Week 17 Chapter 8 - Pages 8-1 - 8-28

Question 1

It is permissible to use metallic water pipes as a single ground (earth) source.

a. True
b. False

Answer 1

False

p 8-6

Metallic water piping should be used with great caution since maintenance and upgrades are generally performed with nonconductive plastic pipes. If used, metallic water pipes should never be a single ground (earth) source.

Question 2

The secondary bonding busbar (SBB) must be a predrilled copper busbar with holes for use with standard-sized lugs. The minimum thickness for a SBB is:

a. 6mm (0.25 in)
b. 12.5 mm (0.50 in)
c. 19.1 mm (0.75 in)
d. 25.4 mm (1.00 in)

Answer 2

a. 6mm (0.25 in)

Question 3

All sites have bonding conductors that exhibit some value ___ than ___ due to improperly wired electrical outlets, faulty equipment, and induction of ac and dc currents on telecommunications cable shields.

a. Less than 1 A
b. Less than 0 A
c. Greater than 500 mA
d. Greater than 0 A

Answer 3

d. Greater than 0 A

p 8-7: A reading of 0 A is the best possible reading for any bonding conductor. However, all sites have bonding conductors that exhibit some value greater than 0 A due to improperly wired electrical outlets, faulty equipment, and induction of ac and dc currents on
telecommunications cable shields.

Question 4

Generally speaking, ___ is the establishment of a reference for the electrical power source (ac or dc), the electrical equipment, or both.

a. Grounding
b. Equalizations
c. Bonding

Answer 4

a. Grounding

Question 5

Which one of the following systems typically the responsibility of the ITS distribution designer?

a. ac grounding electrode system
b. Equipment grounding system
c. Telecommunications circuit protectors

Answer 5

c. Telecommunications circuit protectors

Question 6

The recommended maximum dc current value on any bonding conductor should be:

a. Greater than 0 A
b. 0 A
c. Less than 500 mA
d. Less than 1 A

Answer 6

c. Less than 500 mA

Question 7

The PBB must be a pre-drilled copper busbar with holes for use with standard-sized lugs, have minimum dimensions of ≈6.3 mm (0.25 in) thick by ___ wide.

a. 25.4 mm (1.00 in)
b. 50.8 mm (2.00 in)
c. 101.6 mm (4 in)
d. 152.4 mm (6 in)

Answer 7

c. 101.6 mm (4 in)

Question 8

The equipment grounding (earthing) system is the portion of the ac electrical distribution that maintains 0 volts (V):

a. On all equipment enclosures during normal operations.
b. For ac electrical power systems, whether utility-provided or customer-derived.

Answer 8

a. On all equipment enclosures during normal operations.

Question 9

The equipment grounding (earthing) system is the portion of the ac electrical distribution that maintains 0 volts (V):

a. On all equipment enclosures during normal operations.
b. For ac electrical power systems, whether utility-provided or customer-derived.

Answer 9

a. On all equipment enclosures during normal operations.

Question 10

When exposed to lightning, direct-buried cable collects ground strikes within a distance determined by soil resistivity. ____ soil resistance intensifies this problem.

a. High
b. Equalized
c. Non-uniform
d. Low

Answer 10

a. High

Question 11

Which one of the following is NOT used to connect a telecommunications grounding (earthing) or bonding conductor to the telecommunications ground (earthing) electrode?

a. Listed clamps
b. Exothermic weld
c. Listed pressure connectors
d. Steel clamps

Answer 11

d. Steel clamps

Question 12

The equipment grounding (earthing) system is the portion of the ac electrical distribution that acts as the intentional path of fault currents under:

a. Normal operations
b. Ground fault conditions

Answer 12

b. Ground fault conditions

Question 13

The ___ is a telecommunications bonding conductor intended to equalize potentials between TRs on multiple floors of a building with an ultimate connection to the EF’s PBB

a. BBC
b. IG
c. TBB
d. TBC

Answer 13

c. TBB

BBC is is intended to equalize potentials between TRs on the SAME floor of a structure where multiple TBBs are used in a multi-story building.

TBC is intended to bond the PBB to the ac grounding (earthing) electrode system via the ac main service entrance panelboard.

Question 14

To prevent any bonding or grounding (earthing) conductor (regardless of its purpose) from reaching this temperature, all grounding (earthing) or bonding conductors should be calculated to limit the total voltage drop to a maximum of ___ along its entire length.

a. 10 V
b. 20 V
c. 30 V
d. 40 V

Answer 14

d. 40 V

p 8-20

The IAEI calculations are based upon the sizing for the GEC over ≈30.5 m (100 ft). Since the bonding conductor sizing in the NEC is based on these same criteria, it can be assumed that following the same calculations will result in a suitable TBC.

