RCDD Grounding, Bonding, and Electrical Protection 3

Question 1

What type of bonding conductor must be used to connect metallic cable tray sections together?

Accepted Answer

A jumper wire or splice plate listed for the purpose

Answer

Standard electrical wire nut

Answer

Cable shield drain wire

Answer

Copper tape wrapped around the joint

Question 2

In a telecommunications room, all metallic equipment racks should be:

Accepted Answer

Bonded to the TGB using appropriately sized bonding conductors

Answer

Left isolated to prevent ground loops

Answer

Connected only to the building structural steel

Answer

Bonded together in a daisy chain without connection to TGB

Question 3

What is the purpose of a protector 'heat coil' (also called a heat arrestor)?

Accepted Answer

To disconnect a cable pair when excessive current causes it to melt, preventing fire

Answer

To warm cables in cold environments to prevent ice damage

Answer

To increase heat dissipation in dense patch panels

Answer

To trigger an alarm when cable temperatures exceed safe limits

Question 4

What is the recommended maximum length for a bonding conductor between a telecommunications rack and the TGB?

Accepted Answer

As short as practicable, typically not exceeding 4 m (13 ft)

Answer

No limit if conductor is properly sized

Answer

Maximum 10 m (33 ft)

Answer

Maximum 15 m (50 ft)

Question 5

Why is it important to isolate the telecommunications grounding system from the AC power grounding system except at the single interconnection point?

Accepted Answer

To prevent noise currents from AC power circuits from circulating in the telecommunications ground path

Answer

To comply with FCC Part 68 requirements for signal isolation

Answer

To allow separate fault detection for each system

Answer

To reduce the number of conductors required in the telecommunications room

Question 6

A telecommunications system designer is reviewing a building's grounding system and finds that the building uses a Ufer ground (concrete-encased electrode). What advantage does this provide?

Accepted Answer

Ufer grounds offer very low impedance due to the large concrete mass in contact with earth

Answer

Ufer grounds are required for all fiber optic systems

Answer

Ufer grounds eliminate the need for a TMGB

Answer

Ufer grounds provide AC power backup during outages