Article 100 NEC Definitions (Letter N)

This guide covers essential electrical terminology related to various systems, such as wind turbines, lighting, communication devices, and safety protocols.

It provides key definitions and standards to ensure proper installation and operation of these systems.

Nacelle
An enclosure housing the alternator and other parts of a wind turbine. (694) (CMP—4)

Neon Tubing
Electric-discharge luminous tubing, including cold cathode luminous tubing, manufactured into shapes to illuminate signs, form letters, parts of letters, skeleton tubing, outline lighting, decorative elements, or art forms, and filled with various inert gases. (600) (CMP—18)

Network Interface Unit (NIU)
A device that converts a broadband signal into component voice, audio, video, data, and interactive services signals and provides isolation between the network power and the premises signal circuits. These devices often contain primary and secondary protectors. (CMP—16)

Network Terminal
A device that converts network-provided signals (optical, electrical, or wireless) into component signals, including voice, audio, video, data, wireless, optical, and interactive services, and is considered a network device on the premises that is connected to a communications service provider and powered at the premises. (CMP—16)

Neutral Conductor
The conductor connected to the neutral point of a system intended to carry current under normal conditions. (CMP—5)

Neutral Point
The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system. (CMP—5)
Informational Note: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential.

Nonautomatic
Requiring human intervention to perform a function. (CMP—1)

Nonincendive Circuit
A circuit, other than field wiring, in which any arc or thermal effect produced under intended operating conditions of the equipment is not capable, under specified test conditions, of igniting the flammable gas-air, vapor-air, or dust-air mixture. (CMP—14)
Informational Note: See ANSI/UL 121201, Nonincendive Electrical Equipment for Use in Class I and II, Division 2 and Class III, Divisions 1 and 2 Hazardous (Classified) Locations for additional information.

Nonincendive Component
A component having contacts for making or breaking an incendive circuit, and the contacting mechanism is constructed so that the component is incapable of igniting the specified flammable gas-air or vapor-air mixture. The housing of such a component is not intended to exclude the flammable atmosphere or contain an explosion. (CMP—14)
Informational Note: See ANSI/UL 121201 for further details.

Nonincendive Equipment
Equipment having electrical/electronic circuitry that is incapable, under normal operating conditions, of causing ignition of a specified flammable gas-air, vapor-air, or dust-air mixture due to arcing or thermal means. (CMP—14)
Informational Note: See ANSI/UL 121201 for further details.

Nonincendive Field Wiring
Wiring that enters or leaves an equipment enclosure and, under normal operating conditions of the equipment, is not capable, due to arcing or thermal effects, of igniting the flammable gas-air, vapor-air, or dust-air mixture. Normal operation includes opening, shorting, or grounding the field wiring. (CMP—14)
Informational Note: See ANSI/UL 121201 for additional information.

Nonincendive Field Wiring Apparatus
Apparatus intended to be connected to nonincendive field wiring. (CMP—14)
Informational Note: See ANSI/UL 121201 for further information.

Nonlinear Load
A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage. (CMP—1)
Informational Note: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.

Nonmetallic Extension
An assembly of two insulated conductors within a nonmetallic jacket or an extruded thermoplastic covering. The classification includes surface extensions intended for mounting directly on the surface of walls or ceilings. (CMP—6)

Nonsparking
Constructed to minimize the risk of arcs or sparks capable of creating an ignition hazard during conditions of normal operation. (CMP—14)
Informational Note: See ANSI/UL 121201 for additional details.

Normal/Emergency Power Source
A power source on the output side of a transfer switch or uninterruptible power supply that is automatically available upon loss of normal power. (700) (CMP—13)

Normal High-Water Level (as applies to electrical datum plane distances)
Natural or Artificially Made Shorelines: An elevation delineating the highest water level maintained for a sufficient period of time to leave evidence upon the landscape.
Rivers and Streams: The elevation of the top of the bank of the channel, with considerations for flood-prone areas and water runoff.
Flood Control Bodies of Water: The flood pool maximum water surface elevation of a reservoir, equal to the elevation of the spillway.
Nonflood Control Bodies of Water: The flowage easement boundary, marking the highest water surface elevation in reservoirs. (CMP—7)

Nurses’ Station
A space intended to provide a center of nursing activity for a group of nurses serving bed patients, where activities such as patient calls, nurse dispatch, chart preparation, and medication distribution occur. If conducted in multiple locations, all such spaces are considered parts of the nurses’ station. (517) (CMP—15)

Nursing Home
A building or portion of a building used on a 24-hour basis for housing and nursing care of individuals unable to provide for their own needs due to physical or mental incapacity. (CMP—15)

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Summary Table:

Term	Definition
Nacelle	Enclosure housing the alternator and parts of a wind turbine. (694) (CMP—4)
Neon Tubing	Electric-discharge luminous tubing used for signs and decorative lighting. (600) (CMP—18)
Network Interface Unit (NIU)	Device converting broadband signal into component signals with isolation between network power and premises signal circuits. (CMP—16)
Network Terminal	Device converting network signals into component signals on the premises connected to a communication service provider. (CMP—16)
Neutral Conductor	Conductor connected to the neutral point of a system, intended to carry current under normal conditions. (CMP—5)
Neutral Point	The common point in a system where voltages from other phases are zero potential. (CMP—5)
Nonautomatic	Requiring human intervention to perform a function. (CMP—1)
Nonincendive Circuit	Circuit that under normal conditions cannot ignite a flammable mixture. (CMP—14)
Nonincendive Component	Component incapable of igniting a flammable gas-air mixture under normal conditions. (CMP—14)
Nonincendive Equipment	Equipment incapable of igniting a flammable mixture due to arcing or thermal means. (CMP—14)
Nonincendive Field Wiring	Wiring that cannot ignite a flammable mixture under normal operating conditions. (CMP—14)
Nonlinear Load	Load where current wave shape differs from applied voltage wave shape. (CMP—1)
Nonmetallic Extension	Assembly of insulated conductors in a nonmetallic jacket or covering. (CMP—6)
Nonsparking	Equipment designed to minimize ignition risk due to arcing or sparks. (CMP—14)
Normal/Emergency Power Source	Power source available upon loss of normal power. (700) (CMP—13)
Normal High-Water Level	Highest water level maintained for sufficient time to leave evidence, with consideration for flood-prone areas. (CMP—7)
Nurses’ Station	Central nursing space for various activities like chart preparation and medication distribution. (517) (CMP—15)
Nursing Home	Facility providing 24-hour care for individuals unable to care for themselves. (CMP—15)