This article presents a case study of the failures due to a serious design mistake of several transmission cables rated 110 kV and above in three utilities (A, B, and C) located in different countries. Utility A encountered the problem in the 1990s and solved it by modifying the cable design. However, the cable contractor to utility B was not aware of the problem encountered by utility A and its successful solution, and three 230-kV crosslinked polyethylene (XLPE) cables operated by utility B failed in the early 2000s. Recently, a few 220-kV cables operated by utility C were found to have the same problem, but again the relevant cable contractor was not aware of the design error and the solution. Clearly, there is an urgent need for utilities to share their operation and maintenance experiences as part of smart CM.