You're on the right track! Let's break this down and get you pointed to the right code sections.

Your Initial Assessment (250.32(B)(1)): Excellent call. You correctly identified that running a separate equipment grounding conductor (EGC) is mandatory for a detached building with a feeder. The homeowner absolutely cannot use the neutral as the EGC in this scenario.

Why What He Did is Wrong (Expanded): 250.32(A) General The grounding electrode system requirements of 250.50 shall comply and connect to the grounding electrode conductor. 250.32(B)(1) Detached Buildings or Structures Where supplied by a feeder or branch circuit, an equipment grounding conductor shall be installed. 250.32(B)(2) Grounded Systems Where the building or structure has a grounded system, a grounding electrode conductor shall be connected to the grounding electrodes as described in 250.50 and shall be used for grounding or bonding noncurrent-carrying metal parts of equipment, raceways, and other enclosures. 250.24(A)(5) The neutral conductor should never be used as an EGC on the load side.

Your Concern About the 2-Pole Breaker: This is a valid concern, and here's how to address it. 240.20 (B) Ungrounded Conductors Each ungrounded conductor shall have overcurrent protection at the point where the conductors receive their supply. 240.20(C) Grounded Conductors One pole of the circuit breaker may be connected to the grounded conductor, and in series with each ungrounded conductor. This is acceptable.

Additional Points to Consider: Improper Neutral Marking: Since it sounds like he re-taped the neutral as a hot leg. It need to be remarked for the new use and be colored or marked for identification (200.6) (Typically white or Gray)How to Explain This to the Homeowner

Explain that running a proper 4-wire (2 hots, neutral, ground) is essential for safety. Emphasize that it's not just about having power, but about safe power. Safety

A proper ground provides a low-impedance path for fault current, which allows the breaker to trip quickly and prevent dangerous voltage from appearing on metal enclosures.

Future Use

Even if he only plans to use 120V circuits now, having a 240V-capable feeder allows for future expansion (e.g., a welder, air compressor, EV charger).

Code Compliance

Explain that the NEC exists to protect people and property, and following the code ensures a safe and reliable electrical system.

Tips for New Inspectors: Keep Learning

The NEC changes every three years. Stay updated with code updates, industry best practices, and new technologies.

Document Everything

Take clear photos, write detailed notes, and document code violations with specific section numbers.*

Be Professional

Explain your findings clearly and respectfully to homeowners. Remember, they may not have a technical background.

In Summary: The homeowner's setup is incorrect and unsafe. He needs to run a proper 4-wire feeder with a dedicated EGC, ensure the panel is properly grounded at the detached garage, and avoid any scenarios where the neutral conductor is used as an EGC. Your initial instincts are correct, keep asking questions and keep learning. Flag for review