GENERAL PROVISIONS
§ 39.51. Definitions.
The following words and terms, when used in this subchapter, have the following meanings, unless the context clearly indicates otherwise:
Alive or live—Electrically connected to a source of potential differences or electrically charged so as to have a potential different from that of the earth. This term may be used in place of the term ‘‘current-carrying’’ where the intent is clear, to avoid repetitions of the longer term.
Apparent sag (at any point)—The departure of the wire at the particular point in the span from the straight line between the two points of support of the span, at 60°F with no wind loading.
Apparent sag of a span—The departure of the wire in a given span from the straight line between the two points of support of the span, at 60°F with no wind loading. If the two supports are at the same level this shall be the normal sag.
Authorized—Qualified.
Automatic—Self-acting, operating by its own mechanism when actuated by some impersonal influence, as for example, a change in current strength, not manual, without personal intervention. Remote control which requires personal intervention is not automatic, but manual.
Cable vault—Manhole.
Chief operator—The official in charge of safeguarding operations.
Circuit—A conductor or system of conductors through which an electric current is designed to flow, and connected equipment.
Climbing space—The vertical space reserve along the side of a pole structure to permit ready access for linemen to equipment and lines located on the pole structure.
Conductor—A metallic conducting material, usually in the form of a wire or cable, suitable for carrying an electric current, not including bus bars.
Conflicting—If applied to a pole line, this term shall mean a line so situated with respect to a second line, except at crossings, that the overturning of the first line will result in contact between its poles or conductors and the conductors of the second line, assuming that no conductors are broken in either line. Lines on opposite sides of a highway, street or alley are not considered as conflicting if separated by a distance not less than 60% of the height of the taller pole line, but in no case less than 20 feet.
Conduit—If used in reference to underground work, this term shall mean a group of any number of ducts for underground cables.
Current-carrying part—A part intended to be connected in an electric circuit to a source of voltage. Noncurrent-carrying parts are those not intended to be so connected.
Cutout—Any device, such as a fuse or circuit breaker, by which the electrical continuity of a conductor may be automatically broken by changes in current or voltage.
Dead—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. This term is used only with reference to current-carrying parts which are sometimes alive.
Disconnector—A switch intended to open a circuit only after the load has been thrown off by some other means. Manual switches designed for opening circuits are usually installed in circuit with disconnectors to provide a safe means for opening the circuit under load.
Duct—If used in reference to underground work, this term shall mean a single tubular runway for underground cables.
Electrical supply equipment—Equipment which produces, modifies, regulates, controls, or safeguards a supply of electrical energy. Similar equipment is excluded if used in connection with signaling systems when the voltage does not exceed 150 or when the voltage is between 150 and 400 and the power transmitted does not exceed three kilowatts.
Electrical supply lines—Those conductors and their necessary supporting or containing structures which are located entirely outside of buildings and are used for transmitting a supply of electrical energy. This shall not include open wiring on buildings in yards or similar locations where spans are less than 20 feet, and all the precautions required for stations or utilization equipment, as the case may be, are observed. Railway signal lines above 400 volts to ground are always supply lines within the meaning of this subchapter and those below 400 volts may be considered as supply lines, if so run and operated throughout.
Electrical supply station—Any building, room or separate space within which is located electrical supply equipment and which is generally accessible only to properly qualified persons. Included are generating stations and substations and generator, storage battery, and transformer rooms, but not manholes and isolated transformer vaults on private premises.
Enclosed—In locations where inflammable flyings, inflammable dust or explosives are present in dangerous quantities; an inclosure which will not admit accumulations of flying or dust, nor transmit sparks or flying particles to the accumulation outside.
Explosion-proof—In locations where the presence of inflammable gas makes the atmosphere explosive in character, an enclosure which will withstand, without injury and without transmitting flame to the outside, any explosion of gas which may occur in the enclosures.
Exposed—Able to be inadvertently touched or approached nearer than a safe distance by any person, as applied to objects not suitably guarded or isolated.
Grounded—Connected to earth or to some extended conducting body which serves instead of the earth, whether the connection is intentional or accidental.
Grounded system—A system having a permanent and effective electrical connection to earth. Such ground connection may be at one or more points. ‘‘Effective,’’ as used in this definition, means a connection to earth of sufficiently low resistance and high current-carrying capacity to prevent any current in the ground wire from causing a harmful voltage to exist between the grounded conductors and neighboring exposed conducting surfaces which are in good contact with the earth, or with neighboring surfaces of the earth itself, under the most severe conditions liable to arise in practice.
Guarded—Covered, shielded, fences, enclosed or otherwise protected by means of suitable covers or casings, barrier rails or screens, mats, or platforms, to remove the liability of dangerous contact or approach by persons or objects to a point of danger.
Handhole—An opening in an underground system into which workmen reach but do not enter.
