This video was captured in 2002 at a BPA substation located at the Haskill tap of the Libby-Conkelley No.1 230 kV transmission line near ... all » Kalispell Montana. It shows a three phase vertical break disconnect switch attempting to de-energize an unloaded 34 mile long section of transmission line. This switch was part of an experimental design and is no longer in service. Air break disconnect switches are not intended to actively switch load current. In the clip, the arcing is due to the attempted interruption of comparatively low reactive (capacitive or "charging") currents drawn by the open transmission line. Even with the reduced current, the disconnect switch was not always capable of opening the circuit. At the very end of the clip, a brief phase-to-phase power arc causes the upstream line interrupters to open, finally extinguishing the arcs.