You've hit on a point of frequent discussion and some ambiguity within the NEC. You are correct that the NEC doesn't explicitly and universally mandate "Listed and Labeled" for all electrical equipment in every situation. Here's a breakdown of why your observations are accurate and where the "Listed and Labeled" requirement derives its strength

The Key Areas and Nuances:
Article 110.3(A) Examination, Identification, Installation, and Use. This is a crucial section. It doesn't say "Listed and Labeled" outright, but it states: "Equipment shall be firmly secured to the surface on which it is mounted." "Electrical equipment shall be installed and used in accordance with any instructions included in the listing or labeling."This section essentially says that IF equipment is Listed and Labeled, the installation must follow the Listing/Labeling instructions. This implies that Listing and Labeling is preferred but not necessarily required. Article 110.2 Approval. This section uses the term "Approved." "The conductors and equipment required or permitted by this Code shall be acceptable only if approved." "Equipment shall be acceptable if it is listed, labeled, or identified."This is where the concept of "Approved" comes into play. "Approved" is defined in Article 100 as "Acceptable to the Authority Having Jurisdiction (AHJ)." The AHJ has the final say on what's acceptable, and they often rely heavily on Listing and Labeling as evidence of safety and compliance with standards. Definition of "Listed" (Article 100)

"Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that the equipment, material, or services either meets appropriate designated standards or has been tested and found suitable for a specified purpose."

Definition of "Labeled" (Article 100)

"Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner."

Why "Listed and Labeled" is Strongly Encouraged (and often Required in Practice)


AHJ Acceptance

The AHJ has broad authority to determine what is "approved." Because Listing and Labeling by a reputable organization (like UL, ETL, CSA) provide independent verification that the equipment meets recognized safety standards, the AHJ will almost always accept Listed and Labeled equipment. This significantly reduces the risk of rejection.2.

Manufacturer's Instructions

As mentioned in 110.3(B), equipment must be installed and used in accordance with the manufacturer's instructions (which are often part of the Listing). Failure to do so can void the Listing and potentially create a safety hazard.
3.

Liability

Using unlisted or unlabeled equipment significantly increases liability in case of an incident. Insurance companies and legal teams will scrutinize whether equipment was properly Listed and Installed per the Listing Instructions.4.

Specific Equipment Requirements

While a blanket statement is difficult to find, many articles do require specific types of equipment to be Listed. Examples include:

Article 210.8(B)

Ground-Fault Circuit-Interrupter (GFCI) protection for personnel is required.

Article 406.4(D)

Receptacles installed in countertop surfaces in dwelling units.

Article 408.54

Overcurrent devices used in panelboards.These articles often don't explicitly say "Listed," but they require compliance with specific UL standards, effectively mandating Listing by any organization that tests to those standards.5.

Practical Considerations

In most cases, it's simply impractical to use unlisted equipment. Obtaining approval from the AHJ for unlisted equipment would require extensive documentation, testing, and justification, which is often more costly and time-consuming than using a Listed product.

In Summary

The NEC doesn't have a single, overarching statement that all equipment must be Listed and Labeled. The NEC uses terms like "Approved" and emphasizes following manufacturer's instructions. "Approved" is defined by the AHJ, who typically favors Listed and Labeled equipment. Many specific articles effectively require Listing by referencing specific standards. Using Listed and Labeled equipment significantly reduces liability and simplifies the approval process.

The takeaway is this

While you are technically correct that a universal "Listed and Labeled" mandate is not explicitly stated, the NEC's structure and the practical realities of electrical work strongly favor and often effectively require the use of Listed and Labeled equipment. Choosing unlisted or unlabeled equipment is a risky proposition.

Recommendation:

Always strive to use Listed and Labeled equipment whenever possible. It's the safest, most reliable, and most easily approved approach. If you are considering using unlisted equipment, consult with the AHJ before proceeding to understand their requirements for approval. Good Luck and stay safe. Flag for review