Insulated—Separated from other conducting surfaces by a dielectric substance or air space permanently offering a high resistance to the passage of current, and to disruptive discharge through the substance or space, in suitable manner for the conditions to which it is subjected; otherwise within the purpose of these rules, it is uninsulated. Insulating covering of conductors is one means of making conductors insulated.
Insulating—If applied to the covering of a conductor or to clothing, guards, rods, and other safety devices, this term shall mean that a device, when interposed between a person and current-carrying parts, protects the person making use of it against electric shock from the current-carrying parts with which the device is intended to be used.
Isolated—Not readily accessible to persons unless special means for access are implemented.
Isolated by elevation—Elevated sufficiently so that persons may safely walk underneath.
Lateral conductor—A wire of cable extending in a general horizontal direction approximately at right angles to the general direction of the line conductors (in pole wiring work).
Lateral working space—The space reserved for working between conductor levels outside the climbing space, and to its right and left.
Line conductor—A wire or cable carrying electric current supported by poles, towers, or other structures, but not including vertical or lateral connecting wire.
Manhole or cable vault or splicing chamber—An opening in an underground system which workmen or others may enter for the purpose of installing cables, transformers, junction boxes, and other devices, and for making connections and tests.
Manual—Operated by personal intervention.
Normal sag—The difference in elevation between the highest point of support of a span and the lowest point of the conductor in such span, or in the curve of the conductor in the span produced, at 60°F with no wind loading.
Open lines—Overhead lines not in conduits, and consisting of single conductors or of individual twisted pairs, as opposed to multiple conductor cables.
Panelboard—A single panel containing busses, fuses and switches to control lights, fan motors and similar devices of small individual as well as aggregate capacity, placed in or against a wall or partition and accessible only from the front.
Permanently grounded—An effectively grounded connection to the earth, by use of an underground system of metallic pipe mains or other suitable means.
Pole face—That side of a pole on which crossarms are attached, or which is so designated by the utilities owning or operating the pole.
Qualified or authorized—Properly qualified or authorized to perform specified duties under the conditions existing. Responsibility for the authorization and decision as to the qualifications of employes rests with the employer or his agent.
Reconstruction—Replacement of any portion of an existing installation by new equipment or construction, not including ordinary maintenance replacements.
Rural districts—All places not urban, usually in the country, but in some cases within city limits.
Service—The connecting conductors by which a supply of electrical energy is carried from a supply line to the building or premises served.
Signal lines—Lines for public or private signal or communication service and devoted exclusively to the transmission of signals or intelligence, which operate at less than 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. Below 150 volts no limit is placed on the capacity of the system. Included are telephone, telegraph, messenger-call, clock, fire, or police alarm, and other systems conforming with these requirements. Lines used for signaling purposes, but not included under this definition, are considered as supply lines of the same voltage and shall so conform. Signal lines not for public use coming under this definition may be run and operated as supply lines if desired, and if constantly so run.
Splicing chamber—anhole.
Substantial—Constructed and arranged to be of adequate strength and durability for the service to be performed under the prevailing conditions.
Switch—A device for opening, closing or changing the connection of a circuit manually. In this subchapter, a switch shall be always considered manually operated, unless otherwise stated.
Switchboard—A large single panel or assembly of panels on which are mounted, partly on the face and partly on the back, switches, fuses, busses and usually instruments, and accessible both in front and in rear. Circuits and machinery of relatively large capacity are controlled from these boards.
Tags—Tags of distinctive appearance, indicating that the equipment or lines marked are being worked on.
Transformer vault—An isolated, fireproof enclosure, either above or below ground, in which transformers and the devices necessary for their operation are installed, and which is not continuously under attendance during operation.
Urban districts—Thickly settled communities, whether in cities or suburbs, where congested traffic often occurs. A highway, though in the country, on which the traffic is often very heavy, is considered urban.
Utilization equipment—Equipment, devices, and connected wiring, which utilize electrical energy for mechanical, chemical, heating, lighting, testing or similar purposes and are not a part of supply equipment, supply lines or signal lines.
Vertical conductor—A wire or cable extending in approximately vertical direction, in pole wiring work.
Voltage or volts—The highest effective voltage between the conductors of the circuit concerned, except that in grounded multiwire circuits not exceeding 750 volts between outer conductors it means the highest effective voltage between any wire of the circuit and the ground. In ungrounded low-voltage circuits ‘‘voltage to ground’’ means the voltage of the circuit. If one circuit is directly connected to another circuit of higher voltage as in the case of an autotransformer, both are considered to be of the higher voltage, unless the circuit of lower voltage is permanently grounded. Direct connection implies electrical connection as distinguished from connection merely through electromagnetic or electrostatic induction.
Wire gauges—The American Wire Gauge (A.W.G.), otherwise known as Brown & Sharpe (B. & S.) is the standard gauge for copper, aluminum, and other conductors, excepting steel, for which the Steel Wire Gauge (Stl. W. G.) is used throughout this Subchapter.
Cross References This section cited in 34 Pa. Code § 39.472 (relating to live electrical parts).
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