On 11 Sep, 11:11, Boltar wrote:
On Sep 11, 10:40 am, wrote:

It is an unpowered overrun wire, to guard against a train running with
a raised pantograph. It was installed at the time of the BR takeover
of the line.

How far does it run? I don't remember seeing it at Moorgate.

B2003

I'll guess not far - as aren't the traction systems interlocked so
that when a driver changes to third-rail at Draytom Park the
pantograph gets lowered. In which case the unpowered overrun line just
needs to exist for as far as the train could coast for until it ground
to a powerless halt!

I don't think any driver doing this would make themselves at all
popular, given the 10 minute service frequency that operates to and
from Moorgate in the Great Northern tunnels!