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ons service provider and is powered at the premises. (CMP-16) Neutral Conductor. The conductor connected to the neutral point of a system that is 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 sing...

ons service provider and is powered at the premises. (CMP-16) Neutral Conductor. The conductor connected to the neutral point of a system that is 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. ENHANCED CONTENT Collapse The following exhibit illustrates four examples of a neutral point in a system. 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. ENHANCED CONTENT Collapse A nonincendive circuit employs a protection technique that prevents electrical circuits from causing a fire or explosion in a hazardous location under normal conditions. This is in contrast to an intrinsically safe circuit, whose evaluation is conducted under abnormal conditions. Because of its definition, a nonincendive circuit is a low-energy circuit, but many low-voltage, low-energy circuits, including some communications circuits and thermocouple circuits (or Class 2 or 3 circuits as defined in Article 725), are not necessarily nonincendive. 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, 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 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, 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 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, 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. ENHANCED CONTENT Collapse Field wiring meeting this definition requires limitations of energy under normally expected conditions of operation, such as opening, shorting, or grounding. For example, stored energy in the form of mutual inductance or capacitance could be released during an opening, shorting, or grounding of nonincendive field wiring, which defeats the purpose of this protection technique. Nonincendive Field Wiring Apparatus. Apparatus intended to be connected to nonincendive field wiring. (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. 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. ENHANCED CONTENT Collapse Nonlinear loads are a major cause of harmonic currents. Additional conductor heating is just one of the undesirable operational effects associated with harmonic currents. Informational Note No. 1(2) following 310.14(A)(3) points out that harmonic current is one of the factors that must be considered when determining the heat generated internally in a conductor. Actual circuit measurements of current for nonlinear loads should be made using only true root-mean-square (rms) measuring ammeter instruments. Averaging ammeters produces inaccurate values if used to measure nonlinear loads. See also 310.15(E)(3) and its enhanced content for more on 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, 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. 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 that has been maintained for a sufficient period of time to leave evidence upon the landscape, commonly the point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial. Rivers and Streams: The elevation of the top of the bank of the channel. Streams, rivers, and tributaries that are prone to flooding and effects of water runoff shall consider the “bankfull stage” where an established gauge height at a given location along a river or stream, above which a rise in water surface will cause the river or stream to overflow the lowest natural stream bank somewhere in the corresponding reach. 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 in which the highest water surface elevation defined by the area existing between governmental-owned property line(s) and a contour line with perpetual rights to flood the area in connection with the operation of the reservoir. (CMP‐7) Nurses’ Station. A space intended to provide a center of nursing activity for a group of nurses serving bed patients, where patient calls are received, nurses dispatched, nurses’ notes written, inpatient charts prepared, and medications prepared for distribution to patients. Where such activities are carried on in more than one location within a nursing unit, all such separate spaces are considered a to be parts of the nurses’ station. (517) (CMP-15) Nursing Home. A building or portion of a building used on a 24-hour basis for the housing and nursing care of four or more persons who, because of mental or physical incapacity, might be unable to provide for their own needs and safety without the assistance of another person. [101:3.3.150.2] (CMP-15) Office Furnishing. Cubicle panels, partitions, study carrels, workstations, desks, shelving systems, and storage units that may be mechanically and electrically interconnected to form an office furnishing system. (CMP-18) Oil Immersion. Electrical equipment immersed in a protective liquid so that an explosive atmosphere that might be above the liquid