The ice coats are built on 25 kV overhead contact wire when the temperature is lower than $0^{circ}C$. It generates shockwaves at the mechanical interface of the collecting strips of the pantograph and the contact wire. The de-icing processes should be performed to avoid shockwaves which are generated by a pulsed high-voltage arc discharge. This paper presents temperature analysis of the de-icing effects which could be applied to the overhead contact wire of railways using Joule heat. The results show that 350 A is the proper current for $0^{circ}C$ conductor according to environmental condition such as velocity of air stream, ambient temperature and moisture.