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from its web site at www.dir.ca.gov. These regulations are for the
convenience of the user and no representation or warranty is made that the information
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The following definitions of frequently used terms shall be accepted as the intended meanings of these terms whenever used in these High-Voltage Electrical Safety Orders (HVESO).
NOTE: Definitions of other terms used in only one article are included in the front of that article.
Accepted. An installation is “accepted” if it has been inspected and found by a nationally recognized testing laboratory to conform to specified plans or to procedures of applicable codes.
(A) Accessible (as applied to equipment). Admitting close approach because not guarded by locked doors (unless keys are readily available to those requiring access), elevation or other effective means. (See “Readily Accessible.”)
(B) Accessible (as applied to wiring methods). Not permanently closed in by the structure or finish of the building; capable of being removed or exposed without disturbing the building structure, finish, or fixed appurtenance thereto. (See “Concealed” and “Exposed.”)
(C) Readily Accessible. Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc.
(D) Safely Accessible. Not exposing persons installing, operating, maintaining, or inspecting electrical apparatus to serious risks of tripping or falling or of coming in contact with energized electrical parts, moving machinery, surfaces or objects operating at high temperatures, or other hazardous equipment.
Aerial Lift. A device used to raise workers to an elevated position.
Affected Employee. An employee whose job requires him or her to operate or use a machine or equipment on which cleaning, repairing, servicing, setting-up, or adjusting operations are being performed under lockout or tagout, or whose job requires the employee to work in an area in which such activities are being performed under lockout or tagout.
Ambient Temperature. The temperature of the cooling medium that comes in contact with the device or equipment.
Ampacity. The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Apparatus Case. The case (or tank) of electrical apparatus is that part which serves as the container for the principal energized parts and insulating medium.
Armored cable (Type AC). A fabricated assembly of insulated conductors in a flexible metallic enclosure.
Askarel. A generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. Under arcing conditions the gases produced, while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible gases depending upon the askarel type.
(See Environment, also.)
(A) Contaminated Atmosphere. An atmosphere containing contaminants which tend to impair the effectiveness of electrical insulation.
(B) Corrosive Atmosphere. An atmosphere containing contaminants which react chemically with the parts of an electrical installation so as to impair its electrical conductivity and/or its mechanical strength.
(C) Explosive Atmosphere. (See Article 34.)
(D) Flammable Atmosphere. (See Article 34.)
Authorized Employee or Person. For the purposes of Section 2940.13, a qualified person who locks out or tags out specific machines or equipment in order to perform cleaning, repairing, servicing, setting-up, and adjusting operations on that machine or equipment. An affected employee becomes an authorized employee when that employee's duties including performing cleaning, repairing, servicing, setting-up and adjusting operations covered under this section.
Authorized Person. A qualified person delegated to perform specific duties under the conditions existing.
Automatic. Self-acting, operating by its own mechanism when actuated by some impersonal influence, as, for example, a change in current strength, pressure, temperature, or mechanical configuration.
Automatic Circuit Recloser. A self-controlled device for automatically interrupting and reclosing an alternating current circuit, with a predetermined sequence of opening and reclosing followed by resetting, hold closed, or lockout operation.
Automatic Opening. (Tripping). The opening of a switching device under predetermined conditions without the intervention of an attendant.
AWG. American Wire Gauge.
Bare Conductor. See Conductor.
Barricade. Physical obstruction such as tapes, screens, cones, or structures setup in a manner intended to warn and limit access to a hazardous area.
Barrier. Physical obstruction which is intended to prevent contact with energized lines or equipment or prevents unauthorized access to a work area.
Basic Impulse Level (BIL). (See Ratings.)
Bond. An electrical connection from one metallic element to another for the purpose of minimizing potential differences and providing for mitigation of leakage current and electrolytic action.
Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path which will assure electrical continuity and the capacity to conduct safely any current likely to be imposed.
Bonding Jumper. A reliable conductor to assure the required electrical conductivity between metal parts required to be electrically connected.
Branch Circuit. That portion of a wiring system extending beyond the automatic overcurrent protective device, excluding any thermal cutout or motor running overload protective device that is not approved for short circuit duty.
Building. For the purposes of these Orders, a building is a structure which stands alone or which is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.
(A) Isolated Phase Bus. One in which each phase conductor is enclosed by an individual metal housing separated from adjacent conductor housings by an air space.