or outside the enclosure cannot be ignited. (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. Open Wiring on Insulators. An exposed wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors run in or on buildings. (CMP-6) Operating Device. The car switch, pushbuttons, key or toggle switch(s), or other devices used to activate the operation controller. (620) (CMP-12) Operator. The individual responsible for starting, stopping, and controlling an amusement ride or supervising a concession. (525) (CMP-15) Optical Radiation. Electromagnetic radiation at wavelengths in vacuum between the region of transition to X-rays and the region of transition to radio waves that is approximately between 1 nm and 1000 μm. (CMP-14) Informational Note: See ANSI/UL 60079-28, Explosive Atmospheres — Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation, for information on types of protection that can be applied to minimize the risk of ignition in explosive atmospheres from optical radiation in the wavelength range from 380 nm to 10 μm. Optical Radiation, Inherently Safe “op is”. (Inherently Safe Optical Radiation “op is”) Type of protection to minimize the risk of ignition in explosive atmospheres from optical radiation where visible or infrared radiation is incapable of producing sufficient energy under normal or specified fault conditions to ignite a specific explosive atmosphere. (CMP-14) Informational Note: See ANSI/UL 60079-28, Explosive Atmospheres — Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation, for additional information. Optical Radiation, Protected “op pr”. (Protected Optical Radiation “op pr”) Type of protection to minimize the risk of ignition in explosive atmospheres from optical radiation where visible or infrared radiation is confined inside optical fiber or other transmission medium under normal constructions or constructions with additional mechanical protection based on the assumption that there is no escape of radiation from the confinement. (CMP-14) Informational Note: See ANSI/UL 60079-28, Explosive Atmospheres — Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation, for additional information. Optical System With Interlock “op sh”. Type of protection to minimize the risk of ignition in explosive atmospheres from optical radiation where visible or infrared radiation is confined inside optical fiber or other transmission medium with interlock cutoff provided to reliably reduce the unconfined beam strength to safe levels within a specified time in case the confinement fails and the radiation becomes unconfined. (CMP-14) Informational Note: See ANSI/UL 60079-28, Explosive Atmospheres — Part 28: Protection of Equipment and Transmission Systems Using Optical Radiation, for additional information. Optional Standby Systems. Those systems intended to supply power to public or private facilities or property where life safety does not depend on the performance of the system. These systems are intended to supply on-site generated or stored power to selected loads either automatically or manually. (CMP-13) Organ, Electronic. (Electronic Organ) A musical instrument that imitates the sound of a pipe organ by producing sound electronically. (CMP-12) Informational Note: Most new electronic organs produce sound digitally and are called digital organs. Organ, Pipe. (Pipe Organ) A musical instrument that produces sound by driving pressurized air (called wind) through pipes selected via a keyboard. (CMP-12) Organ, Pipe Sounding Apparatus. (Pipe Organ Sounding Apparatus) (Pipe Organ Chamber). The sound-producing part of a pipe organ, including, but not limited to, pipes, chimes, bells, the pressurized air- (wind-) producing equipment (blower), associated controls, and power equipment. (CMP-12) Outlet. A point on the wiring system at which current is taken to supply utilization equipment. (CMP-1) ENHANCED CONTENT Collapse The term outlet is frequently misused to refer to receptacles. Although receptacle outlets are outlets, not all outlets are receptacle outlets. Other common examples of outlets include appliance outlets, lighting outlets, and smoke alarm outlets. Outlet Box Hood. A housing shield intended to fit over a faceplate for flush-mounted wiring devices, or an integral component of an outlet box or of a faceplate for flush-mounted wiring devices. The hood does not serve to complete the electrical enclosure; it reduces the risk of water coming in contact with electrical components within the hood, such as attachment plugs, current taps, surge protective devices, direct plug-in transformer units, or wiring devices. (CMP-18) Outline Lighting. An arrangement of incandescent lamps, electric-discharge lighting, or other electrically powered light sources to outline or call attention to certain features such as the shape of a building or the decoration of a window. (CMP-18) ENHANCED CONTENT Collapse Outline lighting includes low-voltage, light-emitting diodes (LEDs), as well as other luminaires installed to form various shapes. For outline lighting requirements, see Article 600. Output Cable to the Electric Vehicle. An assembly consisting of a length of flexible EV cable and an electric vehicle connector (supplying power to the electric vehicle). (625) (CMP-12) Output Cable to the Primary Pad. A multiconductor, shielded cable assembly consisting of conductors to carry the high-frequency energy and any status signals between the charger power converter and the primary pad. (625) (CMP-12) Overcurrent. Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault. (CMP-10) Informational Note: A current in excess of rating may be accommodated by certain equipment and conductors for a given set of conditions. Therefore, the rules for overcurrent protection are specific for particular situations. Overcurrent Protective Device, Branch-Circuit. (Branch-Circuit Overcurrent Protective Device) A device capable of providing protection for service, feeder, and branch circuits and equipment over the full range of overcurrents between its rated current and its interrupting rating. (CMP-10) ENHANCED CONTENT Collapse The protection provided may be overload, short-circuit, or ground-fault, or a combination, depending on the application. Overcurrent Protective Device, Current-Limiting. (Current-Limiting Overcurrent Protective Device) A device that, when interrupting currents in its current-limiting range, reduces the current flowing in the faulted circuit to a magnitude substantially less than that obtainable in the same circuit if the device were replaced with a solid conductor having comparable impedance. (240) (CMP-10) ENHANCED CONTENT Collapse A current-limiting protective device is one that cuts off a fault current in less than one-half cycle, thus preventing short-circuit currents from building up to their full available values. Most electrical distribution systems can deliver high ground-fault or shortcircuit currents to components such as conductors and service equipment. Those components can be damaged or destroyed by high fault currents, resulting in serious burndowns and fires. Properly selected current-limiting OCPDs, such as the Class R current-limiting fuses shown below with a rejection feature to prohibit the installation of non–current-limiting fuses, limit the let-through energy to an amount that does not exceed the rating of the components in spite of high available short-circuit currents. (Courtesy of Eaton, Bussmann Division) Overcurrent Protective Device, Supplementary. (Supplementary Overcurrent Protective Device) A device intended to provide limited overcurrent protection for specific applications and utilization equipment such as luminaires and appliances. This limited protection is in addition to the protection provided in the required branch circuit by the branch-circuit overcurrent protective device. (CMP-10) ENHANCED CONTENT Collapse The definition of supplementary overcurrent protective device makes two important distinctions between OCPDs. First, the use of a supplementary device is specifically limited to a few applications. Second, where it is used, the supplementary device must be in addition to and protected by the more robust branch-circuit OCPD. The devices used to provide overcurrent protection are different, and the differences are found in the product standards UL 489, Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures, and UL 1077, Supplementary Protectors for Use in Electrical Equipment. Overhead Gantry. A structure consisting of horizontal framework, supported by vertical columns spanning above electrified truck parking spaces, that supports equipment, appliances, raceway, and other necessary components for the purpose of supplying electrical, HVAC, internet, communications, and other services to the spaces. (626) (CMP-12) Overload. Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of its ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload. (CMP-10) Packaged Therapeutic Tub or Hydrotherapeutic Tank Equipment Assembly. A factory-fabricated unit consisting of water-circulating, heating, and control equipment mounted on a common base, intended to operate a therapeutic tub or hydrotherapeutic tank. Equipment can include pumps, air blowers, heaters, lights, controls, sanitizer generators, and so forth. (680) (CMP-17) Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet, enclosure, or cutout box placed in or against a wall, partition, or other support; and accessible only from the front. (CMP-9) Panelboard, Enclosed. (Enclosed Panelboard) An assembly of buses and connections, overcurrent devices, and control apparatus with or without switches or other equipment, installed in a cabinet, cutout box, or enclosure suitable for a panelboard application. (CMP-9) Park Electrical Wiring Systems. All of the electrical wiring, luminaires, equipment, and appurtenances related to electrical installations within a mobile home park, including the mobile home