NEC Chapter 9 Table 8 Compliant
Single-Phase Voltage Drop Calculator
Determine voltage drop ($V_d$), percentage loss ($\%V_d$), and recommended AWG conductor size for 120V/240V single-phase systems.
Direct Calculation Formula & NEC Guidelines
Single-Phase Circular Mil ($CM$) required: CM = (2 × K × I × D) / V_d
Where K = 12.9 Ω·cmil/ft for Copper, 21.2 Ω·cmil/ft for Aluminum (at 75°C), I = Load Current (Amps), D = One-Way Distance (Feet), and V_d = Allowable Voltage Drop (Volts). Standard NEC 210.19(A) recommends max 3% voltage drop for branch circuits.
Circuit Parameters
20 A
Voltage Drop ($V_d$)
4.75 V
Drop Percentage
3.96%
NEC Status (≤3%)
NON-COMPLIANT
Voltage Drop Scale Meter
3.96% of Source Voltage
0%
3% NEC Limit
10% Max
Recommended Minimum Wire Size for ≤3% Limit
Calculated Minimum Circular Mils
8,600 CM
Safe AWG Recommendation
10 AWG
Submit Electrical Sizing Calculation Report
Route calculation results directly to engineering support for formal review.