Types of Cable Installations in Electrical Network

What is the main advantage of open-wire construction for power distribution cables?

• Low initial cost

• High reliability

• Less space required

• Greater safety

What is a disadvantage of aerial cables compared to open-wire construction?

• High susceptibility to mechanical damage

• More susceptible to lightning effects

• Increased hazard with crane use

• Require proper vertical clearances

What type of cables are suitable for relatively short distances with spans in the range of 100-150 feet?

• Self-supporting cable

• Messenger-supported cable

• Rigid steel conduit systems

• Underground ducts

What is the main advantage of underground ducts for cable installations?

• Easy detection and repair of damage

• Greater resistance to lightning effects

• High degree of safety and mechanical protection

• Low initial cost

What type of cables are used where it is necessary to provide a high degree of safety and mechanical protection?

• Open-wire cables

• Underwater (Submarine) cables

• Aerial cables

• Above-ground conduits

What is a characteristic of direct-buried cables in the ground?

• Readily added to or maintained

• Lower current carrying capacity than cables in ducts

• Require frequent backfilling

• Resistant to moisture and soil contaminants

When is submarine cable used in electrical networks?

• In areas with high mechanical protection

• For overhead power distribution

• For short distances with low current

• When no other cable system can be used

What is the main purpose of grounding the shields and metallic sheaths of power cables?

• To increase the current carrying capacity

• To reduce the insulation thickness

• To prevent rapid degradation of the jacket

• To provide a fault return path in case of insulation failure

How should the grounding conductor be attached to the shield or metallic sheath of power cables?

• By welding

• By soldering

• By twisting

• By clamping

What is the advantage of grounding the cable shield lengths at both ends?

• Reduces the duty on the shield

• Increases the fault current

• Requires thicker insulation

• Causes rapid degradation of the jacket