service equipment. (550) (CMP-7) Park Trailer. A unit that is built on a single chassis mounted on wheels and has a gross trailer area not exceeding 37 m2 (400 ft2) in the set-up mode. (552) (CMP-7) Part-Winding Motors. A part-winding start induction or synchronous motor is one that is arranged for starting by first energizing part of its primary (armature) winding and, subsequently, energizing the remainder of this winding in one or more steps. A standard part-winding start induction motor is arranged so that one-half of its primary winding can be energized initially, and, subsequently, the remaining half can be energized, both halves then carrying equal current. (CMP 11) Informational Note: A hermetic refrigerant motor-compressor is not considered a standard part-winding start induction motor. Passenger Transportation Facilities. Any area open to the public associated with passenger transportation such as an airport, bus terminal, highway rest stop and service area, marina, seaport, ferry slip, subway station, train station, or port of entry. (CMP-18) Patient Bed Location. The location of a patient sleeping bed, or the bed or procedure table of a Category 1 space. [99:3.3.138] (CMP-15) Patient Care–Related Electrical Equipment. Electrical equipment appliance that is intended to be used for diagnostic, therapeutic, or monitoring purposes in a patient care vicinity. [99:3.3.139] (517) (CMP-15) Patient Care Space Category. Any space of a health care facility wherein patients are intended to be examined or treated. [99:3.3.140] (517) (CMP-15) Informational Note No. 1: The health care facility’s governing body designates patient care space in accordance with the type of patient care anticipated. Informational Note No. 2: Business offices, corridors, lounges, day rooms, dining rooms, or similar areas typically are not classified as patient care spaces. [99:A.‍3.3.140] ENHANCED CONTENT Collapse The word space conveys that the patient care area is often not defined by the four walls of a room. Formerly called patient care areas, patient care spaces are defined by four varying degrees of possible injury to a patient or caregiver (Categories 1–4) that an electrical system failure could cause. Category 1 poses the most risk to a patient or caregiver, and Category 4 provides the least amount of risk to the patient or caregiver. An operating room, where patients are subject to invasive procedures, is a Category 1 space. (Illustration from NFPA DiRECT®) Category 1 Space (Category 1). Space in which failure of equipment or a system is likely to cause major injury or death of patients, staff, or visitors. [99:3.3.140.1] (CMP-15) Informational Note: These spaces, formerly known as critical care rooms, are typically where patients are intended to be subjected to invasive procedures and connected to line-operated, patient care–related appliances. Examples include, but are not limited to, special care patient rooms used for critical care, intensive care, and special care treatment rooms such as angiography laboratories, cardiac catheterization laboratories, delivery rooms, operating rooms, post-anesthesia care units, trauma rooms, and other similar rooms. [99:A.‍3.3.140.1] Category 2 Space (Category 2). Space in which failure of equipment or a system is likely to cause minor injury to patients, staff, or visitors. [99:3.3.140.2] (CMP-15) Informational Note: These spaces were formerly known as general care rooms. Examples include, but are not limited to, inpatient bedrooms, dialysis rooms, in vitro fertilization rooms, procedural rooms, and similar rooms. [99:A.‍3.3.140.2] Category 3 Space (Category 3). Space in which the failure of equipment or a system is not likely to cause injury to patients, staff, or visitors but can cause discomfort. [99:3.3.140.3] (517) (CMP-15) Informational Note: These spaces, formerly known as basic care rooms, are typically where basic medical or dental care, treatment, or examinations are performed. Examples include, but are not limited to, examination or treatment rooms in clinics, medical and dental offices, nursing homes, and limited care facilities. [99:A.‍3.3.140.3] Category 4 Space (Category 4). Space in which failure of equipment or a system is not likely to have a physical impact on patient care. [99:3.3.140.4] (517) (CMP-15) Informational Note: These spaces were formerly known as support rooms. Examples of support spaces include, but are not limited to, anesthesia work rooms, sterile supply, laboratories, morgues, waiting rooms, utility rooms, and lounges. [99:A.‍3.3.140.4] Patient Care Vicinity. A space, within a location intended for the examination and treatment of patients, extending 1.8 m (6 ft) beyond the normal location of the bed, chair, table, treadmill, or other device that supports the patient during examination and treatment and extending vertically to 2.3 m (7 ft 6 in.) above the floor. [99:3.3.141] (517) (CMP-15) ENHANCED CONTENT Collapse The patient care vicin