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

Metallic cable tray sections must be bonded together using listed bonding jumpers or splice plates to ensure electrical continuity throughout the tray system.

Question 2

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

Accepted Answer

Bonded to the TGB using appropriately sized bonding conductors

Answer

All metallic equipment racks in a telecommunications room must be individually bonded to the Telecommunications Grounding Busbar (TGB) to equalize ground potential.

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

A heat coil (heat arrestor) is a thermally-operated fusible element that disconnects a cable pair when prolonged overcurrent heats it past its melt point, preventing cable fires.

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

ANSI/TIA-607 recommends bonding conductors be as short as practicable, and practical guidelines suggest keeping rack-to-TGB runs within 4 meters to minimize impedance.

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

Isolating the telecommunications ground except at one interconnection point prevents AC power noise currents from circulating through sensitive telecom equipment grounds.

RCDD - Registered Communications Distribution Designer Practice Test

RCDD - Registered Communications Distribution Designer Practice Test

RCDD Grounding, Bonding, and Electrical Protection 3