Most live works carried out on distribution overhead lines require the displacement and support of conductors by means of: the assembly of hot sticks, or the jib of an aerial lift with insulating boom, or suspension pullers, or tension pullers. In order to ensure safe operations, it is essential to be able to assess the conductor stress and the loads on the tools and to verify that they do not exceed prescribed limits. Therefore, for more than 25 years SERECT has developed ECART, a calculation program now released as a JAVA application for Windows and available in several languages. This paper intends to recall the basics of overhead line mechanics embedded by ECART and to present the software features.