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A '''third rail''' is the [[railway track|rail]] of a three-rail [[electric railway]] line separate to the two rails (the running rails) which carry trains, that carries the current to power the trains.

A '''third rail''' is the [[railway track|rail]] of a three-rail [[electric railway]] line separated to the two rails (the running rails) which carry trains, that carries the current to power the trains.

[[electricity|Electric]] trains on such a system have a "shoe" that contacts the third rail to collect the current, which is returned in one of the two running rails.

[[electricity|Electric]] trains on such a system have a "shoe" that contacts the third rail to collect the current, which is returned in one of the two running rails.

Some [[railway]]s have a fourth rail for the return of the current.

Some [[railway]]s have a fourth rail for the return of the current.

Voltage in the third rails is typically 600 volts DC, so touching it while earthed usually proves fatal.

[[Voltage]] in the third rails is typically 600 volts DC, so touching it while earthed usually proves fatal.

The "'''third rail'''" of politics is an issue so potent and one-sided that no politician dares challenge the traditional view.

The "'''third rail'''" of politics is an issue so potent and one-sided that no politician dares challenge the traditional view.