Ch. 1 Definitions

service drop

"service drop" refers to the overhead conductors from the last pole connecting to the service entrance conductors of the building. See NEC 100 and 230, II

plenum

A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.

Luminaire

A complete lighting unit consisting of a light source such as a lamp or lamps, together with the parts designed to position the light source and connect it to the power supply. It may also include parts to protect the light source or the ballast or to distribute the light. A lampholder itself is not a luminaire.

Ground-Fault Circuit Interrupter (GFCI

A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.

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.

Intersystem Bonding Termination

A device that provides a means for connecting communications system(s) grounding conductor(s) and bonding conductor(s) at the service equipment or at the disconnecting means for buildings or structures supplied by a feeder or branch circuit.

Switch, Bypass Isolation

A manually operated device used in conjunction with a transfer switch to provide a means of directly connecting load conductors to a power source and of disconnecting the transfer switch.

separately derived system

A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.

Surge Arrester

A protective device for limiting surge voltages by discharging or bypassing surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions

Surge Protective Device (SPD).

A protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions and is designated as follows: Type 1: Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device. Type 2: Permanently connected SPDs intended for installation on the load side of the service disconnect overcurrent device, including SPDs located at the branch panel. Type 3: Point of utilization SPDs. Type 4: Component SPDs, including discrete components, as well as assemblies. FPN: For further information on Type 1, Type 2, Type 3, and Type 4 SPDs, see UL 1449, Standard for Surge Protective Devices.

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 or cutout box placed in or against a wall, partition, or other support; and accessible only from the front.

Switch, Isolating

A switch intended for isolating an electrical circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means.

Switch, General-Use

A switch intended for use in general distribution and branch circuits. It is rated in amperes, and it is capable of interrupting its rated current at its rated voltage.

Switch, Motor Circuit

A switch rated in horsepower that is capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.

Metal-Enclosed Power Switchgear

A switchgear assembly completely enclosed on all sides and top with sheet metal (except for ventilating openings and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with buses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided by doors, removable covers, or both. Metal-enclosed power switchgear is available in non-arc-resistant or arc-resistant constructions.

Ground-Fault Protection of Equipment

A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device. FPN No. 1: It is recognized that the equipment grounding conductor also performs bonding. FPN No. 2: See 250.118 for a list of acceptable equipment grounding conductors.

Ampacity

Amount of flowing current /amps that a conductor can carry and not exceed temperature rating. Per NEC 310.10

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. also includes low voltage light emiting diodes (LED)

Switch, Transfer.

An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another.

Interactive System

An electric power production system that is operating in parallel with and capable of delivering energy to an electric primary source supply system.

Raceway.

An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code

Handhole Enclosure

An enclosure for use in underground systems, provided with an open or closed bottom, and sized to allow personnel to reach into, but not enter, for the purpose of installing, operating, or maintaining equipment or wiring or both.

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. FPN: 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.

Hoistway

Any shaftway, hatchway, well hole, or other vertical opening or space in which an elevator or dumbwaiter is designed to operate. See Article 620

Show Window

Any window used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level.

Small appliances branch circuit

Circuit for supplying one or more outlets connecting appliances only. No permanent connect lighting. See 210.11 C 1 and 210.52 B

General purpose circuit

Circuits for which permanent lightning or appliance's may be connected.

Pressure connectors (solder less). Give example

Device that establishes a good electrical connection between two or more conductors by some means of mechanical pressure. A pressure connectors is used in place of soldering connections and is required to be of an approved type. Example:A wire nut is the most common connector of this type.

Circuit breaker

Device used to open or close non automatically but also to open a circuit automatically at a predetermined current overloading value. It may be thermally or mechanically operated. However ambient temperatures may affect the operation.

sealable equipment

Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made accessible without opening the enclosure. The equipment may or may not be operable without opening the enclosure.

Identified

Equipment is suitable for particular use or environment

Labeled

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.

Listed

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 either the equipment, material, or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.

Grounding Electrode.

Grounding Electrode. A conducting object through which a direct connection to earth is established.

Multi wire branch circuit

Has 2 or more ungrounded conductors with potential difference between them and also has a grounded neutral conductor with an equal potential difference between it and each of other conductors. See NEC 210.4

Premises Wiring (System).

Interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all their associated hardware, fittings, and wiring devices, both permanently and temporarily installed. This includes (a) wiring from the service point or power source to the outlets or (b) wiring from and including the power source to the outlets where there is no service point. Such wiring does not include wiring internal to appliances, luminaires, motors, controllers, motor control centers, and similar equipment.

Fitting

Mechanical Devices, such as locknut or bushing, intended for mechanical function (not electrical function).

Dead front

No live parts are exposed to persons

Non Current carrying conductors

One that carries current only in the event of a malfunction of equipment or wiring. An equipment ground conductor is a good example of this. It is used a protection but under normal conditions doesn't carrying current.

Qualified Person

One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.

Overload

Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated 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.

Service Conductors

Portion of the supply conductors that extend from the street main, duct or transformers to the service-entrance equipment of the premises supplied. for the overhead conductors, this includes the conductor from the last line pole (this does not mean the service pole) to the service equipment.

What does the term "Service" mean

Service means the conductors and equipment for delivering electrical energy from the secondary distribution system ... the street main, the distribution feeder, or the transformer ... to the wiring system on the premises. This includes the service - entrance equipment and the grounding electrode.

Conduit bodies.

Sperate part of conduit or tubing system that provides access through removable covers to the interior of the system. Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bodies. May also be called condulets. See 300.15 and article 314.16 (A)

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. FPN: 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

Neutral Conductor

The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. the neutral wire is current carrying and therefore will shock you.

service

The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served

Interrupting Rating

The highest current at rated voltage that a device is intended to interrupt under standard test conditions. FPN: Equipment intended to interrupt current at other than fault levels may have its interrupting rating implied in other ratings, such as horsepower or locked rotor current.

Short-Circuit Current Rating

The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.

Solar Photovoltaic System

The total components and subsystems that, in combination, convert solar energy into electric energy suitable for connection to a utilization load.

special permission

The written consent of the authority having jurisdiction.

Approved

UL listed and accepted

In Sight From (Within Sight From, Within Sight).

Where this Code specifies that one equipment shall be "in sight from," "within sight from," or "within sight of," and so forth, another equipment, the specified equipment is to be visible and not more than 15 m (50 ft) distant from the other.

Branch circuit

Wiring extending past last over current protection device. That does not thermal cutout or motor overload protection as the beginning of the branch circuit. Branch circuit begins at final fusing or circuit breaker point.

service cable

a service cable is a service donductor manufactured in the form of a cable and normally referred to as "SE cable"or "USE cable". See NEC 338

Ground

accidental or intentional electrical connection where electrical circuit or equipment is somehow connected to earth.

Explosion Proof apparatus

apparatus enclosed in a case that is capable of sustaining n explosion that may occur within itself and is also capable of preventing ignition of specified gases or vapors surrounding the enclosure by sparks, flames, etc. It must also operate at temperatures that will not cause ignition. If explosion does occur, the gases are allowed to escape either by the ground joints or threads, and the escaping gas cools down and stops the ignition of any external gases.

dwelling, multifamily

building contains three or more dwelling units

what does rain tight mean

capable of withstanding beating rain without resulting in entrance of water

Dust Tight

capacity to keep dust out of an enclosure so dust does not interfere with normal operations. see article 500 and 502 of NEC

enclosure

case or housing for apparatus to protect equipment from physical damage. See table 110.20 for enclosure types.

Feeder

circuit between service equipment and final branch circuit overcurrent device or devices. Feeders are typ large in size. They feed a feeder panel which have a lot of overcurrent devices within. See NEC 215.

Grounding Conductor

conductor used to connect equipment, devices, or wiring systems with grounding electrodes

Grounding Conductor (Equipment)

conductor used to connect non current carrying metal parts of equipment, raceways, and other enclosures to system grounding conductor at the service and/or the grounding electrode conductor.

Grounding Electrode Conductor

conductor used to connect the grounding electrode to the equipment grounding conductor and/or to the grounded conductor of the circuit at the service.

Copper Clad Aluminum conductors

conductors drawn from a copper clad aluminum rod with copper metallurically bonded to aluminum core. the copper forms a minimum of 10 percent of cross sectional area of solid conductor or each strand of stranded conductor.

