NFPA 70: National Electrical Code

NFPA 70 or Nationl Electrical Code is the reference standard for electrical installations in premises and buildings in USA.

Being an Installation Code, it is addressed to the installer, more than to the Electrical Engineer who designs the electrical installation/distribution.

The first National Electrical Code was developed in 1897. In 1911, the National Fire Protection Association (NFPA) became the sponsor, and the Code has been revised on numerous occasions since that date. Now it is revised every three years. The latest edition is 2020. The NEC is available for adoption as the electrical law in a governmental jurisdiction. That governmental jurisdiction may add one or more amendments to allow for local needs, preferences, or conditions (see for example the Chicago Electrical Code).

The code was born soon after Thomas A. Edison’s Pearl Street Station was installed in New York City in 1882. Electrical fires were becoming commonplace and, by 1897, the problem was reaching epidemic proportions. A diverse group of knowledgeable, concerned individuals assembled to address this critical issue. The need for standardization was apparent. The consensus of more than 1200 individuals produced the first set of nationally adopted rules to govern electrical installations and operations: the National Electrical Code was born. The NEC states its purpose as “the practical safeguarding of persons and property from hazards arising from the use of electricity“. This objective has remained constant throughout the NEC’s existence, and the principles it contains continue to grow and change with the dynamic electrical industry.

The NFPA 70 or NEC is the reference standard for several electrical standards among which:

• UL 508A: the product standard for Industrial Control Panels
• NFPA 79: the reference for the electrical installations in Machineries

There are 2 main articles in the NEC dealing with Machinery:

• Article 409: Industrial Control Panels
• Article 670: Industrial Machinery

The latest Edition of the standard is the 2026, published in October 2025. Hereafter the key changes having a possible impact to the Electrical Equipment of Machinery.

High-voltage systems are given significantly more attention. Chapter 2 (Wiring and Protection) includes sections dedicated exclusively to installations exceeding 1,000 V AC and 1,500 V DC:

• Article 265: General Requirements for Branch
• Article 266: Installation requirements, overcurrent protection, and conductor ratings for feeders.
• Article 267: Branch circuits and outdoor feeders installed on or between buildings, structures, or poles.
• Article 268: Conductors and Service Entrance/Service Equipment.
• Article 270: Grounding and Bonding.

At the same time, Chapter 4 (Article 495) has been updated to include specific requirements for equipment operating at voltages greater than 1000 V_acand 1500 V_dcregarding:

• Disconnecting devices and grounding switches.
• Requirements for installations on flammable floors.
• Presence of visual inspection windows.
• Isolation means for high-voltage mobile/portable equipment and liquid-filled equipment.

The NEC defines “Reconditioned Equipment” as any electromechanical equipment or component restored to operating condition. This process differs from normal routine on-site maintenance.

[NEC 2026] 100 Reconditioned Equipment

Electromechanical systems, equipment, apparatus, or components that are restored to operating conditions. This process differs from normal servicing of equipment that remains within a facility, or replacement of listed equipment on a one-to-one basis.

To ensure adequate safety levels, the use of reconditioned equipment is no longer permitted for the following categories:

• Cables and conduits: Article 300.4 reiterates the requirement to completely replace conductors and wiring methods damaged by overheating, fire, corrosive substances, or water.
• Electrical distribution panels.
• Electrical cables for space heating and fixed outdoor equipment for defrosting/snow melting.
• Phase converters, capacitors, and resistors.
• High-voltage equipment (>1000 V AC / 1500 V DC), except for switching equipment.
• Energy storage systems (BESS).
• Primary and secondary protection for limited-energy systems.

A specific entry for cable ties has been added to the definitions chapter, defined as fasteners used to bundle, secure, and/or support cables and flexible conduits.

For the North American market, cable ties must be certified. Since the certification mark is often located on the packaging rather than on the individual item, it is recommended to retain the packaging or photograph the NRTL mark to facilitate verification during Field Evaluation/Field Certification.

[NEC 2026] 100 Cable ties

A band or length of material employing a locking device, used for bundling, securing, and/or supporting cable, flexible conduit, or flexible tubing.

Informational Note:

The following are cable tie and cable tie fixing device type designations:

• Type(s) 1, 11, 2, 21, 2S, or 21S are evaluated for use in cable management applications.

• Type(s) 2S or 21S are also evaluated for securing and supporting cable, flexible conduit, and flexible tubing.

There are two types of labels related to arc flash hazards:

1. Arc Flash Warning Label: Affixed by the panel manufacturer, this is a general hazard warning.
2. Arc-Flash Hazard Marking: The responsibility of the end user, it provides specific data from the arc energy calculation.

Until the 2023 edition, the information required on the second type of label—the one the end user is responsible for—was not specified. The new edition, however, clarifies what information must be included.

The field-mounted label must comply with NEC 110.21(B), be clearly visible, and must include the following:

1. Nominal system voltage.
2. Arc flash boundary.
3. Available incident energy or the minimum level of PPE required.
4. Date of completion of the risk assessment.

