The self-supporting system consists of 4 insulated aluminium alloy conductors. The 4 insulated conductors hold the same mechanical strength and cross section. When straining the line, all 4 conductors are allocated to share the pulling force identically. Additional 1 or 2 insulated aluminium conductors with cross sections of 16 mm2 or 25mm2 may be applied as pilot wire or for street lighting.