A method for producing an electric power transmission cable, comprising the steps of: (a) providing a first armouring wire having two ends and a first tensile strength, said first armouring wire being made of a first metallic material coated with a first metallic protection coating having a thickness more than 100 g/m 2, said first metallic material having a first magnetic permeability μ1, (b) providing a second armouring wire having two ends and a second tensile strength, said second armouring wire being made of a second metallic material coated with a second metallic protection coating having a thickness more than 100 g/m 2, said second metallic material having a second magnetic permeability μ2, and μ2≠ μ1, (c) removing said first metallic protection coating away from one end of said first armouring wire to form a first end with said first metallic material, (d) removing said second metallic protection coating away from one end of said second armouring wire to form a second end with said second metallic material, (e) joining said first end and second end to form a composite armouring wire so that said first armouring wire and said second armouring wire are longitudinally and individually joined to each other by butt welded joint at a joint portion, said joint portion having a third tensile strength, wherein the third tensile strength is at least more than 80% of the first tensile strength and the second tensile strength, (f) painting said joint portion, said first end and said second end with a compound comprising same elements as for said first or second metallic protection coatings (32, 34), (g) cabling a plurality of said composite armouring wires to provide at least a first portion for an electric power transmission cable with plurality of said first armouring wires and at least a second portion for said electric power transmission cable with plurality of said second armouring wires. (a) providing a first armouring wire having two ends and a first tensile strength, said first armouring wire being made of a first metallic material coated with a first metallic protection coating having a thickness more than 100 g/m 2, said first metallic material having a first magnetic permeability μ1, (b) providing a second armouring wire having two ends and a second tensile strength, said second armouring wire being made of a second metallic material coated with a second metallic protection coating having a thickness more than 100 g/m 2, said second metallic material having a second magnetic permeability μ2, and μ2≠ μ1, (c) removing said first metallic protection coating away from one end of said first armouring wire to form a first end with said first metallic material, (d) removing said second metallic protection coating away from one end of said second armouring wire to form a second end with said second metallic material, (e) joining said first end and second end to form a composite armouring wire so that said first armouring wire and said second armouring wire are longitudinally and individually joined to each other by butt welded joint at a joint portion, said joint portion having a third tensile strength, wherein the third tensile strength is at least more than 80% of the first tensile strength and the second tensile strength, (f) painting said joint portion, said first end and said second end with a compound comprising same elements as for said first or second metallic protection coatings (32, 34), (g) cabling a plurality of said composite armouring wires to provide at least a first portion for an electric power transmission cable with plurality of said first armouring wires and at least a second portion for said electric power transmission cable with plurality of said second armouring wires.