Okay, let's break down this situation and find the relevant NEC sections. You're right to question the contractor's blanket statement of "illegal" because your described setup is likely permissible, but there are nuances.

Here's the scenario as you describe it



Conduit System

Intermediate Metal Conduit (IMC) is the wiring method, serving as the equipment grounding conductor (EGC). This is a permitted method.

Fan Wiring

Romex (NM-B cable) is used for the fan wiring.

Grounding

The Romex ground wire is connected to the metal (presumably grounded) gang box serving as the point of connection to the EGC.

Why the Contractor Might Be Concerned (and why he's likely wrong in stating that it's illegal)

The contractor's concern likely stems from a misunderstanding about the proper termination of grounding conductors when mixing wiring methods. Here's what he might be thinking:1.

Grounding Integrity

He might be concerned that simply wrapping the Romex ground around a screw on the metal box isn't sufficient for a reliable ground connection,

ESPECIALLY if the box isn't properly bonded to the conduit system. A loose connection could compromise safety.2. NEC 314.4 Hubs He may not understand that hubs are not required for conduit to a box and see that as "wrong."Relevant NEC Sections to Review

Here are the key NEC sections that apply. You'll need to consult the current edition of the NEC in your jurisdiction. I'm referencing the 2023 NEC.

Always refer to the local AHJ (Authority Having Jurisdiction) for the final determination.1. NEC 250.4(A)(5) and (B)(4): Electrical System Grounding and Bonding. This section lays the foundation. It emphasizes the need for a permanent and continuous grounding path capable of handling likely fault currents. The conduit system, when properly installed, fulfills this requirement.2. NEC 250.8 Connection of Grounding and Bonding Equipment. This section lists acceptable methods for connecting grounding conductors to equipment and to each other. Importantly, it doesn't prohibit using the metal box as a junction point for the Romex ground, provided the connection is reliable and secure.3. NEC 250.118 Types of Equipment Grounding Conductors

IMC is listed as an acceptable EGC.4.

NEC 250.130 Equipment Grounding Conductor Connections. This section deals with grounding equipment connected by cord and plug or by fixed wiring methods. 250.130(C) specifically talks about extending the ground to a replacement receptacle or equipment in existing installations. While not a direct reference to your situation, it underscores the general principle of maintaining a continuous ground.
5. NEC 300.3(B) Conductors of Different Systems Section talks about different wiring methods used in raceways and enclosures. It states that conductors of different wiring methods must be rated for the maximum voltage applied. As long as you are within the voltage rating and you are maintaining a good, solid ground, it is fine.6. NEC 314.4(D) Metal Boxes. This section specifically addresses the use of metal boxes. It requires that where a metal box is used with nonmetallic cable (like Romex), provisions must be made for connecting an equipment grounding conductor to the box. This often involves a grounding screw or clip inside the box. Your scenario describes this, but it's crucial to ensure the connection is secure and properly made.7. NEC 314.40(D) Wiring Devices with Integral Enclosures. This section allows you to connect to the box if you have equipment listed for grounding.

Key Considerations & Best Practices



Proper Grounding Screw

Use a listed grounding screw (usually green) in the metal box specifically designed for grounding. Don't just wrap the wire around a random screw.

Bonding Jumper (If Necessary)

In some cases, depending on the specific box and how it's connected to the conduit, a bonding jumper wire might be needed to ensure a solid electrical connection between the box and the conduit. The AHJ can provide guidance on this.

Tight Connections

Ensure all connections are tight and corrosion-free. Loose connections defeat the purpose of the grounding system.

AHJ is King

Ultimately, the local electrical inspector (AHJ) has the final say. If there's any doubt, discuss the situation with them and get their opinion before the work is completed.

Why the Contractor is Likely Overstating the Issue

The use of Romex in a conduit system is common, especially for short runs like connecting to a fan. As long as the grounding conductor in the Romex is properly connected to the metal box, which is in turn properly grounded via the conduit system, the setup is generally compliant with the NEC. The key is the quality of the ground connection.

In Summary

Your assessment is likely correct. The contractor's blanket statement of "illegal" is probably an oversimplification. The setup can be code-compliant, provided the grounding connections are made properly, securely, and in accordance with the NEC and local amendments.

Action Steps


Review the NEC

Get the current edition of the NEC and read the sections I've cited.2.

Inspect the Connections

Ensure the Romex ground wires are connected to the metal boxes using listed grounding screws, and that the screws are tight. Inspect the connection of the metal conduit to the metal box to verify that the grounding plane is continuous.3.

Consult the AHJ

If you're still unsure, contact your local electrical inspector (AHJ) and discuss the situation. Show them the wiring setup and ask for their opinion. Getting their approval before the drywall goes back up is the best course of action.4.

Document Everything: Keep a record of your conversations with the contractor and the AHJ. Take photos of the wiring before* it's covered up.By doing your homework and consulting with the relevant authorities, you can ensure the wiring is safe, compliant, and meets your professional standards. Good luck! Flag for review