Not terribly old as a whole but old for a 13.8kv grounded why single phase. This makes me wonder more about the history of SC&G in Charleston SC area being most 23.9/13.8kv lines are generally newer in general but this obviously being an old single phase in service.

It very rare to find SC&G poles with old equipment being this utility invests heavily on replacing just about every pole with the last few years.