(B) Non-Segregated Phase Bus. One in which all phase conductors are in a common metal enclosure without barriers between phases.
(C) Segregated Phase Bus. One in which all phase conductors are in a common metal enclosure but are segregated by barriers between phases.
Bushing. An insulating structure including a through conductor, or providing a passageway for such a conductor, with provision for mounting on a barrier, conducting or otherwise, for the purpose of insulating the conductor from the barrier and conducting current from one side of the barrier to the other.
BWG. Birmingham Wire Gauge.
Cabinet. An enclosure designed either for surface or flush mounting, and provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.
Cablebus. An assembly of insulated conductors with fittings and conductor terminations in a completely enclosed, ventilated, protective metal housing.
Cable, Electrical. A stranded conductor (single-conductor cable) or a combination of conductors insulated from one another (multiple-conductor cable).
Cable Riser. (See Riser.)
Cable Sheath. A protective covering applied to cables.
NOTE: A cable sheath shall be permitted to consist of multiple layers of which one or more is conductive.
(A) Pothead. A device for the electrical and mechanical termination of an insulated electrical cable.
(B) Stress Cone. Cable termination which provides electrical stress relief for an insulated electrical cable.
(C) Terminal Chamber (Conduit Box). A separate compartment on electrical apparatus for terminating insulated electrical cables.
(D) Wiping Sleeve. A hollow, cylindrical, metal attachment to the tank (or case) or terminal chamber of electrical apparatus which is used for the mechanical termination of lead-sheathed insulated electrical cable.
Cable tray system. A unit or assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways. Cable tray systems include ladders, troughs, channels, solid bottom trays, and other similar structures.
Case (Tank). (See Apparatus Case.)
Certified. Equipment is “certified” if it bears a label, tag, or other record of certification that the equipment:
(A) Has been tested and found by a nationally recognized testing laboratory to meet nationally recognized standards or to be safe for use in a specified manner; or
(B) Is of a kind whose production is periodically inspected by a nationally recognized testing laboratory and is accepted by the laboratory as safe for its intended use.
Circuit. A conductor or system of conductors through which an electric current is intended to flow.
Circuit Breaker. (See Switching Devices.)
Clearance (Authorization). Authorization to enter an area and/or to perform an act restricted to authorized personnel.
Clearing Time. The time elapsing from the beginning of an overcurrent to the final circuit interruption.
Close and Hold. (See Ratings.)
Collector Ring. An assembly of slip rings for transferring electrical energy between a stationary and a rotating member.
Communication Lines. The conductors and their supporting or containing structures which are used for public or private signal or communication service, and which operate at potentials not exceeding 400 volts to ground or 750 volts between any two points of the circuit, and the transmitted power of which does not exceed 150 watts. When operating at less than 150 volts no limit is placed on the capacity of the system.
NOTE: Telephone, telegraph, railroad signal, data, clock, fire, police-alarm, community television antenna, and other systems conforming with the above are included. Lines used for signaling purposes, but not included under the above definition, are considered as supply lines of the same voltage and are to be so run.
Concealed. Rendered inaccessible by enclosures, raceways, structures, the finish of a building, etc.
Conductor. A wire, cable, or other conducting material suitable for carrying current.
(1) Bare. A conductor having no covering or electrical insulation whatsoever.
(2) Covered. A conductor encased within material of composition or thickness that is not recognized by these Safety Orders as electrical insulation.
(3) Insulated. A conductor encased within material of composition and thickness that is recognized by these Safety Orders as electrical insulation.
Construction. The erection of new wiring and equipment, and the alteration, conversion, and improvement of existing wiring and equipment.
Contactor. A device for repeatedly establishing and interrupting an electric power circuit.
Contaminated. (See Atmosphere.)
(A) Automatic Control. An arrangement of electrical controls that provides for switching or otherwise controlling or both in an automatic sequence and under predetermined conditions the necessary devices comprising an equipment. These devices thereupon maintain the required character of service and provide adequate protection against all usual operating emergencies.
(B) Manual Control. Control in which the main devices, whether manually or power operated, are controlled by an attendant.
(C) Manual Operation. Operation by hand without using any other source of power.
Controller. A device, or group of devices, which serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.
Corrosive. (See Atmosphere.)
Covered Conductor. See under “Conductor.”
(A) Asymmetrical Current. The combination of the symmetrical and the direct current component of the current.
