Calculate voltage drop for branch circuits and feeders. Includes reverse solve to find the minimum wire size for your target drop percentage.
Based on NEC 2023 Chapter 9 Table 8, 210.19(A) Informational Note
This calculator provides estimates for reference purposes only. Results must be verified by a licensed electrician or electrical engineer before any installation.
NEC Reference: NEC 2023 Chapter 9 Table 8, 210.19(A)
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Voltage drop is the reduction in voltage as current flows through a conductor. Excessive drop causes equipment malfunction and wasted energy.
VD = (2×K×L×I) ÷ CMVD = (1.732×K×L×I) ÷ CM12.9
21.2
⚠️ IMPORTANT LEGAL DISCLAIMER
For Reference Only: This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional engineering design, advice, or certification.
Code Compliance: Calculations are based on the 2023 National Electrical Code (NEC®). However, local codes, amendments, and Authority Having Jurisdiction (AHJ) requirements vary by location and may supersede standard NEC requirements.
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