Chapter 8 - Bonding and Grounding

Question 1

Grounding

Answer 1

the establishment of a reference for the electrical power source. (AC or DC, the electrical equipment or both)

Question 2

Bonding

Answer 2

the connection intended to equalize, safely and effectively, the potential differences between two metallic items. (eg a telecom grounding busbar and a metallic cable tray)

Question 3

The ITS distribution designer usually is responsible for the telecom bonding and grounding and the telecom circuit protectors. (True/False)

Answer 3

True

Question 4

Three subsystems constituting the bonding and grounding system

Answer 4

ac Grounding Electrode System
Equipment Grounding System
Telecommunications Bonding Infrastructure

Question 5

What is the purpose of an ac Grounding Electrode System?

Answer 5

• Establish a 0 volt (V) reference for ac electrical power systems, whether utility-provided or customer derived
• Provide a path for the dissipation of currents due to lighting or accidental contact with higher voltage systems
• Provide a path for the dissipation of electrostatic discharge

Question 6

ac Grounding Electrode System is made up of what two main components

Answer 6

• Grounding electrode conductor (GEC) - The conductor used to connect the grounding electrode to either the equipment conductor or to the grounded conductor of the circuit at the service equipment.
• Grounding Electrode - a conductor, usually a rod, pipe or plate, in direct contact with the earth. It established an electrical connection to the earth.

Question 7

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

Answer 7

Equipment bonding system

Question 8

The ICT designer must recognize that which three subsystems constituting the bonding and grounding (earthing) system should be placed at every site?

Answer 8

• ac grounding (earthing) electrode system
• equipment grounding (earthing) system
• telecommunications bonding infrastructure

Question 9

A standard Secondary Bonding Busbar (SBB) should have a minimum width of ____ and minimum depth of ____ with a variable length.

Answer 9

Minimum width of 2in
Minimum depth of 0.25in thick

Question 10

The ___ is a conductor that is intended to equalize potentials between TRs on the same floor of a structure.

Answer 10

BBC

Question 11

The Primary Bonding Busbar (PBB) must be bonded to what?

Answer 11

• Telecommunications Bonding Backbone (TBB)
• Equipment
• ac grounding (earthing) electrode system via the ac main service entrance panelboard and telecommunications bonding conductor (TBC)
• PBB can be bonded to several other telecommunications components

Question 12

The secondary bonding busbar (SBB) is bonded to what?

Answer 12

Either the telecommunications equipment ground terminal of the nearest ac electrical panelboard and building steel
or the telecommunications bonding backbone (TBB)

Question 13

True or False
The telecommunications bonding backbone (TBB) is absolutely necessary.

Answer 13

False
The TBB is not an absolute necessity. As an alternative, the ICT designer can specify that the SBB in each TR be bonded to structural steel if present and to the nearest ac electrical panelboard. Each of the bonding connections should be tested to verify that a low-resistance connection exists.

Question 14

True or False
The backbone bonding conductor (BBC) is not needed if electrically continuous structural steel is bonded to the building’s grounding electrode system, and testing indicates this connection is sufficient to equalize potential across all telecommunications spaces.

Answer 14

True

Question 15

The primary bonding busbar (PBB) is minimum of ____ wide, and ___ deep.

Answer 15

4in W
0.25in depth

Question 16

The secondary bonding busbar is a minimum of ___ W and ___ depth.

Answer 16

2in W
0.25in depth

Question 17

The telecommunications bonding conductor (TBC) is at a minimum size of ___.

Answer 17

6 AWG.
The TBC at minimum is the same size as the largest telecommunications bonding backbone (TBB).

Question 18

The backbone bonding conductor should be installed where?

Answer 18

Every third floor for large systems.

Question 19

What is the recommended maximum ac current value on any bonding conductor?

Answer 19

Should be less than 1A, with a recommended max dc current value to be less than 500mA.

Question 20

The equipment grounding (earthing) system is the portion of the ac electrical distribution that serves what three purposes?

Answer 20

• It maintains 0V on all equipment enclosures during normal operations
• It acts as the intentional path for fault current under ground fault conditions
• Properly installed and maintained, it provides a voltage reference for end user telecommunications electronic equipment power supplies in order to stabilize bit pulses and steady state timing of internal circuitry

Question 21

The telecommunications equipment grounding (earthing) system impedance is dependent on what physical characteristics?

Answer 21

• Tightness of telecommunications equipment grounding conductor terminations
• Length of telecommunications equipment grounding conductor
• Number of bends in the telecommunications grounding conductor
• size of the telecommunications equipment grounding conductor
• radius of each bend in the telecommunications equipment grounding conductor path