About Wire Size Calculations

You can automatically calculate wire sizes for circuited wire runs. As you add wire, you can use the instant sizing tool to automatically calculate wire sizes based on the circuit rating. You can also use the Circuit Manager to calculate wire sizes for any wires assigned to a circuit. Wire sizes are calculated based on the National Electrical Code (NEC) 2002 Handbook: Table 250.122 for ground conductors, and Table 310.16 for current-carrying conductors.