(B) Available (Prospective) Short Circuit Current (at a given point in a circuit). The maximum current that the power system can deliver through a given circuit point to any negligible impedance short circuit applied at the given point, or at any other point that will cause the highest current to flow through the given point.
(C) Excitation (Magnetizing) Current. The current supplied to unloaded transformers or similar equipment.
(D) Minimum Operating Current (of a relay or fuse). The minimum current that will cause a device to complete its intended operation.
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.
(F) 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. (See Overcurrent.)
(G) Short-Time Current. (See Ratings.)
Current Carrying Part. A conducting part connected in an electric circuit to a source of voltage.
Cutout. (See Switching Devices.)
Cutout Box. An enclosure designed for surface mounting and having swinging doors or covers secured directly to and telescoping with the walls of the box proper. (See Cabinet.)
Damp Location. See “Environment.”
Dead. Free from any electrical connection to a source of potential difference and from electrical charges: Not having a potential difference from that of earth.
Dead-Front. Without live parts exposed to a person on the operating side of the equipment.
De-energized. Free from any electrical connection to a source of potential difference and from electrical charge; not having a potential different from that of the earth.
Designated Employee. A qualified person delegated to perform specific duties under the conditions existing.
Device. A unit of an electrical system that is intended to carry but not utilize electric energy.
Dielectric Heating. The heating of a nominally insulating material due to its own dielectric losses when the material is placed in a varying electric field.
Discharge Device. A device intended for the dissipation of the energy stored in a disconnected inductive or capacitive device.
Disconnect (Isolator). (See Switching Devices.)
Disconnected Position (of a switchgear assembly removable element). That position in which the primary and secondary disconnecting devices of the removable element are separated by a safe distance from the stationary element contacts.
Disconnecting Means. (See Switching Devices.)
Division. Unless otherwise designated in this subchapter, the phrase “division” refers to the current Division of Occupational Safety and Health or any of its predecessors including the former Division of Industrial Safety or the Division of Occupational Safety and Health Administration. Reference to the former Division of Industrial Safety or Division of Occupational Safety and Health Administration in these orders is meant to refer to their successor, the Division of Occupational Safety and Health, or any subsequent successor agency.
Drawout Mounted Device. One having disconnecting devices and in which the removable portion may be removed from the stationary portion without the necessity of unbolting connections or mounting supports.
Dust-Proof. So constructed or protected that dust will not interfere with its successful operation.
Dust-Tight. So constructed that dust will not enter the enclosing case.
(A) Continuous. A requirement of service that demands operation at a substantially constant load for an indefinitely long time.
(B) Intermittent. A requirement of service that demands operation for alternate intervals of (1) load and no load; or (2) load and rest; or (3) load, no load and rest.
(C) Periodic. A type of intermittent duty in which the load conditions are regularly recurrent.
(D) Short-Time. A requirement of service that demands operation at a substantially constant load for a short and definitely specified time.
(E) Varying. A requirement of service that demands operation at loads, and for intervals of time, both of which may be subject to wide variation.
Electric Line Truck. A truck used to transport workers, tools, and material, and to serve as a traveling workshop for electric power line construction and maintenance work. It is sometimes equipped with a boom and auxiliary equipment for setting poles, digging holes, and elevating material or workers.
Electric Supply Equipment. Equipment that produces, modifies, regulates, controls, or safeguards a supply of electric energy.
Electric Supply Lines. Those conductors used to transmit electric energy and their necessary supporting or containing structures. Signal lines of more than 400 volts to ground are always supply lines within the meaning of the rules, and those of less than 400 volts to ground may be considered as supply lines, if so run and operated throughout.
Electric Utility. An organization responsible for the installation, operation, or maintenance of an electric supply system.
Enclosed. Surrounded by a fence, wall, case, or housing which will prevent persons from accidentally contacting wiring, equipment, or energized parts contained therein.
Enclosed Space. A working space, such as a manhole, vault, tunnel, or shaft, that has a limited means of egress or entry, that is designed for periodic employee entry under normal operating conditions, and that, under normal conditions, does not contain a hazardous atmosphere, but may contain a hazardous atmosphere under abnormal conditions.
