Which of the following is NOT an advantage of the underground system over the overhead system?

Explanation:

Underground vs. Overhead Power Systems

Definition: Power distribution systems can be broadly classified into overhead and underground systems. An overhead system involves power lines that are installed above ground, typically using poles or towers. An underground system, on the other hand, involves cables that are laid below the surface of the ground. Each system has its own advantages and disadvantages, and the choice between them depends on factors such as cost, safety, reliability, and aesthetics.

Correct Option Analysis:

The correct option for the given question is:

Option 4: Tapping for loads and service mains is easier.

This option is NOT an advantage of the underground system over the overhead system. In fact, this is one of the main disadvantages of underground systems. The process of tapping into underground cables for additional loads or service mains is significantly more challenging compared to overhead systems. Here's why:

• Complex Installation: Underground cables are buried beneath the surface, often encased in protective conduits or ducts. To tap into these cables, excavation work is required, which can be time-consuming, labor-intensive, and costly.
• Specialized Equipment: Unlike overhead lines, where tapping can be done relatively easily using basic tools, underground systems require specialized equipment and skilled personnel to access and modify the cables.
• Disruption: Excavation work for tapping into underground cables can cause significant disruption to traffic, pedestrians, and the surrounding environment. It may also require obtaining permits from local authorities.
• Risk of Damage: During the process of tapping, there is a risk of damaging the existing underground cables, which can lead to power outages and expensive repairs.

In contrast, tapping for loads and service mains is much easier in overhead systems. The lines are easily accessible, and modifications can be made without the need for excavation or specialized equipment. This accessibility is one of the key advantages of overhead systems over underground systems.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Reduced voltage drops.

This is an advantage of underground systems over overhead systems. Underground cables are typically shorter and have better insulation, which reduces resistance and minimizes voltage drops. Additionally, underground systems are less affected by environmental factors such as temperature and weather conditions, which can impact the resistance and efficiency of overhead lines.

Option 2: Better aesthetics and safety.

Underground systems offer significant advantages in terms of aesthetics and safety. Since the cables are buried, they do not obstruct the visual landscape, making them ideal for urban areas, residential neighborhoods, and locations with strict aesthetic requirements. From a safety perspective, underground systems eliminate the risk of accidental contact with live wires and are less prone to damage from storms, falling trees, or other external factors.

Option 3: Lower chances of power failures.

Underground systems are generally more reliable than overhead systems. They are less susceptible to power failures caused by environmental factors such as high winds, lightning, and snowstorms. Additionally, underground cables are protected from physical damage caused by animals or human activities, further reducing the likelihood of power outages.

Option 4: Tapping for loads and service mains is easier.

As previously explained, this is NOT an advantage of underground systems. Tapping into underground cables is more complex, costly, and disruptive compared to overhead systems.

Conclusion:

While underground power systems offer numerous advantages, such as reduced voltage drops, better aesthetics, enhanced safety, and lower chances of power failures, they are not without their drawbacks. One of the significant disadvantages is the difficulty in tapping for loads and service mains, which is why Option 4 is the correct answer to the question. Understanding the trade-offs between underground and overhead systems is crucial for making informed decisions in power distribution planning and infrastructure development.