WASHINGTON — Metro’s Red Line trains had to single-track between Medical Center and Friendship Heights for about a half-hour at the height of Wednesday’s morning rush due to an arcing insulator.

Metro began single-tracking just before 8:30 a.m.

D.C. Fire and EMS supervisors on the scene said the problem was limited to smoke from the insulator that runs along the third rail.

The incident caused delays for passengers, although both stations remained open.

No injuries were reported.

Regular two-track service resumed just before 9 a.m.

A few days earlier, on Saturday, a similar insulator fire occurred nearby, in the stretch of track between Friendship Heights and Tenleytown.

At least nine people were evacuated from a train at Tenleytown after smoke filled the tunnel. No injuries were reported.

In January 2015, a woman died aboard a smoke-filled train after a similar situation caused heavy smoke at the L’Enfant Plaza station.

Last year, Metro said approximately two arcing incidents per month  on Metro are blamed on failed insulators.