Which of the following is NOT listed as an advantage of rising main busbar systems in multi-storey buildings?

• A. Takes up more space overall
• B. Greater mechanical strength over long runs
• C. Lower voltage drop in most cases
• D. Provide better resistance to the spread of fire

Answer: (A)

Rising main busbar systems centralize the power distribution along vertical risers, which provides several clear benefits. The rigid metal bars give greater mechanical strength over long runs, helping withstand physical stresses and vibrations in a tall building. The shorter, more direct path from source to load reduces impedance, so voltage drop is typically lower in most cases. They are also designed to run within fire-rated enclosures and barriers, which can help slow the spread of fire compared with long runs of individual cables, enhancing fire resistance. Additionally, using a single vertical busbar system often saves space and reduces the amount of conduit and wiring needed compared with many separate cables in each floor.

Therefore, the statement that they take up more space overall is not an advantage; rising main busbar systems actually tend to be more space-efficient.