Voltage Drop, Lighting Calculation (Zonal Cavity Method) Software available

How are you calculating voltage drop? Your calculator does not give the same voltage drop as the K method.

Example the following is pretty much standard for electricians in the USA: VD = 2 x K x L x I /CMA (multiply by .866 for three phase three wire and by .5 for three phase four wire) K = 12.9 ohms per circular mil foot for copper and 21.2 for aluminum (required by State of Washington) L = equals one way circuit length in feet I = current in amperes CMA = circular mil area of conductor from Chapt 9 Table 8 of the NEC