EHV efficiency versus real-world constraints: the pros and cons of "right-sizing" the grid. The Hidden Cost of "In-Kind" Replacement In the world of transmission planning, the path of least resistance is often the one already traveled. When an aging 138 kV or 230 kV line reaches the end of its useful life, the default regulatory and operational impulse is often "in-kind" replacement—swapping old towers for new ones of the same voltage. The scope is a straightforward rebuild;