## drop voltage

I got some trouble in drop voltage (VD) calculation of revit 2014.
In a simple case (same panel and same light), the VD is strongly influenced by wire setting and electrical setting (and electrical starting country template).

In my personal case, the italian electrical template and wire defualt setting doesnt give me a right VD calculation. Our cable size (ampere, dimension, diameter) are proportional to the current that across the cable.

By a standard italian electrical default template, If I can substitute the wire name (=dimension=14,12,10,8,6,4,3,2,1,1/0,2/0,ecc) with the desiderate/personalized one (es. 1mmq, 1.5mmq, 2.5mmq, ecc), the diameter will be editable (by normal tool), and the drop voltage, will be calculate rightly.

(respecting NEC/AWG) Can you help me in finding "where" I can edit the wire name = dimension in the revit source code and obtain a (right) VD? Actually.
es. 2 light 500W each (tot 1000W) / 230V = 4.34 A
result: wire 2#12, VD 0.46V
If I change #12 with 2.5mm the VD = zero.

waiting your response, I thank you.