The present invention relates to a method as well as to a joint assembly (12) for splicing a first and a second electric cable (1, 2) by means of a tubular elastic sleeve (15) at a splicing zone (11) between such cables (1, 2), said tubular sleeve (15) being supported in an expanded condition on a removable hollow supporting element (16) detachable in a first supporting portion (17) and a second supporting portion (18). The method of the invention comprises the steps of - providing a tubular elastic sIbeve (15) supported ina radially expanded condition on a removable hollow supporting element (16) detachable in a first supporting portion (17) and a second supporting portion (18), - placing the sleev e (15) fitted on the supporting element (16) substantially coaxially with one of the first electric cable (1) and of the second electric cable (2) and radially external thereto, - forming an electric connection between the conductors (3, 4) thereby obtaining a splicing zone (11), - placing the sleeve (15) fitted on the supporting element (16) substantially coaxially with said the zone (11) and radially external thereto, - triggering an axial displacement of the first and second supporting portions (17, 18) so as to start an elastic recovering of the tubular sleeve (15) onto the splicing zone (11) capable to expel the first and second supporting portions (17, 18) from the sleeve (15) at an expulsion speed, and - adjusting the expulsion speed of the first and second supporting portions (17, 18) away from the splicing zone (11) so as to adapt the expulsion speed to the elastic recovering of the tubular sleeve (15).