Voltage Drop NEC Tables 8&9

NEC voltage drop calculator for electricians, apprentices, and electrical engineers. Calculate voltage drop instantly using official NEC Chapter 9 data Tables 8 and 9. This electrical feeder sizing calculator supports single-phase and three-phase circuits with copper or aluminum conductors. Works 100% offline on the job site. Whether you're running a long feeder to a sub-panel or checking branch circuit voltage drop for a commercial project, this voltage drop calculator gives you accurate NEC-compliant results in seconds. Enter your wire length and circuit distance to check voltage loss - use it as your feeder sizing tool for any run length from short circuits to long-distance feeders. VOLTAGE DROP CALCULATOR FEATURES: • Single-phase and three-phase voltage drop calculations • 5 voltage presets: 120V, 208V, 240V, 277V, 480V • Copper and aluminum conductors: 14 AWG through 1000 kcmil • 3 conduit types: PVC, Aluminum, Steel — separate AC resistance and reactance per conduit • NEC Chapter 9 Table 9 effective impedance (Z) at power factor • Custom power factor support (default 0.85) • Voltage drop in volts and percentage • PASS/FAIL indicator based on NEC 3% recommendation • Recommends minimum wire size to meet 3% voltage drop threshold • Shows voltage at load end NEC VOLTAGE DROP REFERENCES: • NEC 210.19(A) Info Note 4 - Branch circuit: max 3% voltage drop • NEC 215.2(A) Info Note 2 - Feeder: max 3% voltage drop • Combined feeder + branch: max 5% voltage drop • Chapter 9 Table 8 - DC resistance at 75°C • Chapter 9 Table 9 - AC resistance, reactance, effective Z PRO FEATURES (one-time purchase): • No ads - clean interface for professionals • Save voltage drop calculation history • Export calculations as PDF reports for permits and records • Dark theme support BUILT FOR ELECTRICIANS ON THE JOB SITE: This voltage drop calculator is designed by electricians, for electricians. Enter your circuit parameters, see voltage drop instantly, and get a recommended wire size - no complicated menus or unnecessary features. ACCURATE NEC VOLTAGE DROP DATA: All resistance and reactance values are sourced from NEC Chapter 9. Effective impedance is calculated using Z = R·cos(θ) + XL·sin(θ) per the NEC method. Always verify voltage drop calculations against the official NEC code book before installation. PERFECT FOR: • Licensed electricians checking voltage drop daily • Electrical apprentices studying for journeyman exams • Electrical engineers and designers • Electrical contractors bidding commercial and residential jobs • Long feeder runs and sub-panel installations • NEC code exam preparation OFFLINE & PRIVACY: • Works 100% offline - no internet needed on the job site • No account required • No data collection - your voltage drop calculations stay on your device Simplify your voltage drop calculations on the job site.