Difference between revisions of "Third rail"
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| − | A '''third rail''' is the [[railway track|rail]] of a three-rail [[ | + | 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. |
Electric trains on such a system have a "shoe" that contacts the third rail to collect the current, which is returned in the two running rails. | Electric trains on such a system have a "shoe" that contacts the third rail to collect the current, which is returned in 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. | ||
Revision as of 02:49, June 4, 2007
A third rail is the 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. Electric trains on such a system have a "shoe" that contacts the third rail to collect the current, which is returned in the two running rails. Some railways 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.
The "third rail" of politics is an issue so potent and one-sided that no politician dares challenge the traditional view. Social Security and other benefits for senior citizens, who vote in greater proportion to other age groups, represent the classic third rail of politics. The term derives from the railway use.