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⚡ JoshTheSparky — 2026 NEC Quick Hits

Article 215: Feeders — Episode 3

Ground-Fault Protection of Equipment & Autotransformer Feeders

Welcome back to Article 215 — Feeders!

This episode covers two important topics: ground-fault protection of equipment (GFPE) and feeders supplied through autotransformers.

First, let's separate GFPE from GFCI protection.

⚡ 215.10 — Ground-Fault Protection of Equipment

GFPE is intended to protect equipment against damaging ground faults.

It is different from GFCI protection, which is commonly associated with protection against electric shock.

(A) Solidly Grounded Wye Systems

For the systems described in 215.10(A), feeder disconnects rated 1000 amperes or more on solidly grounded wye systems operating over 150 volts to ground, up to 1000 volts phase-to-phase, require GFPE in accordance with 230.95.

(B) Solidly Grounded DC Systems

The provision also addresses solidly grounded DC systems.

The general trigger described in the source material is a feeder disconnect rated 1000 amperes or more, on systems over 150 volts to ground and up to 1500 volts line-to-line.

Exceptions

The source material identifies exceptions involving:

• Continuous industrial processes where an unplanned shutdown creates a greater hazard.

• Situations where GFPE is already provided upstream and downstream of a transformer supplying the feeder.

• Temporary generator-connection feeders used for repair, maintenance, or emergency purposes, for a maximum of 90 days.

Always check the applicable provision for the exact conditions and limitations of an exception.

🔄 215.11 — Autotransformer Feeders

A feeder generally cannot be derived from an autotransformer unless the grounded conductor of the supplied system is electrically connected back to the grounded conductor of the source system.

This follows the same general concept covered for branch circuits in 210.9.

Exceptions Described in This Episode

Exception 1: 208-to-240-volt transformations do not require the grounded-conductor connection described in the general rule.

Exception 2: Certain industrial installations limited to qualified persons may use 480-to-600-volt autotransformer feeders without that connection.

The applicable conditions must be verified before relying on either exception.

🧠 Quick Quiz

Question: Under 215.10(A), GFPE is generally required on feeder disconnects rated at what minimum amperage?

A) 200 amperes

B) 400 amperes

C) 800 amperes

D) 1000 amperes

✅ Correct Answer: D

The general threshold described in 215.10(A) is 1000 amperes or more for the specified solidly grounded wye systems operating over 150 volts to ground.

Remember that the system characteristics and applicable exceptions also matter.

⚡ Episode 3 Takeaway

GFPE and GFCI serve different purposes. Article 215 also places specific conditions on feeders derived from autotransformers, including exceptions for certain voltage transformations and industrial applications.

Follow for more daily quick-hit study notes!

📚 Next: Episode 4 — Feeder Identification, Diagrams & Common Neutral Conductors.

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

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