Though mostly immune to wind-related damage, undergrounding facilities are prone
to flooding. Undergrounding also presents significant challenges, namely longer
repair time and much higher repair costs; damage to underground facilities from
Sandy reinforced that. Investor-owned utilities in North Carolina compared five
years of underground and overhead reliability data and found the frequency of
outages on underground systems was 50% less than for overhead systems, but the
average duration of an underground outage was 58% longer.
