A device for carrying out interventions on an electrical transmission or distribution line assembly, comprising a self-propelled lifting machine for lifting a mobile end support relative to a lower base of the machine, at least one robot arm (5, 6), which is provided with tools for remote-controlled execution of a given task on the line assembly and which is attached to the support, characterised in that the robot arm (5, 6) is attached to a platform (7, 8) that is respectively attached to at least two electrically insulating tubes (9, 10) located at a distance from one another and facing each other, a portion (93, 103) of the electrically insulating tubes (9,10) being attached to the end support of the self-propelled lifting machine, the device comprises at least one first robot arm and at least one second robot arm, which are provided with the tools for remote-controlled execution of a given task on the electrical transmission line assembly and which are attached to the support, the first robot arm and the second robot arm are respectively attached to a left platform and to a right platform, which are respectively attached to a left side (91, 101) and a right side (92, 102) of the at least two electrically insulating tubes (9, 10), the left sides (91, 101) of the electrically insulating tubes (9, 10) being located distant from one another and facing each other, the right sides (92, 102) of the electrically insulating tubes (9, 10) being located distant from one another and facing each other, the left side (91, 101) of each electrically insulating tube (9, 10) being connected to its right side (92, 102) by a middle portion (93, 103) of this electrically insulating tube (9, 10) and being distant from its right side (92, 102), the middle portions (93, 103) of the electrically insulating tubes (9, 10) being attached to the end support of the self-propelled lifting machine. the robot arm (5, 6) is attached to a platform (7, 8) that is respectively attached to at least two electrically insulating tubes (9, 10) located at a distance from one another and facing each other, a portion (93, 103) of the electrically insulating tubes (9,10) being attached to the end support of the self-propelled lifting machine, the device comprises at least one first robot arm and at least one second robot arm, which are provided with the tools for remote-controlled execution of a given task on the electrical transmission line assembly and which are attached to the support, the first robot arm and the second robot arm are respectively attached to a left platform and to a right platform, which are respectively attached to a left side (91, 101) and a right side (92, 102) of the at least two electrically insulating tubes (9, 10), the left sides (91, 101) of the electrically insulating tubes (9, 10) being located distant from one another and facing each other, the right sides (92, 102) of the electrically insulating tubes (9, 10) being located distant from one another and facing each other, the left side (91, 101) of each electrically insulating tube (9, 10) being connected to its right side (92, 102) by a middle portion (93, 103) of this electrically insulating tube (9, 10) and being distant from its right side (92, 102), the middle portions (93, 103) of the electrically insulating tubes (9, 10) being attached to the end support of the self-propelled lifting machine.