Okay, let's clarify the situation with set-screw EMT connectors under the 2023 NEC, focusing on your specific aircraft hangar scenario.

General NEC Position on EMT Connectors (Regardless of Year, Including 2023) Permitted

The NEC does generally permit set-screw EMT connectors for most applications. There isn't a blanket prohibition. However, there are specific exceptions and requirements related to grounding, location, and listing that can affect their acceptability.

Key Considerations & NEC Sections (2023 NEC unless otherwise specified)


Grounding

This is the most critical factor.

314.4(E) Metal Boxes. Where a raceway or cable with metal armor or sheath is connected to a metal enclosure, it shall comply with 250.8 and 250.
9. 250.8 Methods of Grounding and Bonding. The connection of a grounding electrode conductor shall be in accordance with 250.8(A) through (E). 250.9 Bonding of Piping Systems and Exposed Structural Metal.2. Listing and Suitability (110.3(B))

All electrical equipment, including EMT connectors, must be listed by a recognized testing laboratory (e.g., UL, ETL). The listing will specify the conditions under which the connector is suitable for use. The connector must be suitable for the environment. In your case, that includes considering whether it's subject to physical damage or corrosive substances (common in some hangars).3.

Corrosive Environments (300.6)

Even if the location isn't technically "wet," aircraft hangars can sometimes have corrosive conditions due to fuel, cleaning agents, or other chemicals. 300.6 requires materials suitable for the environment. Standard steel set-screw connectors might not be the best choice in a highly corrosive environment.
4.

Tightening (General Good Practice)

Regardless of the connector type, proper tightening is crucial for both mechanical integrity and electrical continuity. Follow the manufacturer's instructions.

Applying This to Your Aircraft Hangar Scenario

Based on your description:

Inside a Hangar

You state it's indoors and not in a wet location. This is a positive factor toward using set-screw connectors, but you still need to consider other factors.

Not Used for Grounding Purposes

If the conduit is not intended to serve as the equipment grounding conductor (EGC), the grounding requirements are less stringent.

Corrosion

Carefully consider whether the hangar environment is corrosive. If there are potential corrosive substances present, you might need to upgrade to stainless steel or another corrosion-resistant connector type.

Important Caveats and Best Practices



AHJ Authority

The final decision always rests with the Authority Having Jurisdiction (AHJ), the local electrical inspector. They can have local amendments to the NEC or interpretations based on specific conditions.

Engineer's Specifications

If the project was designed by an engineer, their specifications would take precedence over general NEC rules (assuming they meet minimum code requirements).

Better Practice

While set-screw connectors can be code-compliant in some situations, compression connectors are often considered a better practice. They generally provide a more secure mechanical connection and a potentially better electrical connection (especially important if the EMT is used as the EGC). Many electricians prefer compression connectors for their reliability.

Recommendation


Check the Project Specifications

Review any engineering drawings or specifications for the project. If they call for compression connectors, you must use them.2.

Assess the Environment

Closely examine the hangar environment for potential corrosive substances.3.

Consult the AHJ

The best course of action is to discuss your specific situation with the local electrical inspector. They can provide definitive guidance based on local interpretations and conditions.4.

Consider Upgrading

Even if set-screw connectors are technically permissible, strongly consider upgrading to compression connectors for the added reliability and robustness, especially if corrosion is a concern.

In summary, set-screw EMT connectors are not universally banned by the 2023 NEC. However, their acceptability depends on proper grounding, suitability for the environment, listing requirements, and the AHJ's interpretation. Given the potential for corrosion and the importance of reliable electrical connections in an aircraft hangar, compression connectors are often a better choice, even if not strictly required by code.Disclaimer: I am an AI chatbot and cannot provide professional electrical advice. Always consult with a qualified electrician and your local AHJ for code-compliant installations. Flag for review