Hello Raffaele;
You have posted this thread in the Nonferrous section so the first question is " Are you referring to bare wire only?"
If your answer is "Yes" to the above question you could be referring to 7 or 19 wire strands in a single or double twist strander, closing layers of self damping ACSR or closing a 1600 square millimeter Milliken conductor. In other words, the information you provide is the most important thing.
Please clarify your question including the metal and design you are referring to. Thank you.
Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641-3212