NOTE to the definition of “enclosed space”:
The Division of Occupational Safety and Health (Division) does not consider spaces that are enclosed but not designed for employee entry under normal operating conditions to be enclosed spaces for the purposes of this section. Similarly, the Division does not consider spaces that are enclosed and that are expected to contain a hazardous atmosphere to be enclosed spaces for the purposes of this section. Such spaces meet the definition of permit spaces in Section 5157 of the General Industry Safety Orders or Article 37 of the Construction Safety Orders.
Enclosure. The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts, or to protect the equipment from physical damage.
Energized Parts (Live Parts). Parts which are of a potential different from that of the earth, or some conducting body which serves in place of the earth.
Energy Isolating Device. A physical device that prevents the transmission or release of energy, including, but not limited to, the following: a manually operated electric circuit breaker, a disconnect switch, a manually operated switch, a slide gate, a slip blind, a line valve, blocks, and any similar device with a visible indication of the position of the device. (Push buttons, selector switches, and other control-circuit-type devices are not energy isolating devices.)
Energy Source. Any electrical, mechanical, hydraulic, pneumatic, chemical, nuclear, thermal, or other energy source that could cause injury to employees.
Entry (as used in Section 2943.1). The action by which a person passes through an opening into an enclosed space. Entry includes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space.
Environment. (See Atmosphere, also.)
(A) Damp Location. Partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
(B) Dry Location. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of some buildings under construction.
(C) Wet Location. Installations underground or in concrete slabs or masonry in direct contact with the earth, and locations subject to saturation with water or other liquids, such as vehicle washing areas, and locations exposed to weather and unprotected.
Equipment. A general term which includes material, fittings, devices, appliances, fixtures, apparatus, and the like, used as part of, or in connection with, an electrical installation.
Equipment Grounding Conductor. See “Grounding Conductor, Equipment.”
Explosion-Proof Apparatus. Apparatus enclosed in a case which is capable of withstanding an explosion of a specified gas or vapor which may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and which operates at such an external temperature that a surrounding flammable atmosphere will not be ignited thereby.
Exposed (as applied to energized parts). Energized parts that can be inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or insulated. (See Accessible and Concealed.)
Exposed (as applied to wiring methods). On or attached to the surface or behind panels designed to allow access. [See “Accessible (as applied to wiring methods).”]
Exposed (for the purposes of Article 41). Where the circuit is in such a position that in case of failure of supports or insulation, contact with another circuit may result.
Externally Operable. Capable of being operated without exposing the operator to contact with live parts.
Fall Protection. Any equipment, device, or system that prevents an employee from falling from an elevation or mitigates the effect of such a fall.
Fault. (See Current.)
Feeder. All circuit conductors between the service equipment, the source of a separate derived system, or other power supply source and the final branch-circuit overcurrent device.
Fitting. An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.
Fuse. An overcurrent protective device with a circuit opening fusible part that is heated and severed by the passage of overcurrent through it. (Note: A fuse comprises all the parts that form a unit capable of performing the prescribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit.)
(A) Expulsion Fuse Unit (Expulsion Fuse). A vented fuse unit in which the expulsion effect of gases produced by the arc and lining of the fuseholder, either alone or aided by a spring, extinguishes the arc.
(B) Power Fuse Unit. A vented, non-vented, or controlled vented fuse unit in which the arc is extinguished by being drawn through solid material, granular material, or liquid, either alone or aided by a spring.
1. Vented Power Fuse. A fuse with provision for the escape of arc gases, liquids, or solid particles to the surrounding atmosphere during circuit interruption.
2. Non-Vented Power Fuse. A fuse without intentional provision for the escape of arc gases, liquids, or solid particles to the atmosphere during circuit interruption.
3. Controlled Vented Power Fuse. A fuse with provision for controlling discharge during circuit interruption such that no solid material may be exhausted into the surrounding atmosphere. The discharge gases shall not ignite or damage insulation in the path of the discharge, nor shall these gases propagate a flashover to or between grounded members or conduction members in the path of the discharge when the distance between the vent and such insulation or conduction members conforms to manufacturer's recommendations.
Ground. A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and earth, or to some conducting body which serves in place of the earth.
(A) Ground (Reference). That conducting body, usually earth, to which electric potential is referenced.
Grounded. Connected to the earth or to some conducting body that serves in place of the earth.
Grounded Conductor. A system or circuit conductor which is intentionally grounded.
Grounded, Effectively. Intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or to persons.
Grounded, Impedance. Connected to ground through a connection in which an impedance has been inserted intentionally.
