Subchapter B. ELECTRIC SAFETY

§ 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.

 Any person who violates this subchapter or any regulations of the Department or who interferes with the Department or its duly authorized representative in the enforcement of these provisions or regulations will be deemed guilty of a misdemeanor and may, upon conviction thereof, be punished by fine or imprisonment, or both under act of April 27, 1927 (P. L. 465, No. 299) (35 P. S. § §  1221—1235.1).

METHODS OF PROTECTIVE GROUNDING

§ 39.61. Applicability.

 The provisions of § §  39.61—39.70 (relating to methods of protective grounding) apply to all installations within this Commonwealth, whether existing, new, reconstructions, extensions, or the like except as modified or waived as provided in §  39.63 (relating to modification or waiver of provisions).

 The provisions of § §  39.61—39.70 (relating to methods of protective grounding) are specifically directed to all lightning arrester grounding and to the grounding of all circuits, equipment, or wire runways when the grounding is intended to be a permanent and effective protective measure. Such provisions do not require that grounding be done, but cover the methods for protective grounding. The rules requiring groundings are included under parts one, three, and four of the National Electrical Safety Code. Such provisions do not apply to the grounding of arresters on signal circuits, to the grounded return of trolley or third rail systems, nor to the grounding of lightning protection wires if these are not connected to electrical circuits or equipment.

 The provisions of §  39.61—39.70 (relating to methods of protective grounding) may be modified or waived by the proper administrative authority or its authorized agents in the following instances:

   (1)  If application of provisions involve expense not justified by the protection secured, or for any other reason where application of provisions is shown to be impracticable.

   (2)  If equivalent or safer construction may be more readily provided by other means.

   (3)  In certain instances where temporary installations or installations are shortly to be dismantled or reconstructed.

   (4)  In cases of emergency or pending decision of the administrator the person responsible for the installation may decide as to modification or waiver of any rule, subject to review by proper authority.

   (5)  If other methods of construction and installation than those specified in this chapter are used as experiments to obtain information, if done where the supervision may be given by the proper administrative authority.

 The time allowed for bringing existing installations into compliance with the rules shall be determined by the proper administrative authority.

 (a)  Material and continuity. The ground conductor shall be of copper or of other metal which will not corrode excessively under the existing conditions and, if practicable, shall be continuous. Joints shall be made and maintained so as to conform to the resistance and current-carrying capacity requirements of §  39.69 (relating to ground resistance). Ground connections from circuits should not be made to jointed piping within buildings, except that water piping outside of meters and beyond any point which is liable to disconnection, may be used. Reference should also be made to §  39.68 (relating to methods of ground connection). No automatic cutout shall be inserted in the ground conductor or connection except in a ground connection from equipment where its operation will immediately result in the automatic disconnection from all sources or energy of the equipment so grounded; no switch shall be so inserted except in plain sight, provided with distinctive marking and effectively isolated from unqualified persons. Reference should also be made to §  39.67 (relating to attachment of ground conductor).

 (b)  Size and number. The size and number of ground conductors shall be as follows:

   (1)  For grounding circuits the ground conductors shall have a combined cross section and current capacity sufficient to insure the continuity of the ground connection and its continued compliance with §  39.69, under conditions of excess current caused by accidental grounding of any normally ungrounded conductor of the circuit. No individual ground conductor for electrical circuits shall have less current capacity than that of a No. 6 copper wire, except that for additional grounds after the first on any circuit, smaller ground wires may be used, provided that they are in no case smaller than the conductor to which they are attached nor smaller than No. 10 copper.

   (2)  For lightning arrester ground connections the ground conductor or conductors shall have a current carrying capacity sufficient to insure continuity of the ground connection under conditions of excess current caused by or following discharge of the arrester. No individual ground conductor shall be smaller than a No. 6 wire.

   (3)  Electrical equipment shall conform to the following:

     (i)   For electrical equipment the current-carrying capacity of a ground conductor shall be not less than that provided by a copper wire of the size indicated in the following table:

     (ii)   If there is no cutout protecting the equipment, the size of ground conductor shall be determined by the design and operating conditions of the circuit.

     (iii)   In the portable cord to portable equipment protected by fuses not greater than 10-ampere capacity, a No. 18 ground wire may be used.

 (c)  Mechanical protection and guarding against contact. Mechanical protection and guarding against contact shall be provided as follows:

   (1)  If exposed to possible mechanical injury the ground conductor shall be protected by substantial conduit or other guard.

   (2)  Guards for the ground conductors of the lightning arresters should be of nonmagnetic material unless the ground conductor is electrically connected to both ends of the guard.

   (3)  If resistance of the ground connection is in excess of the values in §  39.69, for water pipe grounds, the ground conductor, except in rural districts, shall be protected and guarded by being enclosed in insulating conduit or molding to protect persons from injury by coming into contact with it. A high resistance may exist where artificial grounds are necessarily permitted in lieu of the preferable grounds to buried metallic water piping systems.

