provided or customer-derived Provides a path for the dissipation of currents due to lightning or accidental contact with higher- voltage systems Provides a path for the dissipation of electrostatic discharge currents TDMM.* Page 8-5
29
Name the 2 main components of the ac grounding (earthing) electrode system.
1 .Grounding electrode conductor (GEC) 2.Grounding (earthing) electrode TDMM.* Page 8-5
30
Which component of the ac system can be used to connect the grounding (earthing) electrode the equipment grounding (earthing) conductor?
The GEC, which can also be used to connect to the grounded conductor of the circuit at the service equipment or at the source of a separately derived system TDMM.* Page 8-5
31
What device within the ac grounding (earthing) electrode system is used to establish an electrical connection to the earth?
Grounding (earthing) electrode TDMM.* Page 8-5
32
Why does the ICT distribution designer need to identify the type of ac grounding (earthing) electrode system used for the building's ac electrical system?
To make an effective bonding connection for the grounding (earthing) busbars and other telecommunications points within the TRs TDMM.* Page 8-6
33
Where are telecommunications busbars installed when building steel is used as a grounding (earthing) electrode?
On or as close as practicable to a structural steel member within the ER, TR, or EF TDMM.* Page 8-6
34
True or False The ICT distribution designer should bond the telecommunications bonding infrastructure to the building's metallic water pipes whenever possible.
False. While it is permissible to use a building's metallic water pipes for bonding, they should be used with caution. Maintenance and upgrades are generally performed with nonconductive plastic pipes. For this reason, if used, metallic water pipes should never be a single ground (earth) source. TDMM.* Page 8-6
35
Typically, who is responsible for specifying the test criteria for the verification of the ac grounding (earthing) electrode
Qualified electrical designer TDMM.* Page 8-7
36
When should the ac grounding electrode be tested?
After the cabling and telecommunications grounding (earthing) infrastructure are installed but prior to either the final approval of the telecommunications bonding infrastructure or end-user telecommunications equipment installation TDMM.* Page 8-7
37
What is the best possible reading for any bonding conductor when measuring ac current?
0 A TDMM.* Page 8-7
38
What is the recommended maximum ac current value on any bonding conductor?
Less than 1 A TDMM.* Page 8-7
39
What is the recommended maximum dc current value on any bonding conductor?
Less than 500 mA TDMM.* Page 8-7
40
What should be done if testing reveals an abnormally high ac current level on a bonding conductor?
A qualified electrical maintenance individual should be called immediately. TDMM.* Page 8-7
41
What type of tester is used for two-point bonding measurements?
Earth grounding (earthing) resistance tester that is configured for a continuity test TDMM.* Page 8-7
42
What is the recommended bonding resistance between the nearest available grounding (earthing) electrode and the busbar in the EF?
0.1 ohms (100 milliohms) TDMM.* Page 8-7
43
What is the acceptable bonding resistance between the nearest available grounding (earthing) electrode and the busbar in the EF of a central office facility?
Less than 100 milliohms, possibly 50 milliohms TDMM.* Page 8-7
44
What is the primary purpose of the telecommunications equipment grounding (earthing) system?
To enhance personnel safety and reduce the likelihood of a fire hazard by facilitating the operation of overcurrent devices (circuit breakers) TDMM.* Page 8-8
45
What is the main component of the telecommunications equipment grounding (earthing) system?
Equipment grounding (earthing) conductor TDMM.* Page 8-8
46
What term is used to describe the total opposition of electrical current in ac circuits or an ac waveform imposed on a dc or ac circuit or conductor?
Impedance TDMM: Page 8-8
47
Name 2 forces that influence the impedance of an electrically conductive path.
1. lnductive reactance 2. Capacitive reactance TDMM.* Page 8-8
48
What are the recommended maximum impedance values for telecommunications equipment grounding (earthing) conductors in the United States?
1 ohm for ac circuits of 120 V to ground and 0.8 ohms for 277 V to ground TDMM: Page 8-9
49
Name 3 negative consequences that may occur if the impedance of an ac electrical circuit exceeds its recommended maximum value.
1 .Equipment operator could be exposed to a prolonged electrical shock, which may be fatal. 2. The equipment or structure could catch on fire. 3.Equipment may malfunction repeatedly. TDMM: Page 8-9
50
What instrument is used to measure the impedance of the telecommunications equipment grounding (earthing) conductor?
Ground impedance tester TDMM: Page 8-9
51
True or False Most ground impedance testers can be used to uncover improper wiring conditions.
True. Test personnel can use most ground impedance testers to uncover most improper wiring conditions. TDMM.* Page 8-9
52
What is the presumed benefit of using an isolated ground?
Reduces the effects of EMI and RFI on the equipment grounding (earthing) system) TDMM.* Page 8-10
53
Name 2 ways that isolation ground receptacles can be identified.
1 .With a solid orange receptacle coloring 2.With a beige receptacle coloring marked with an orange triangle on the face TDMM.* Page 8-70
54
An IG system is NOT recommended for use for in customer premises voice and data systems. Why?
