NEC 2023 Voltage Drop Changes: What You Need to Know
A comprehensive look at how NEC 2023 addresses voltage drop requirements, including new informational notes and practical implications for electrical designers.
The NEC 2023 edition brings important clarifications to voltage drop recommendations that every electrical professional should understand. While voltage drop remains an informational note rather than a mandatory requirement, the updated language provides clearer guidance for designers and installers.
Key Changes in NEC 2023
The 2023 NEC maintains the fundamental voltage drop recommendations from previous editions but includes refined language that emphasizes the importance of voltage drop analysis for efficient electrical system operation. The core recommendations remain unchanged: 3% maximum for branch circuits, 3% for feeders, and 5% total from service entrance to the farthest outlet.
What's significant about the 2023 edition is the continued emphasis that these recommendations, while informational, represent engineering best practice. The code clearly states that conductors sized to meet these voltage drop limits "provide reasonable efficiency of operation"—language that AHJs and specifying engineers increasingly treat as a de facto requirement.
Section 210.19(A) Informational Note No. 4
"Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, provide reasonable efficiency of operation."
This informational note remains substantively unchanged from NEC 2020, confirming that the electrical industry has reached consensus on appropriate voltage drop limits for typical installations. The stability of this guidance allows designers to confidently apply these recommendations knowing they represent current best practice.
Practical Implications for Designers
While the NEC voltage drop requirements haven't changed dramatically, the industry context has evolved significantly. Consider these factors when applying NEC 2023:
- EV Charging Growth: The explosion of EV charger installations creates many long-run branch circuits where voltage drop is the controlling design factor. NEC 2023 Article 625 addresses EV charging but relies on the general voltage drop recommendations.
- Energy Efficiency Focus: With increasing emphasis on building energy performance, specifiers are more frequently requiring voltage drop analysis as part of design documentation.
- Sensitive Electronics: Modern buildings contain more electronic loads sensitive to voltage quality. The general 3%/5% limits may be insufficient for some applications.
Best Practices for NEC 2023 Compliance
Do
- • Calculate voltage drop for all circuits over 50 feet
- • Document calculations in design files
- • Consider 2% branch / 3% feeder for sensitive loads
- • Verify with field measurements post-installation
Avoid
- • Ignoring voltage drop because it's "just informational"
- • Using voltage drop as the only sizing criterion
- • Assuming 5% is acceptable for all applications
- • Forgetting to account for motor starting currents
Calculate to NEC 2023 Standards
Use our professional voltage drop calculator to verify your designs meet NEC 2023 recommendations. The calculator automatically checks your results against the 3% and 5% limits and provides clear compliance indication.
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