Question 15

One purpose of the ac ground (earthing ) electrode system is to establish a ___ reference for ac electrical power systems, whether utility-provided or
customer-derived.

a. 100 mV
b. 0 V
c. 500 mV
d. 1 V

Answer 15

b. 0 V

Question 16

Junction boxes are a form of the equipment grounding (earthing) conductor:

a. True
b. False

Answer 16

a. True

p 8-8
Equipment grounding (earthing) conductor are available in many forms, including:
• Bare copper conductors.
• Insulated conductors.
• Metallic conduits (e.g., RMC, IMC) and the NRTL-listed fittings.
• ac electrical panelboards and the NRTL-listed fittings.
• Junction boxes.
• Outlet boxes.
• Metallic raceways.

Question 17

In most applications, where any bonding conductor does not exceed ___ , a minimum of a 6 AWG bonding conductor is sufficient for referencing all metallic surfaces within the telecommunications environment.

a. 1 m (3.28 ft)
b. 10 m (33 ft)
c. 30 m (100 ft)
d. 42.7 m (140 ft)

Answer 17

c. 30 m (100 ft)

Question 18

The recommended maximum value for the bonding resistance between the busbar in the EF to TR is ___ :

a. 500 milliohms
b. 0.1 ohms
c. 1.00 ohms
d. 0.5 ohms

Answer 18

b. 0.1 ohms

p 8-23

The recommended maximum value for the bonding resistance between these two points is 0.1 ohms (100 milliohms). Before performing this test, the test equipment manufacturer should be consulted for detailed instrument setup and safety precautions.

Question 19

The recommended maximum ac current value on any bonding conductor should be:

a. Less than 0 A
b. 0 A
c. Less than 500 mA
d. Less than 1 A

Answer 19

d. Less than 1 A

Question 20

It should be recognized that the impedance of the TBB increases due to the length, thereby reducing its ability to equalize potentials between ERs, TRs, TEs and EFs. This is true at ___ frequencies, but more noticeable at ___ frequencies:

a. Higher, lower
b. Lower, higher

Answer 20

b. Lower, higher

p 8-19: It should be recognized that the impedance of the TBB increases due to the length, thereby reducing its ability to equalize potentials between ERs, TRs, TEs and EFs. This is true at low frequencies (e.g., 60 Hz currents) but more noticeable at higher frequencies (e.g., lightning).

Question 21

Interbuilding telecommunications circuits are considered to have a lightning exposure unless the interbuilding cable runs are _____ or less in length, directly buried, or in underground conduit.

a. 21.3 m (70 ft)
b. 85.4 m (280 ft)
c. 64 m (210 ft)
d. 42.7 m (140 ft)

Answer 21

d. 42.7 m (140 ft)

p 8-26

Interbuilding telecommunications cable runs of ≈42.7 m (140 ft) or less, directly buried or in underground conduit. The shield or conduit must be bonded to the building’s ac grounding (earthing) electrode system at each end. This is another simplified zone of protection, as well as proper bonding practice.

Question 22

NFPA 780 covers lightning protection systems and defines as exposed anything above ground and outside the zone of protection. The zone of protection is an area _____ a lightning protection system.

a. Under or nearly under
b. Nearly under
c. Under

Answer 22

a. Under or nearly under

p 8-26

NFPA 780 covers lightning protection systems and defines as exposed anything above ground and outside the zone of protection (e.g., an area under or nearly under a lightning protection system).

Question 23

One example of an effective means of bonding to racks and cable trays is to run an insulated copper conductor in the cable tray and bond it to every cable tray section in which it is contained.

a. True
b. False

Answer 23

a. True

p 8-25

Question 24

The bonding of a small system’s _____ to the main electrical service panelboard and the structural steel is crucial to providing the best possible design to eliminate hazardous voltages during lightning and system fault conditions.

a. TBB
b. PBB
c. TBC
d. GEC

Answer 24

b. PBB

p 8-13

Question 25

The equipment grounding (earthing) system is also known as the _____ in some countries.

a. Earthing system
b. Telecommunications bonding infrastructure
c. Equipment bonding system
d. ac grounding (earthing) electrode system

Answer 25

c. Equipment bonding system

p 8-4

Equipment grounding (earthing) system (also known as the equipment bonding system in some countries)

Question 26

Generally, the connection intended to safely and effectively equalize the potential differences between two metallic items is the definition of:

a. Grounding
b. Earthing
c. Bonding
d. Equalization

Answer 26

c. Bonding

p 8-1

Question 27

In the case of lightning exposure, direct-buried cable collects ground strikes within a distance determined by soil resistance. This distance is typically:

a. 1.832 m to 9.1 m (6 ft to 30 ft)
b. 1.83 m to 6.1 m (6 ft to 20 ft)
c. 0.9 m to 4.6 m (3 ft to 15 ft)
d. 0.9 m to 3 m (3 ft to 10 ft)

Answer 27

b. 1.83 m to 6.1 m (6 ft to 20 ft)

p 8-26

Direct-buried cable collects ground strikes within a distance determined by soil resistance (typically ≈1.83 m [6 ft] to ≈6.1 m [20 ft]). High soil resistance intensifies this problem.

