INS-1 — Approval, Listing, Labeling, and Instructions

Approval is an installation decision

Under 2017 NEC 110.2, conductors and equipment required or permitted by the Code are acceptable only if approved. Article 100 defines approved as acceptable to the authority having jurisdiction (AHJ). The AHJ can be an organization, office, or individual responsible for enforcing Code requirements or approving equipment, materials, installations, or procedures.

Approval, listing, and labeling are related but not interchangeable. A product's listing or label is important evidence that helps the AHJ evaluate suitability. It does not grant permission to use the product in any location, at any voltage, or for any purpose. The installation still must match the Code, the product markings, and the conditions under which the evaluation was made.

Distinguish the defined terms

Listed equipment is included in a list published by an organization acceptable to the AHJ. The organization performs product evaluation, maintains periodic inspection of production, and states that the equipment meets designated standards or was tested and found suitable for a specified purpose.

Labeled equipment bears a label, symbol, or other identifying mark of an organization acceptable to the AHJ. That organization evaluates the product and periodically inspects production; the marking indicates compliance with standards or performance in a specified manner.

Identified means recognizable as suitable for a specific purpose, function, use, environment, or application where a Code rule requires such suitability. Identification can be shown by listing, labeling, or other evidence acceptable to the AHJ. “Identified for the use” is narrower than “electrical equipment exists.”

Do not reduce these concepts to a brand logo. Read the complete mark and associated ratings. A listed dry-location enclosure does not become suitable outdoors because the internal device is listed. A connector listed for one cable type is not automatically identified for a different cable construction or conductor range.

Examine equipment under 110.3(A)

Section 110.3(A) identifies considerations used when evaluating equipment. These include suitability for installation and use in conformity with the Code; mechanical strength and durability; wire-bending and connection space; electrical insulation; heating effects and arcing; classification by type, size, voltage, current capacity, and specific use; and other factors affecting practical safeguarding.

The examination is contextual. A device can be well made yet unsuitable for the environment, available fault current, conductor material, or mounting method. Check:

• nominal voltage, current, frequency, and phase ratings;
• conductor material, size range, and terminal temperature limitations;
• wet, damp, corrosive, hazardous, or other environmental identification;
• enclosure type and physical-protection conditions;
• mounting orientation, ventilation, spacing, and accessory requirements; and
• short-circuit, interrupting, and other marked ratings.

Follow listing and labeling instructions

Under 2017 NEC 110.3(B), listed or labeled equipment must be installed and used in accordance with instructions included in the listing or labeling. The phrase “included in” matters. Advertising, optional suggestions, and unrelated product literature are not automatically listing conditions, but instructions supplied as part of the listing or labeling can be enforceable installation requirements.

Examples include a required mounting orientation, specified hub or fitting, permitted conductor range, torque value, maximum number of conductors, required barrier, or restriction to a dry location. If a terminal is identified for one conductor, landing two conductors under it is not acceptable merely because both physically fit. If equipment instructions require a particular accessory to maintain an enclosure rating, omitting it can defeat the identified use.

Manufacturer instructions do not authorize a Code violation. Both layers apply: the installation must comply with the NEC and with instructions included in the listing or labeling. Where instructions appear inconsistent or incomplete, do not invent a field modification; obtain the correct documentation and resolve acceptability with the AHJ or other responsible party.

Environmental suitability

Section 110.11 addresses deteriorating agents. Conductors and equipment cannot be located in damp, wet, corrosive, excessively hot, or otherwise damaging environments unless identified for the use. A weather-resistant cover alone does not prove that every internal component, raceway connection, conductor insulation, or mounting method is suitable. Examine the complete assembly.

An enclosure type marking describes specific protection capabilities. It is not a universal statement that the enclosure is explosionproof, corrosionproof, submersible, or suitable for every outdoor exposure. Match the identified type to the actual condition and preserve the rating by using appropriate openings, fittings, closures, and mounting.

Fault-current ratings

Under 110.9, equipment intended to interrupt current at fault levels must have an interrupting rating sufficient for the nominal circuit voltage and the current available at its line terminals. This primarily asks whether a fuse or circuit breaker can safely interrupt the prospective fault.

Section 110.10 addresses circuit impedance, short-circuit current ratings, and other characteristics. Equipment must be selected and coordinated so the protective device can clear a fault without extensive damage to the electrical equipment. A panelboard, disconnect, controller, or assembly can have a marked short-circuit current rating (SCCR) that must not be less than the available fault current under the applied system conditions. Interrupting rating and SCCR are not synonyms.

Example: assume 22,000 A of available fault current at 240 V. A breaker with a 10,000 A interrupting rating is inadequate at that location even if its normal ampere rating matches the load. Likewise, a 10 kA-rated assembly is not made adequate merely by installing a breaker with a higher interrupting rating unless a listed and properly applied combination establishes the assembly rating. Check the entire system, markings, and instructions.