Voltage Drop Calculator
Calculate voltage drop in electrical circuits and ensure NEC code compliance
Circuit Parameters
Enter your electrical circuit specifications
NEC Code Requirements
Voltage Drop Limits (NEC 210.19(A)):
- Branch circuits: 3% maximum
- Feeders: 3% maximum
- Combined (feeder + branch): 5% maximum
- Sensitive equipment: 2% recommended
Wire Ampacity (NEC 310.15):
- Based on conductor material and insulation
- Temperature derating may be required
- Bundling adjustments apply
Calculation Tips
Important: Always verify calculations with local electrical codes and consult with a qualified electrician for actual installations.
Key Considerations:
- Distance is one-way length of conductor
- Temperature affects wire resistance
- Power factor important for AC calculations
- Consider future load growth
- Check both ampacity and voltage drop
Common Applications
Residential:
- • Branch circuits
- • Service feeders
- • Subpanel feeds
- • Appliance circuits
Commercial:
- • Distribution panels
- • Motor circuits
- • Lighting systems
- • HVAC equipment
Industrial:
- • High-current feeders
- • Long-distance runs
- • Critical equipment
- • DC systems