Grounded, Solidly. Grounded through a grounding connection in which no impedance has been inserted intentionally.
Grounded System, Impedance. A system which has one conductor or point (usually the mid-tap or neutral point of a transformer or generator windings) connected to the reference ground through an impedance.
Grounded System, Solidly. A system which has one conductor or point (usually the mid-tap or neutral point of a transformer or generator windings) connected to the reference ground with no intentional impedance imposed in the circuit.
Grounding Conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
Grounding Conductor, Equipment. The conductor used to connect noncurrent-carrying metal parts of equipment, raceways and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.
Grounding Connection (Ground Connection). (See Ground.)
Grounding Electrode (Ground Electrode). A conductor imbedded in the earth, used for maintaining ground potential on conductors connected to it, and for dissipating into the earth current conducted to it.
Grounding Electrode Conductor. The conductor used to connect the grounding electrode to the equipment grounding conductor, to the grounded conductor, or to both, of the circuits at the service equipment or at the source of a separately derived system.
Grounding Electrode Resistance. The resistance of the grounding electrode to earth.
Grounding Transformer. A transformer intended primarily for providing a neutral point for system grounding purposes.
Group Operation. The essentially simultaneous operation of all poles of a multi-pole switching device by one operating mechanism.
Guarded. Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach to a point of danger or contact by persons or objects.
Health care facilities. Buildings or portions of buildings in which medical, dental, psychiatric, nursing, obstetrical, or surgical care are provided.
NOTE: Health care facilities include, but are not limited to, hospitals, nursing homes, limited care facilities, clinics, medical and dental offices, and ambulatory care centers, whether permanent or movable.
Heating Equipment. For the purposes of Article 42, the term “heating equipment” includes any equipment used for heating purposes if heat is generated by induction or dielectric methods.
High-Power Tests. Tests in which the employer uses fault currents, load currents, magnetizing currents, and line dropping currents to test equipment, either at the equipment's rated voltage or at lower voltages.
High Voltage. A sustained voltage of more than 600 volts. (See Voltage.)
High-Voltage System. Associated electrical conductors and equipment operating at or intended to operate at a sustained voltage of more than 600 volts between conductors.
High-Voltage Tests. Tests in which the employer uses voltages of approximately 1,000 volts as a practical minimum and in which the voltage source has sufficient energy to cause injury.
Hook Stick. (See Switch Stick.)
Hot Tools and Ropes. Tools and ropes which are especially designed for work on energized high voltage lines and equipment. Insulated aerial equipment especially designed for work on energized high voltage lines and equipment shall be considered hot line.
Identified (as applied to equipment). Approved as suitable for the specific purpose, function, use, environment, or application, where described in a particular requirement.
NOTE: Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a nationally recognized testing laboratory (through listing and labeling), inspection agency, or other organization recognized under the definition of “acceptable.”
Indoor. Indoor, as an adjective, describes a device or equipment which, because of its construction, must be protected from the weather, or be installed in a location which is protected from the weather.
Induction Heating. The heating of a nominally conductive material due to its own I2R losses when the material is placed in a varying electromagnetic field.
Insulated. Separated from other conducting surfaces by a dielectric substance (including air space) offering a high resistance to the passage of current.
NOTE: When any object is said to be insulated, it is understood to be insulated in suitable manner for the conditions to which it is subjected. Otherwise, it is within the purpose of these orders, uninsulated. Insulating covering of conductors is one means of making the conductor insulated.
Insulated Conductor. See Conductor, Insulated.
Insulation (As applied to Cable). That which is relied upon to insulate the conductor from other conductors or conducting parts or from ground.
Interlock. An electrical, mechanical, or key-locked device intended to prevent an undesired sequence of operations.
Interrupter Switch. (See Switching Devices.)
Interrupting Rating. (See Ratings.)
Isolated (as applied to location). Not readily accessible to persons unless special means for access are used.
Isolated Power System. A system comprising an isolating transformer or its equivalent, a line isolation monitor, and its ungrounded circuit conductors.
Junction Box. (See Pull Box.)
Labeled. Equipment is “labeled” if there is attached to it a label, symbol, or other identifying mark of a nationally recognized testing laboratory:
(1) That makes periodic inspections of the production of such equipment, and
(2) Whose labeling indicates compliance with nationally recognized standards or tests to determine safe use in a specified manner.
Lanyard. A flexible line to secure a wearer of a safety belt or harness to a drop line, lifeline, or fixed anchorage.
