Underground lines can be more reliable than overhead lines due to their resilience to being compromised by trees, winds, and other inclement weather. EPUD has moved some of the more problematic areas of our District to underground lines in order to bring the best service possible to our Customer-Owners. Moving all lines underground, however, is cost-prohibitive and is often not the correct action to take for other reasons as well. Following is a rough estimate of the difference in costs between building overhead and underground line, based on the capacity of the line:
6 megawatt (MW) line:
- Build new overhead: $28 per foot
- Build new underground or convert overhead to underground: $50 per foot
14 MW line:
- Build new overhead: $30 per foot
- Build new underground line: $125 per foot plus
In addition to these costs, there are add-in costs associated with flagging, special circumstances, etc., as it takes longer to build underground than overhead, which accentuates the difference in costs between overhead and underground.
It should also be noted that underground lines are not the perfect solution in all instances. It is problematic to read automated meters that are downstream of underground systems, and more importantly, underground lines severely limit our flexibility in operating and expanding the system.
EPUD makes the decision to install underground or overhead line based on what we feel is best for our Customer-Owners now and into the future.