A third rail heating system is essential to keep a third rail free of ice and snow for uninterrupted service of a 3rd rail traction power rail vehicle.
The electric rail car typically connects to the third rail via a shoe on the rail car that touches and rides on top of the third rail. There are typically at least two shoes per car per side of the car.
The wattage of this type of heater does not need to be as large as a switch point heater because the shoes will brush off loose ice/snow. The ice/snow is loosened by a lower wattage thus allowing the shoe to brush off the ice/snow by forming a thin film of water just above the rail. Typically the entire 3rd rail needs to be heated to keep the rail clear.