System Bonding Jumper

connection between the grounded circuit conductor (usually the neutral) and the supply-side bonding jumper (SSBJ), or the equipment grounding conductor, or both, at separately derived systems.

What is Main Bonding Jumper

connection between the grounded circuit conductor and the equipment grounding conductor, at the service.

Equipment Bonding Jumper

connection between two or more portions of the equipment ground conductor.

receptacle

contact device installed at the outlet for the connection of a single attachment plug.

conductor, covered vs Conductor, Insulated

covered means encased with a material that is NOT reconized by this CODE as electrical insulation. Insulated... is reconized by this CODE as electrical insulation.

what is a general use switch

device intended for use as a switch in general distribution and branch circuits. it is rated in amperes and is capable of interrupting its rated current at its rated voltage.

what is meant by bonded or bonding

device or system is connected to establish electrical continuity or conductivity.

T rated switch

is an AC general use snap switch that is capable of use on resistive and inductive loads thatdo not exceed the ampere rating at the voltage involved, on tungsten-filament lighting loads that do not exceed the ampere rating at 120 volts, and on motor loads that do not exceed 80 percent of their ampere rating at the rated voltage.

Continuos Load

load where the max current is expspected to continue for 3 hours or more.

what is meant by "special permission"

mean written consent of the authority enforcing the NEC. this person is usually the electrical inspector.

what is meant by watertight

means a device is so constructed that moisture will not enter the enclosing case.

what is meant by waterproof

means device or system is so constructed or protected that exposure to the weather will not interfere with the successful operation. being watertight and rain tight may fulfill the requiremnts for weatherproof.

What does Rain Proof mean

means o constructed, protected, or treated as to prevent rain from interfereing with the successful operation of the apparatus.

service equipment

necessary equipment, usually consisting of fuses, breakers, switches...that are located near the entrance of the building, could be a whole room. used as the main control and means of cutoff for the supply.

Dwelling Unit

on or more rooms used by one or more persons, with space for sleeping, eating, and living, and a permanent provision forcooking and sanitation.

duty, intermediate

operate at 1 load and no load, or 2 loads and rest, or 3 loads, no load, rest

duty, continuous

operates at a constant load for an indefinite amount of time.

duty, varying

operation at loads, and for intervals of time, both of which may be subject to wide variations.

duty, short time

operation at substantially constant load for a short and definite, specified time.

outlet

point in wiring system at which current is taken to supply some equipment

Service entrance conductors (overhead systems)

portion of the service conductors between the terminals of service equipment and point outside the building, clear or building walls, where they are joined by a splice or tap to the service drop, street main, or other source of supply.

Demand factor.

ratio between max demand on a system or part of a system and the total connected load on the same system or part of system.

service lateral

refers to the underground service conductors between the stree main, including any risers at the pole or other structure or from the transformers and the first point of connection to the service entrance conductors in the terminal box. The point of connection is considered to be the point of entrance of the service conductors to the building.

Concealed

rendered inaccessible by the structure or finish of the building. Wire in concealed raceways are considered concealed, even though they may become accessible by withdrawling them.

service raceway

rigid metal conduit, electrical metal conduit (EMT), or other raceway that encloses service entrance conductors.

disconnecting mean

see article 240 for circuit breakers, article 422 space heating equipment art 424 for motors and controllers article 430 for air conditioning equipment.

Service entrance conductors (underground systems)

service conducors between terminal of service equipment and the point of connection to the service lateral. where the service equipment is located outside the building walls, there may be no service entrance conductors, or they may be entirely outside the building.

what are sets of service entrance conductors.

set of service entrance conductors tare taps run from main service conductors to service equipment.

enclosed

surrounded by case, housing, fense or wall that prevents persons from coming in contact with energized equipment.

Isolation switch

switch intended for isolating an electrical circuit from its source of power. it has no interrupting rating and is intended to be operated only after the circuit has been opened by some other means.

Motor Circuit Switch

switch, rated in HP, that is capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.

Grounded Connector

system or circuit conductor that is intentionally grounded.

what is meant by voltage of a circuit

the greatest effective difference of potential (root mean square difference that is) that exists between any 2 conductors of a circuit.

device

unit of electrical system that carries or controls electric energy as its principal function.