Voltage Drop Calc NEC

NEC voltage drop calculator for electricians, apprentices, and electrical engineers.

Calculate voltage drop instantly using official NEC 2023 Chapter 9 data (Tables 8 and 9). Supports single-phase and three-phase circuits with copper or aluminum conductors. No internet required - works 100% offline on the job site.

FEATURES:
- Single-phase and three-phase 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% threshold
- Shows voltage at load end

NEC REFERENCES:
- NEC 210.19(A) Info Note 4 - Branch circuit: max 3%
- NEC 215.2(A) Info Note 2 - Feeder: max 3%
- Combined feeder + branch: max 5%
- 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
- Save calculation history
- Export calculations as PDF reports
- Dark theme support

BUILT FOR THE JOB SITE:
This app 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 DATA:
All resistance and reactance values are sourced from NEC 2023 Edition, Chapter 9. Effective impedance is calculated using Z = R·cos(θ) + XL·sin(θ) per the NEC method. Always verify calculations against the official NEC code book before installation.

PERFECT FOR:
- Licensed electricians
- Electrical apprentices
- Electrical engineers and designers
- Electrical contractors
- DIY electrical projects
- NEC code exam preparation

OFFLINE & PRIVACY:
- Works 100% offline - no internet needed
- No account required
- No data collection
- Your calculations stay on your device

Simplify your voltage drop calculations on the job site.