Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning rising mains in a tall building and how to size them, is answered by SELECT:
Question: I have a query regarding rising mains. I'm working on a tower block of 61 floors and I am using rising mains to serve the floors. I have chosen 10 floors for each set of rising main. My total load on each rising main at the breaker incoming point is 1000A. As I move towards the loads, the load on the rising mains decreases. I am using copper busbars. It is possible to use rising mains in sections such as 1000A, 800A and then 630A. Is it wise to reduce the sections of busbars? And if this is not possible, is it because of short circuit ratings?
Similarly, if the LV panel concerned has very long bus bars, will the above have some impact on busbar sizing of the panels? For example, why have the same size of busbar throughout the panel when load decreases as we move away from the incomer?
Answer: With projects obviously as large as the one you described, I would strongly recommend that you seek advice from a busbar manufacturer before completing your design.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
https://www.voltimum.co.uk/consult.php?universe=consult.index.questions