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Article 215: Feeders — Episode 4

Feeder Identification, Diagrams & Common Neutral Conductors

Welcome back to Article 215 — Feeders!

How do you identify feeder conductors when a building has multiple voltage systems? Can multiple feeders share a common neutral?

In this episode, we'll cover conductor identification, feeder diagrams, and common neutral conductors.

🏷️ 215.12 — Identification

Feeder conductors must be identified in accordance with the applicable NEC requirements.

Grounded Conductors

Grounded conductors are identified in accordance with 200.7.

Equipment Grounding Conductors

Equipment grounding conductors are identified in accordance with 250.119.

Buildings With a Single Voltage System

Where a building has a single voltage system, the standard conductor identification provisions described in 310.6(A)(3) apply.

Buildings With Multiple Voltage Systems

Where multiple voltage systems are present, each ungrounded feeder conductor must be identified by phase or line and system voltage at each termination point.

Identification may use methods such as:

• Color coding

• Tape

• Tags

The identification scheme must be documented or posted at the originating panelboard, as described in the source material.

DC Systems Over 60 Volts

The source material describes polarity identification requirements for DC systems over 60 volts:

• Conductors 6 AWG and smaller: red for positive and black for negative, or approved lettering.

• Conductors 4 AWG and larger: polarity identification must be documented at terminations.

📐 215.13 — Diagrams

When required by the authority having jurisdiction (AHJ), a feeder diagram must be provided before installation.

The diagram includes information such as:

• The square footage served.

• Total calculated load before and after demand factors.

• The demand factors used.

• Conductor size and type.

Key takeaway

A feeder diagram helps document the design and load calculations for the feeder installation.

🔗 215.14 — Common Neutral Conductors

Article 215 permits certain feeder sets to share a common neutral conductor.

The limits described in this episode are:

Feeder configuration

Maximum sets sharing one common neutral

3-wire feeders

3 sets

4-wire or 5-wire feeders

2 sets

Metal Raceway or Enclosure Requirements

When feeders sharing a common neutral are installed in a metal raceway or enclosure, all feeder conductors sharing that neutral must be grouped together in the same raceway or enclosure.

This helps prevent induction heating concerns.

🧠 Quick Quiz

Question: How many sets of 4-wire feeders can share a single common neutral conductor?

A) One

B) Two

C) Three

D) Unlimited

✅ Correct Answer: B

Under the limits described in 215.14(A), up to two sets of 4-wire or 5-wire feeders may share a common neutral conductor.

For comparison, the source material describes a limit of three sets for 3-wire feeders.

⚡ Episode 4 Takeaway

Proper feeder identification is especially important in buildings with multiple voltage systems. Article 215 also addresses feeder diagrams and limits how many feeder sets can share a common neutral.

Follow for more daily quick-hit study notes!

📚 Next: Episode 5 — Barriers & Surge Protection, the Article 215 Finale.

Study note: This is an educational overview. Consult the applicable 2026 NEC text and local requirements for complete installation rules.

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