Line Clearance Tree Trimming Operations. Operations which include the pruning, trimming, repairing, maintaining, chemical treatment, removal or clearing of trees, or cutting of brush and miscellaneous vegetation, that is within the vicinity of electric supply lines and equipment.
NOTE to the definition of “Line Clearance Tree Trimming Operations”: See Sections 2950 and 2951 for minimum approach distances related to line clearance tree trimming operations.
Linemen's Body Belt. A leather or web (cotton or nylon) belt designed specifically for employees working on poles or structures. It consists of a waist belt, generally cushioned, with a front buckle, two D rings for attaching safety straps and a multiple-looped strap for holding rings, snaphooks, holsters and other tool holding devices.
Listed. Equipment is “listed” if it is of a kind mentioned in a list that:
(1) Is published by a nationally recognized laboratory that makes periodic inspection of the production of such equipment, and
(2) States that such equipment meets nationally recognized standards or has been tested and found safe for use in a specified manner.
Live Parts. Energized conductive components.
Location. (See Environment.)
Magnetizing Current. (See Current - Excitation.)
Main Switch. (See Service Entrance Switch.)
Make and Latch (or Close and Hold) Rating. (See Ratings.)
Manhole. A chamber, in an underground system, containing working space large enough for a person to enter, which provides space and access for installation and maintenance of cables, transformers, or other equipment or apparatus.
Manhole Chimney. A vertical passageway for workers or equipment between the roof of the manhole and the surface (street) level.
Manual Control. (See Control.)
Manual Operation. (See Control.)
Maximum Voltage. (See Ratings.)
Medium Voltage Cable (Type MV). A single or multiconductor solid dielectric insulated cable rated 2001 volts or higher.
Metal-Clad Cable (Type MC). A factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape, or a smooth or corrugated metallic sheath.
Metal-Enclosed. Metal-enclosed, as an adjective, refers to electrical apparatus surrounded by a metal case or housing, usually grounded.
Minimum Approach Distance. The closest distance a qualified electrical worker and qualified line clearance tree trimmer may approach an exposed energized object.
Minimum Bending Radius. The minimum recommended radius to which a conduit or an insulated cable may be bent, measured from its inner surface.
Minimum Operating Current. (See Current.)
Multiple Fuse. An assembly of two or more single-pole fuses.
Nominal System Voltage. (See Voltage.)
Nonpropagating Liquid. A liquid which, when subjected to a source of ignition, may burn but the flame will not spread from the source of ignition.
Oil (Filled) Cutout. (See Switching Devices.)
Open Wiring. Uninsulated conductors or insulated conductors without grounded metallic sheaths or shields installed above ground, but not inside apparatus or wiring enclosures.
Outdoor. Outdoor, as an adjective, describes a device or equipment of weatherproof construction, or a location exposed to the weather.
Outlet. A point on the wiring system at which current is taken to supply utilization equipment.
Outline Lighting. An arrangement of incandescent lamps or electric discharge lighting to outline or call attention to certain features, such as the shape of a building or the decoration of a window.
Overcurrent. (See Current.)
Overload. (See Current.)
Overtemperature Protective Device. (See Thermal Protector.)
Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel; including buses, automatic overcurrent devices, and 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 or partition and accessible only from the front. (See “Switchboard.”)
Portable or Mobile Equipment. Electrical equipment mounted on skids, pads, legs, or vehicles, and capable of being moved to any required location.
Pothead. (See Cable Terminations.)
Power and Control Tray Cable (Type TC). A factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors under a nonmetallic sheath, approved for installation in cable trays, in raceways, or where supported by a messenger wire.
Power Fuse. (See Fuse.)
Power-Limited Tray Cable (Type PLTC). A factory assembly of two or more insulated conductors under a nonmetallic jacket.
Premises Wiring. (Premises wiring system.) The interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all of their associated hardware, fittings, and wiring devices, both permanently and temporarily installed, that extends from the service point of utility conductors or source of power (such as a battery, a solar photovoltaic system, or a generator, transformer, or converter) to the outlets. Such wiring does not include wiring internal to appliances, fixtures, motors, controllers, motor control centers, and similar equipment.
Protective Device. A device or combination of devices capable of detecting and automatically interrupting a specific condition.
