Usually,a high voltage is carried by the overhead-wire system,and the third rail has current at a much lower voltage. This is because of the danger that a man on the line might touch the electric rail,but he can not touch an overhead wire.
英
美
- 通常，高壓電被高架線(xiàn)系統輸送，第三根鐵軌里的電壓則是很低的，這是因為如果一個(gè)站在線(xiàn)路上的人就可能碰到電軌，那是很危險的，但是他不可能碰到高架線(xiàn)。
