You are correct in your interpretation of NEC 200.7. This section does not apply to NM cable (Romex).Here's a breakdown of why: 200.7 talks about "conductors." While NM cable contains conductors, 200.7 specifically refers to individual conductors that are part of a flexible cord, fixture wire, or other specifically listed types. It's about identifying the intended use of individual conductors, not repurposing the entire neutral of an NM cable run. NM Cable already has an identified neutral. NM cable is required to have a white or gray conductor for use as the grounded (neutral) conductor. Changing the purpose of the white conductor in an NM cable run that's not specifically intended for use as a grounded conductor would violate the inherent design and safety features of the cable. NEC 334.10(3) Uses Permitted NM cable can be used for exposed and concealed work in normally dry locations. NEC 334.12 Uses Not Permitted NM cable shall not be used in the following locations or under the following conditions: (6) Where exposed to corrosive fumes or vapors. (11) Direct burial in the earth.

Here's why re-identifying the white wire in your scenario is a violation


Improper Use of NM Cable

Using NM cable with the intention of re-identifying the white wire as a hot conductor violates the listing and purpose of the cable. NM cable is designed for specific wiring configurations, and altering them compromises its safety.2.

Misuse of the Neutral

The white wire in NM cable is intended as the grounded (neutral) conductor. Repurposing it for other uses, particularly a hot conductor, creates a safety hazard because the insulation is not designed for that purpose.3.

Lack of proper marking

If the white wire of the NM cable is being re-identified to serve as an ungrounded conductor (hot), then it is a violation of 200.7.

What the builder should have done



Used the correct cable

The builder should have used the correct cable type that contains conductors with the correct color coding. Acceptable options would include MC cable, or running individual THHN conductors in conduit. MC cable typically provides three conductors, black, white, and green.

Used three-wire NM cable

If NM cable were necessary for some odd reason, the builder should have used 10/3 NM cable (black, white, red, and bare ground) for the application and left the white conductor unused and capped off.

In summary:

You are correct. NEC 200.7 does not apply to NM cable. Re-identifying the white wire in NM cable to serve as a hot conductor for an AC condenser installation is a violation of the NEC and a safety hazard. The builder needs to use the correct cable type, properly rated for the intended use, and with conductors of the correct color.Make sure to document your findings clearly, citing the specific violations (misuse of NM cable, improper use of the neutral conductor). Flag for review