Voltage drop wrapper
Why you care (60 seconds)
Excessive voltage drop causes equipment issues and customer complaints. While often treated as a design target, it affects real-world performance.
Where people lose time
- Assuming voltage drop is not worth checking on long runs.
- Using incorrect conductor lengths or load current values.
- Ignoring voltage drop when upsizing conductors for other reasons.
This is
The rule in plain language
Plan conductor sizes so voltage drop stays within recommended limits for good performance, especially on long runs.
When it applies
Long branch circuits and feeders where conductor length and load could create noticeable voltage drop.
What you must do (checklist)
- Calculate voltage drop using actual run length and load current.
- Adjust conductor size if voltage drop is too high.
- Document assumptions for length and load.
Quick examples
- A long feeder may need a larger conductor to keep voltage drop reasonable.
- High starting currents can worsen voltage drop in motor circuits.
This is not
Common misreads
- Treating voltage drop as a code violation in every case.
- Ignoring voltage drop for sensitive equipment.
What it doesn't cover
- Power quality studies or harmonic analysis.
- Utility service voltage regulation.
False friends
- A conductor sized for ampacity may still have excessive voltage drop.
Exceptions & edge cases
- Critical loads may need stricter voltage drop limits.
- Parallel conductors can change voltage drop calculations.
Cross-references (NEC map)
- Primary: 210.19(A)(1), 215.2(A)(1)
Exam traps
- Using incorrect run length (one-way vs round-trip).
- Mixing up voltage drop and ampacity requirements.
Field notes
- Keep a voltage drop calculator in your field toolkit.
- Note voltage drop assumptions in submittals.
AHJ / Local amendments notes (placeholder)
- Add local amendments or interpretations here.
Revision notes
- Draft wrapper created for voltage drop fundamentals.