#### 32Lateralus

##### Member

- Location
- West Coast

- Occupation
- Electrical

The first method Ive seen used by many places around town is Isc=V/Z. In this case you calculate the total impedance starting from NEC 'table 9' and then divide the voltage by total calculated impedance. However I cant seem to find where this full calculation is written out or described as the acceptable method.

The second method is the point-to-point method used by Eaton/Bussman calc:

Is one of these a more accurate/correct method? Have you seen AHJ's every require one over the other?