Pull Box. A box with a blank cover into which workers may reach but not enter which is inserted in one or more runs of raceway to facilitate pulling, joining, supporting, or inspecting conductors. The term “pull box” includes but is not limited to: junction boxes, splice boxes, conductor support boxes, inspection boxes, and handholes.
Pulling Tension. The longitudinal force exerted on a cable during installation.
Qualified Electrical Worker. A qualified person who by reason of a minimum of two years of training and experience with high-voltage circuits and equipment and who has demonstrated by performance familiarity with the work to be performed and the hazards involved.
Qualified Line Clearance Tree Trimmer. A person who has completed a minimum of 18 months-related training and on-the-job experience and is familiar with the special techniques and hazards involved in line clearance tree trimming operations.
Qualified Line Clearance Tree Trimmer Trainee. Any worker regularly assigned to a line clearance tree trimming crew and undergoing on-the-job training who, in the course of such training, has demonstrated the ability to perform the assigned duties safely at that level of training.
Qualified Person (Qualified Employee). An employee (person) who by reason of experience or instruction is familiar with the operation to be performed and the hazards involved.
Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables or bus bars, with additional functions as permitted in this standard.
Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical metallic tubing, electrical nonmetallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
Rated. A designated value of an operating characteristic at which other characteristics are measured and specified.
(A) Basic Impulse Level (BIL). A reference impulse insulation strength expressed in terms of the crest value of the withstand voltage of a standard full impulse voltage wave.
(B) Interrupting Rating. Maximum interrupting capability under specified conditions, expressed in amperes or MVA.
(C) Make and Latch (Close and Hold) Rating. The highest RMS current at which the device or equipment is designed to operate.
(D) Short-Time Current Rating. The maximum RMS current a device, an assembly, or a bus is designed to carry for a specified short-time interval.
Readily Accessible. (See Accessible.)
Regulator Bypass Switch. (See Switching Devices.)
Release Free (Trip Free). A descriptive term indicating that the opening operation of a switching device can prevail over the closing operation during specified portions of the closing operation.
Remote-Control Circuit. Any electric circuit that controls any other circuit through a relay or an equivalent device.
Riser (Cable Riser). A vertical run of insulate cable, associated raceway, and termination.
Safely Accessible. (See Accessible.)
Safety Strap. A web strap designed specifically for use in conjunction with a linemen's body belt to secure the employee to a pole or structure in a manner that permits work with both hands.
Separately Derived System. A premises wiring system whose power is derived from a battery, a solar photovoltaic system, or from a generator, transformer, or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.
Service. The conductors and equipment for delivering energy from the electricity supply system to the wiring system of the premises served.
Service Cable. Service conductors made up in the form of a cable.
Service Conductors. That portion of the supply conductors which extends from the supply main, duct, or from transformers of the serving agency to the service equipment of the premises supplied. For overhead conductors this includes the conductors from the last line pole to the service equipment.
Service Entrance Conductors. The consumer-owned conductors extending between the service point and the service entrance equipment.
Service Entrance Switch (Main Switch). The disconnecting means and overcurrent protection installed at or near the service point.
Service Equipment. The necessary equipment, usually consisting of one or more circuit breakers or switches and fuses, and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and means of cutoff for the supply to a building or structure.
Service Factor. A multiplier which, applied to the rated output of an electric machine, indicates a permissible loading which may be carried continuously under the conditions for that service factor.
Service Point. The point of connection between the facilities of the serving agency and those of the premises wiring.
Shielded Cable. A cable in which the insulated conductor(s) is enclosed in a conducting envelope(s), so constructed that substantially every point on the surface of the insulation is at ground potential or at some predetermined potential with respect to ground.
Statistical Sparkover Voltage. A transient overvoltage level that produces a 97.72 percent probability of sparkover (that is, two standard deviations above the voltage at which there is a 50 percent probability of sparkover).
Statistical Withstand Voltage. A transient overvoltage level that produces a 0.14 percent probability of sparkover (that is, three standard deviations below the voltage at which there is a 50 percent probability of sparkover).
Stored-Energy Operation. Operation by means of energy stored in the mechanism, sufficient to complete a specified operation.
Stress Cone. (See Cable Terminations.)
Submersible. Submersible, as an adjective, describes a device which is so constructed that it will operate satisfactorily when completely or partially submerged in a liquid under specified conditions.
Suitable. Capable of performing with safety the particular function specified in these Orders.