Question 28

Telecommunications bonding conductors can carry ac ground fault current or lightning strike current?

a. True
b. False

Answer 28

b. False

p 8-12

Telecommunications bonding conductors are not intended to carry ac ground fault current or lightning strike current. However, they are installed so that voltages may be equalized when those events occur.

Question 29

ICT distribution designers are not responsible for engineering the portions of the electrical system related to surge protection.

a. True
b. False

Answer 29

a. True

p 8-3

ICT distribution designers are not responsible for engineering the portions of the electrical system related to ac electrical ground faults, air terminal lightning protection systems (e.g., lightning rods), or surge protection.

Question 30

The impedance of the telecommunications equipment grounding (earthing) conductor should be:

a. Less than 1 A
b. Stable
c. As high as possible
d. As low as possible

Answer 30

d. As low as possible

p 8-9

The impedance of the telecommunications equipment grounding (earthing) conductor should be as low as possible. The NEC has not set a required impedance value.

Question 31

If you have a circuit with 120 volts, 12 amps, and 10 ohms, it has a peak power of _____ watts.

a. 1018
b. 1200
c. 1440
d. 2037

Answer 31

c. 1440

A: 120 x 12 = 1440 W = Peak power

Note: 1440 x 0.707 = 1018 W or average power

The sustainable or usable portion of electrical energy in an alternating current. For sinusoidal signal, it is the peak power (PP) multiplied by .707 (e.g., 100 watts [W] of PP is approximately equal to 71 W of PA). See also power and peak power.

Question 32

Phase difference is the relationship in time between two waveforms of the same:

a. Power
b. Voltage
c. Frequency
d. Current

Answer 32

c. Frequency

p 9-3

Phase difference is the relationship in time between two waveforms of the same frequency.

Question 33

Which of the following is NOT provided by the ac grounding electrode system?

a. Zero volt reference for AC power
b. A path for dissipating electrical current
c. A path for dissipating electrostatic discharge
d. Adequate electrical protection for people and equipment

Answer 33

d. Adequate electrical protection for people and equipment

p 8-5

The ac grounding (earthing) electrode system does not provide adequate electrical protection for people and equipment in the event of electrical faults within the premises wiring system. This is the function of the equipment grounding (earthing) system, which is covered further in this chapter.

Question 34

Certain systems must exist relative to bonding and grounding at every site. Which of the following is NOT the responsibility of the ICT distribution designer?

a. AC grounding electrode system (e.g., in some countries it may also be known as the earthing system)
b. Telecommunications bonding infrastructure
c. Lightning protection system
d. Equipment grounding system (e.g., in some countries it may also be known as the equipment bonding system)

Answer 34

c. Lightning protection system

p 8-4

Question 35

Electrical power cables are usually routed above aerial cable in order to:

a. Provide aesthetics, as the power cables are bigger than the aerial cables
b. Be a strength member in case a tree or something heavy falls on the lines
c. Negate the need for protectors
d. Intercept and divert direct power strikes

Answer 35

d. Intercept and divert direct power strikes

p 8-26

Electrical power cable is usually routed above aerial telecommunications cable to intercept and divert direct lightning strikes. This helps but does not negate the need for protectors.

Question 36

Which of the following covers lightning protection systems and defines as exposed anything above ground and outside the zone of protection?

a. NTSB-12
b. IEEE 1100
c. NFPA 780
d. NEC 47

Answer 36

c. NFPA 780

p 8-26

NFPA 780 covers lightning protection systems and defines as exposed anything above ground and outside the zone of protection (e.g., an area under or nearly under a lightning protection system).

Question 37

An isolated ground receptacle may be identified by:

a. Beige coloring with an orange triangle on the face
b. The letters IG
c. Continuous orange coloring
d. Either a or c

Answer 37

d. Either a or c

p 9-19

IG receptacles can be identified with a continuous orange receptacle coloring or beige receptacle marked with an orange triangle upon its face.

Question 38

Surge currents due to lightning and other sources MUST be _____ before they penetrate the infrastructure.

a. Shorted
b. Maximized
c. Terminated
d. Equalized

Answer 38

d. Equalized