A method of installing an optical aerial line, comprising arranging an optical cable parallel to an aerial electrical conductor (3, 4) and lashing the optical cable to the aerial electrical conductor (3, 4), wherein: a) arranging an optical cable parallel to an aerial electrical conductor (3, 4) comprises arranging an optical cable underneath the aerial electrical conductor (3, 4), b) lashing the optical cable to the aerial electrical conductor (3, 4) comprises helically winding at least two non adhesive binders (8a, 8b, 8c, 8d) around the aerial electrical conductor (3, 4) and the optical cable with a binder winding pitch and locking the optical cable and the binders with hardware accessories at both ends of a span, c) the tension of application of said binders (8a, 8b, 8c, 8d) is comprised between 9.8 and 98N (1 and 10 kg), d) the binder winding pitch is of at most 200 mm, and e) starting from predetermined diameter values of electrical conductor (3, 4) and of optical cable, the number, N, of said binders (8a, 8b, 8c, 8d), the tension, T, of application of said binders (8a, 8b, 8c, 8d) and the binder winding pitch, P, are selected so as to have a binding force, F, for unit length of the electrical conductor of at least 49 N/m (5 kg/m); f) the binding force, F, is expressed according to the following equation: F = N ⋅ 2 T / P ⋅ sinα ⋅ cosβ where: β = Arc sin | r 2 − r 1 | / r 1 + r 2 where r 1 is the radius of the optical cable and r 2 is the radius of the electrical conductor; and α = Arc tan C / P where: for r 1 ≥r 2 C = r 1 ·(π·(180+2β/180) + r 2 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ for r 2 ≥r 1 C = r 2 ·(π·(180+2β/180) + r 1 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ. a) arranging an optical cable parallel to an aerial electrical conductor (3, 4) comprises arranging an optical cable underneath the aerial electrical conductor (3, 4), b) lashing the optical cable to the aerial electrical conductor (3, 4) comprises helically winding at least two non adhesive binders (8a, 8b, 8c, 8d) around the aerial electrical conductor (3, 4) and the optical cable with a binder winding pitch and locking the optical cable and the binders with hardware accessories at both ends of a span, c) the tension of application of said binders (8a, 8b, 8c, 8d) is comprised between 9.8 and 98N (1 and 10 kg), d) the binder winding pitch is of at most 200 mm, and e) starting from predetermined diameter values of electrical conductor (3, 4) and of optical cable, the number, N, of said binders (8a, 8b, 8c, 8d), the tension, T, of application of said binders (8a, 8b, 8c, 8d) and the binder winding pitch, P, are selected so as to have a binding force, F, for unit length of the electrical conductor of at least 49 N/m (5 kg/m); f) the binding force, F, is expressed according to the following equation: F = N ⋅ 2 T / P ⋅ sinα ⋅ cosβ where: β = Arc sin | r 2 − r 1 | / r 1 + r 2 where r 1 is the radius of the optical cable and r 2 is the radius of the electrical conductor; and α = Arc tan C / P where: for r 1 ≥r 2 C = r 1 ·(π·(180+2β/180) + r 2 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ for r 2 ≥r 1 C = r 2 ·(π·(180+2β/180) + r 1 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ. for r 1 ≥r 2 C = r 1 ·(π·(180+2β/180) + r 2 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ for r 2 ≥r 1 C = r 2 ·(π·(180+2β/180) + r 1 ·(π·(180-2β/180) + 2·(r 1 +r 2)·cosβ.