Supervised. Under continuous or intermittent surveillance by a local or remote operator or automatic data processing system.
Switch (Hook) Stick. A device with an insulated handle and a hook or other means for performing stick operation of a switching device.
Switching Device. A manually operable device (unless otherwise stated in the HVESO) designed to close and/or open one or more electric circuits. Included in this category are circuit breakers, cutouts, disconnecting (or isolating) switches, disconnecting means, interrupter switches, and oil (filled) cutouts.
(A) Circuit Breaker. A device designed to open and close a circuit by non-automatic means, and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.
(B) Cutout. An assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as a disconnecting blade by the inclusion of a non-fusible member.
(C) Disconnecting Means. A device, or group of devices, or other means whereby the conductors of a circuit can be disconnected from their source of supply.
(D) Disconnecting (or Isolating) Switch (Disconnector, Isolator). A mechanical switching device used for isolating a circuit or equipment from a 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.
(E) Interrupter Switch. A switch, capable of making, carrying, and interrupting specified currents.
(F) Oil Cutout (Oil-Filled Cutout). A cutout in which all or part of the fuse support and its fuse link or disconnecting blades are mounted in oil with complete immersion of the contacts and the fusible portion of the conducting element (fuse link), so that arc interruption by severing of the fuse link or by opening of the contacts will occur under oil.
(G) Oil Switch. A switch having contacts which operate under oil (or askarel or other suitable liquid).
(H) Regulator Bypass Switch. A specific device or combination of devices designed to bypass a regulator.
System Operator. A qualified person designated to operate the system or its parts.
Tag. A system or method of identifying circuits, systems or equipment for the purpose of alerting persons that the circuit, system or equipment is being worked on.
Terminal Chamber. (See Cable Terminations.)
Test Position (of a switchgear assembly). That position in which the primary disconnecting devices of the removable element are separated by a safe distance from those in the housing and the secondary disconnecting devices are in operating contact.
Thermal Protector -General. An inherent protective device which is responsive to temperature or current, or both, and which, when properly applied, protects the equipment against overheating due to overload or failure to start.
Transformer Bank. A transformer installation consisting of two or more transformers.
Transformer Installation. An electrical installation consisting of one or more transformers, including associated lead wires and interconnections, which transforms electric energy from one or more alternating current circuits to one or more other alternating current circuits.
Transformer Primary Winding. The winding on the energy input (source) side.
Transformer Secondary Winding. The winding on the energy output (load) side.
Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
Vault. A room, above or below ground (including manholes) of fire-resistant construction, primarily used for installing, operating, or maintaining electrical equipment or cable.
Vented Vault. A vault that has provision for air changes using exhaust flue stacks (vault vents) and low-level air intakes operating on pressure and temperature differentials that provide for airflow that precludes a hazardous atmosphere from developing.
Ventilated. Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors.
(A) Maximum Voltage. (See Ratings.)
(B) Nominal Voltage. A nominal value assigned to designate a system of a given voltage class.
(C) Voltage (of a circuit). The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned.
NOTE On various systems such as 3-phase, 4-wire, single phase 3-wire and 3-wire direct current, there may be various circuits of various voltages.
(D) Voltage to Ground. In grounded circuits the voltage between the given conductor and that point or conductor of the circuit which is grounded; in ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
Weatherproof. So constructed or protected that exposure to the weather will not interfere with successful operation.
Work-Positioning Device System. A body belt or body harness system rigged to allow an employee to be supported on an elevated surface, such as a utility pole, tower leg, or wall, and work with both hands free while leaning.
1. New Group 2 (Articles 50 through 86, Sections 2700 through 2949) filed 7-27-73; effective thirtieth day thereafter (Register 73, No. 30). Approved by State Building Standards Commission 2-23-73.
2. Amendment and deletion of numbers preceding definitions of subsection (b) filed 10-14-75 as an emergency; effective upon filing (Register 75, No. 42). Issuing Agency: Occupational Safety and Health Standards Board.
3. Certificate of Compliance filed 1-9-76 (Register 76, No. 2).
4. Amendment of subsection (b) filed 7-6-79 as procedural and organizational; effective upon filing (Register 79, No. 27).
5. Amendment of subsection (b) filed 8-9-79; effective thirtieth day thereafter (Register 79, No. 32).
6. Amendment of subsection (b) filed 10-29-80; effective thirtieth day thereafter (Register 80, No. 44).