[NEC 2026] 110.16 Arc-Flash Hazard Marking.

In other than dwelling units, a permanent arc flash marking shall be field or factory applied to service equipment and feeder-supplied equipment, such as switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures, and motor control centers that are likely to require examination, adjustment, servicing, or maintenance while energized. The marking shall comply with 110.21(B), be located so as to be clearly visible to qualified persons, and be in accordance with applicable industry practice, containing the following information:

1. The nominal system voltage
2. The arc flash boundary
3. The available incident energy or minimum required level of personal protective equipment
4. The date the assessment was completed

Informational Note No. 1:

See ANSI Z535.4-2011 (R2017), Product Safety Signs and Labels, for guidelines for the design of safety signs and labels for application to products.

Informational Note No. 2:

See NFPA 70E, Standard for Electrical Safety in the Workplace, for applicable industry practices for equipment marking. This standard provides specific criteria for developing arc-flash labels for equipment that provides nominal system voltage, incident energy levels, arc-flash boundaries, minimum required levels of personal protective equipment, and so forth.

To prevent threaded protective conduits from being secured to boxes or enclosures using a single internal locknut—a practice that can cause mechanical loosening and damage cable insulation—Article 342.29 has been introduced

[NEC 2026] 342.29 Paired Locknuts

If conduit threads enter a box, cabinet, or similar enclosure through an opening other than a threaded opening, a locknut or fitting shall be installed on the inside and outside of the enclosure.

Article 392.18 introduces a specific dimensional requirement to ensure personnel safety during cable installation and maintenance.

[NEC 2026] 392.18 Cable Tray Installation

A minimum access space of 300 mm (12 in.) above cable trays shall be provided and maintained to allow access for installing and maintaining the cables.

Exception No. 1: Where the installation complies with 645.5 for IT equipment rooms.

Exception No. 2: In industrial facilities, where maintenance and supervision procedures ensure that only qualified personnel service the installed cable tray.

Exception No. 3: By special permission, smaller clearance distances may be permitted.

Exception No. 4: For equipment crossing at any angle.

The section on short-circuit current (SCCR) has been reorganized into a five-point bulleted list.

Electrical panels must display, in an easily accessible location on the enclosure, the available fault current at the input terminals along with the date of the calculation, together with the panel’s short-circuit withstand rating (SCCR) based on the installed circuit breakers. These labels must be durable, and the fault current calculation must be formally documented and made available to inspectors. In the event of system modifications that alter the available fault current, it is mandatory to recalculate the value, update the label, and ensure that any added or replaced circuit breakers have a breaking capacity equal to or greater than the stated value.

[NEC 2026] Short-Circuit Current Rating.

Switchboards, switchgear, and panelboards shall have a short-circuit current rating not less than the available fault current. In buildings other than one- and two-family dwellings, switchboards, switchgear, and panelboards shall comply with the following, as applicable:

1. The available fault current at the line terminals and the date the calculation was performed shall be field-marked in a readily accessible location on the enclosure at the point of supply.
2. The short-circuit current rating of switchboards and panelboards, at nominal circuit voltage, based on the OCPDs installed, shall be field-marked in a readily accessible location on the enclosure.
3. The marking required by 408.6(1) and 408.6(2) shall comply with 110.21(B).
4. The calculation of the available fault current shall be documented and made available to those authorized to inspect, install, or maintain the installation.
5. When modifications to the electrical installation occur that affect the available fault current at the line terminals of the equipment, the following shall apply:
   • The available fault current shall be verified or recalculated as necessary to ensure that the equipment ratings are not less than the available fault current at the line terminals of the equipment.
   • The required field markings specified in 408.6(1) shall be adjusted to reflect the new level of available fault current.

When OCPDs are added or replaced, the interrupting rating of the replacement OCPDs shall be equal to or greater than the available fault current marked on the equipment in accordance with 408.6(1).

Regulations for new ultra-high-efficiency motors (Energy Efficient, an evolution of Designs B and C) are introduced. The conductors supplying a single BE or CE motor in continuous service must have an ampacity of not less than 125 percent of the full-load current.

[NEC 2026] 430.22 (H) Design BE and CE Motors.

Conductors that supply a single Design BE or CE motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1). Conductors that supply a single Design BE or CE motor used in an application other than continuous duty shall have an ampacity per 430.22(E). […]

The same section also introduces a specification regarding the identification of motor control centers (MCCs). For MCCs powered by external feeders and lacking a single main circuit breaker on board, an important safety requirement is introduced: the panel must be equipped with a clear label, in accordance with the provisions of Article 110.21(B), indicating the exact identification and location of the remote device or devices necessary to isolate and de-energize the entire panel.

[NEC 2026] 430.98 (A) Marking.

Motor control centers shall be marked in accordance with 110.21, and the marking shall be plainly visible after installation. Marking shall also include common power bus current rating and motor control center short-circuit current rating. Where supplied by a feeder(s), motor control centers shall be marked in accordance with 110.21(B) with the identification and location(s) of the means necessary to disconnect all power to the motor control center.