Applications 15 min
Wire Sizing Methods
Methods for Selecting Wire Size
Wire sizing must consider both ampacity (current-carrying capacity) and voltage drop. The larger of the two requirements determines the final wire size.
Step 1: Determine Ampacity Requirement
Use NEC Table 310.16 to find minimum wire size for the load current.
Step 2: Calculate Voltage Drop
Verify the selected wire meets voltage drop requirements (<3% branch, <5% total).
Start Calculating
Ready to apply these concepts to your project? Use our professional voltage drop calculator.
Open Calculator