Good, I have a voltage regulator for a Fiat and I am putting together the electrical installation. I have the scheme to copy it from this page but I am not sure of the thickness of the cables. That is the scheme and the regulator is not the same brand but it has the same letters and also the numbers (15 - 30 - 68 - 86) I do not remember the last 2 but the letters are the same. Anyway, my question is whether the cable that goes to 15 (IGN in the scheme) of the regulator that passes through the contact and the lamp is the one that passes the amperage that loads the alternator or is simply to excite the regulator and a lamp Witness I'm using a 0.5mm2 cable for that, should I use a thicker one? Regards..

you should use at least 2.5 mm at least.