Because its use may defeat the purpose of an equipotential plane that is desired for all EFs, ERs, and TRs TDMM.* Page 8-10
55
What is the purpose of a supplementary bonding grid (SBG)?
To provide a low-impedance path between many cabinets or racks of telecommunications equipment TDMM.* Page 8-70
56
What is the overall purpose of the telecommunications bonding infrastructure?
To equalize potentials between metallic surfaces predominantly in the event of lightning, ac electrical system faults, electromagnetic induction, or electrostatic discharge TDMM.* Page 8-12
57
Where do telecommunications bonding and grounding begin in a small ER or EF?
At the PBB TDMM.* Page 8-13
58
Which component serves as the central attachment point for all telecommunications bonding and grounding (earthing) connections in a small system?
PBB TDMM.* Page 8-13
59
What are the minimum dimensions of a PBB?
=6.3 mm (0.25 in) thick by -101.6 mm (4 in) wide, and variable in length TDMM.* Page 8-17
60
Why should the PBB be located as near as possible to the telecommunications cable EF?
Because surge currents need to be equalized before they penetrate the telecommunications infrastructure TDMM.* Page 8-17
61
What is the intended purpose of a TBC?
To bond the PBB to the ac grounding (earthing) electrode system via the ac main service entrance panelboard TDMM.* Page 8-17
62
What is the purpose of an SBB?
To serve as the grounding (earthing) connection point for telecommunications infrastructure systems and telecommunications equipment in the area served by an ER or TR TDMM.* Page 8-18
63
What are the minimum dimensions of an SBB?
=6.3 mm (0.25 in) thick by mm (2 in) wide, and variable in length TDMM.* Page 8-18
64
Why should the SBB be referenced to the telecommunications ground terminal of the nearest ac electrical panelboard?
To equalize the potentials during lightning, electrostatic discharge, and EMI conditions TDMM.* 8-19
65
What is a TBB?
The TBB is a TBC that is intended to equalize potentials between TRs on multiple floors or multiples TRs on the same floor of a building with an ultimate connection to the EF's PBB. TDMM.* Page 8-79
66
What is the relationship between impedance and length of a TBB?
Impedance increases with the length, which reduces the TBB's ability to equalize potentials between ERs, TRs, TEs, and EFs. TDMM.* Page 8-79
67
What is an alternative method to using a TBB in the system for a large site?
Specify that the SBB in each TR be bonded to the structural steel if present and to the nearest ac electrical panelboard. TDMM.* Page 8-79
68
Which component is intended to equalize potentials between TRs on the same floor of a structure where multiple TBBs are used?
Backbone bonding conductor (BBC) TDMM.* Page 8-20
69
What is the minimum recommended size for a bonding conductor if its run will not exceed -30.5 m (100 ft)?
6 AWG TDMM.* Page 8-20
70
How is the maximum resistance value for a conductor length calculated?
By dividing 40 V by the short- time rating of the ac GEC TDMM.* Page 8-21
71
Name 2 typical methods for making bonding connections.
1 .Bolts or crimps 2.Exothermic welding TDMM.* Page 8-22
72
Name 3 factors that make it difficult to determine the integrity of a telecommunications bonding connection.
1 .Distance 2.Access 3.Existence of other parallel bonding connections TDMM.* Page 8-23
73
Name 4 types of problems that can be revealed by visually inspecting a telecommunications bonding connection.
1 .Loose connections 2. Corrosion 3. Physical damage 4. System modifications TDMM.* Page 8-23
74
What type of bonding method may be useful for cable trays when the mechanical integrity of the connection is questionable?
The conventional method of bonding across sectional and angle brackets TDMM.* Page 8-25
75
Why should the use of home runs of telecommunications bonding conductors within cable trays be avoided?
To prevent varying lengths of telecommunications bonding conductors within the cable trays from becoming a source of voltage and, ultimately, amperage due to impedance differences TDMM.* Page 8-25
76
True or False Using direct-buried cable eliminates risk of (lightning) exposure.
False. In general, a choice of direct-buried cable does not eliminate exposure. TDMM.* Page 8-26
77
Why is electrical power cable routed above aerial cable?
To intercept and divert direct lightning strikes TDMM.* Page 8-26
78
What term is used to describe an outdoor telecommunications cable's susceptibility to electrical power system faults or to lightning or other transients?
Exposure TDMM.* Page 8-26
79
When is telecommunications cable considered electrically exposed?
When any of its branches or individual circuits are exposed TDMM.* Page 8-26
80
What term is used to describe the area under or nearly under a lightning protection system?
Zone of protection TDMM.* Page 8-26
81
What term is used to refer to a simplified zone of protection?
Cone of protection TDMM.* Page 8-26
82
Name the 5 factors used to estimate loss due to lightning (as listed in NFPA 780).
1 . Type of structure & construction 2.Relative location 3.Lightning strike consequences 4.Occupancy & contents 5.Lightning frequency TDMM.* Page 8-27
83
What steps should the ICT distribution designer take when cable exposure is in question?
*Consider it exposed. *Note it as exposed in the request for quote response. TDMM.* Page 8-28

MJ Class (23 decks)

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