Introduction
Commercial electrical systems are only as reliable as the backbone that powers them — services and feeders. The National Electrical Code (NEC) dedicates entire articles to these components because improper design, installation, or labeling can lead to inspection failures, downtime, and safety hazards.
For contractors, knowing NEC requirements for services and feeders is critical not only for compliance but also for keeping projects efficient and profitable. In this guide, we’ll break down NEC Articles 230 (Services) and 215 (Feeders), highlight common mistakes, and explain how proper labeling helps you pass inspections the first time.
For a full overview of the NEC, start with our NEC Code Explained: What It Is and Why It Matters guide.
What Are Services and Feeders?
Before diving into code, let’s clarify:
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Service – The point where electrical power from the utility enters the building, including the service conductors, service equipment, and the main disconnecting means.
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Feeders – The conductors between the service equipment and branch circuit panels, distributing power throughout the facility.
Think of services as the gateway and feeders as the highways distributing power inside.
NEC Article 230 – Services
1. Service Conductors
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Must have ampacity sized per load calculations (see Article 220).
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Require clearances above roofs, sidewalks, and driveways (typically 10–12 feet minimum).
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Must be protected against physical damage.
2. Service Disconnecting Means
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Every building must have a readily accessible main disconnect (NEC 230.70).
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Disconnects must be grouped and clearly marked.
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Maximum of six disconnects are permitted (the “Rule of Six”), though many jurisdictions enforce a single main.
3. Overcurrent Protection
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Service equipment must provide proper short-circuit and overload protection.
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Conductors must be protected per their ampacity.
4. Grounding & Bonding
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NEC requires grounding electrode systems at the service.
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Proper bonding ensures metal parts are at the same potential, reducing shock hazards.
NEC Article 215 – Feeders
1. Conductor Sizing
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Feeder conductors must be sized for the calculated load demand (NEC 215.2).
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Conductors must be protected against voltage drop — generally no more than 3% per feeder, with a combined 5% drop allowed for feeder + branch circuit.
2. Overcurrent Protection
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Feeders require OCPD (Overcurrent Protection Devices) sized to protect the conductors (NEC 215.3).
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OCPDs must be located at the supply end of the feeder.
3. Feeder Taps
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Tap conductors must follow specific rules (NEC 240.21), often a pain point during inspections.
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Misapplied feeder taps are one of the top NEC violations in commercial work.
4. Grounding
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Feeders must include an equipment grounding conductor or otherwise provide effective fault current path (NEC 215.6).
Common Contractor Mistakes with Services and Feeders
Contractors frequently run into:
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Undersized feeders → overheating, failed inspections.
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Confusion with multiple service disconnects → misapplied “six-handle rule.”
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Improper feeder taps → inspectors red-tagging installations.
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Voltage drop ignored → lights dimming, motors stalling.
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Lack of proper labeling → inspectors failing jobs due to non-compliance with NEC 110.22.
Why Proper Labeling is Non-Negotiable
NEC requires all service equipment, feeders, and disconnects to be clearly marked for identification. (See NEC 110.22 and 230.2(E)).
Without proper labels:
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Inspectors can fail your project.
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Maintenance crews face safety risks.
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Emergency responders may not find the correct disconnect.
At Print Pro, we supply NEC-compliant labels for:
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Service disconnects
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Feeder panels and subpanels
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Voltage and arc flash warnings
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Circuit directories
This ensures you’re compliant, safe, and ready for inspection day.
Pro Tips for Contractors
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Always perform accurate load calculations before sizing services/feeders.
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Use copper when possible for feeders to reduce voltage drop and improve longevity.
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If running long feeders, consider step-up/step-down transformers to minimize loss.
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Pre-label panels and disconnects during rough-in — inspectors love seeing foresight.
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Keep NEC Article 230 and 215 bookmarked — these are common inspection points.
Conclusion
Services and feeders are the backbone of commercial electrical systems. By following NEC Articles 230 and 215, performing accurate calculations, and using proper NEC-compliant labels, contractors can avoid costly inspection delays, keep projects safe, and ensure long-term reliability.
For a broader look at NEC, read our NEC Overview Guide.
👉 Ready to get inspection-ready labels for your next project? Visit PrintProAZ.com to order NEC-compliant service and feeder labels today.
