Delagation writes letter to WMATA "demanding’ complete listing of power cable connector insulators that are missing system wide. Evidently NTSB found this a cause of the tunnel fire.
http://www.scribd.com/doc/268178642/NCR-Reg-Del-Letter-to-Metro-Re-NTSB-Wiring-Recs-FINAL-06-09-15
Now a question would be is how many third rail systems do not have these insulators ?