   (4)  Mechanical protection and insulating guards should extend for a distance of not less than 8 feet above any ground, platform, or floor from which ground conductors are accessible to the public, however, the following precautions are recommended:

     (i)   Insulating mechanical protection is advisable for single arrester grounds, even when the connection is made to a water piping system, and has therefore a low resistance, since a single connection is liable to be accidentally broken.

     (ii)   Even where ground connections have a resistance not exceeding that specified in §  39.69, and no guard is therefore provided, or, as an additional protection to persons even where guards are used artificial grounds may be arranged to minimize the potential gradient along the surface of the earth by use of radial connecting wires underneath the earth surface or by other suitable means.

   (5)  A circuit ground conductor shall be guarded as required for current-carrying conductors of the circuit, unless the ground conductor is entirely outside buildings, has strength and current capacity not less than that of No. 6 copper wire, and the circuit is elsewhere grounded by other ground conductors, except that in stations substantial bare ground busses may be used.

 (d)  Underground conductors. Wires used for ground conductors, if laid underground shall, unless otherwise mechanically protected, be laid slack to prevent their being readily broken, and shall have joints carefully painted or othewise protected against corrosion.

 (a)  Permanence. The ground connections shall be permanent and effective and made as indicated in subsection (b), if possible, or else as prescribed in subsection (c), (d) or (e). Reference should also be made to §  39.69 (relating to ground resistance).

 (b)  Piping system. For circuits, equipment, and arresters at supply stations, connections shall be made to all available active continuous metallic underground water piping systems between which no appreciable difference of potential normally exists, and to one such system if appreciable differences of potential do exist between them. At other places connections shall be made to at least one such system, if available. Gas piping shall not be used. References should be made to § §  39.65 and 39.68 (relating to ground conductor; methods of ground connection). The term ‘‘available,’’ as used in this rule, shall mean ordinarily within 500 feet for stations. The protective grounding of electrical circuits and equipment to water pipe systems in accordance with this Subchapter shall always be permitted, since such grounding offers the most efficient protection to life and property and is not injurious to the piping systems.

 (c)  Alternate methods. If underground metallic piping systems are not available, other methods which will secure the desired permanence and conductance may be permitted. Where available, metal well casings, local metal drain pipes, and similar buried metal structures of considerable extent may be used in lieu of extended buried water-piping systems. Ground connection may be made to the steel frame of a building containing the grounded circuits or equipment, to which frames of machines and other noncurrent-carrying surfaces should also then be connected. In such cases the building frame shall be itself well grounded by effective connection to the ground which may require artificial grounding for steel frame buildings supported on masonry or unreinforced concrete footings.

 (d)  Artificial grounds. If resort to artificial grounds is necessary, their number shall be determined by the following requirements:

   (1)  No more than one artificial ground is required for lightning arresters, except for large current capacity. At least two grounds are required for low voltage alternating current distribution circuits at transformers or elsewhere.

   (2)  If no part of the circuit or equipment protected may be reached by persons while they are standing on the ground or damp floors, or by persons while touching any metallic piping to which the ground wire is not effectively connected, a single artificial ground may be used even if its resistance exceeds that specified in §  39.69. In such cases guards should be provided for the ground conductor in accordance with §  39.65(c) wherever it is otherwise accessible, or to provide insulating mats or platforms so located that persons cannot readily touch the ground conductor without standing on such mats or platforms.

 (e)  Grounds to railway returns. Protective ground connections shall not be made to railway negative return circuits when other effective means of grounding are available, except ground connections from electric railway lightning arresters. When ground connections are necessarily made to the grounded track return of electric railways, they shall be made in such a manner as not to afford a metallic connection between the railway return and other grounded conducting bodies. This provision shall not prohibit the making of drainage connections which are not protective grounds between piping systems and railway negative return circuits for the prevention of electrolysis. Multiple protective ground connections from other circuits to railway returns shall be avoided, and if multiple artificial grounds are made on such other circuits near such railway returns, they shall be so arranged as to prevent the flow of any considerable current in and between such connections, thus reducing their effectiveness, or causing other damage.

 (a)  Direct current distributing systems. The neutral of three-wire direct current systems shall be grounded at one or more supply stations, but not at individual services nor within buildings served. One side of a two-wire direct current system may be grounded, but at one station only. In three-wire systems the neutrals entering any junction box should be bonded together, but the box should not be specially grounded. In two-wire systems the grounded side of the circuit should be insulated from ground except at the station ground connection.

 (b)  Alternating current distribution systems. All secondary distribution systems shall be grounded at the building services or near the transformer (or transformers) either by direct ground connection or by the use of a system ground wire to which are connected the grounded conductors of many secondary mains and which is itself effectually grounded at intervals which fulfill, for any secondary utilizing the system ground wire, the resistance and current carrying requirements of §  39.69 (relating to ground resistance). Single-phase, three-wire distribution systems shall be grounded at the neutral conductor. Two-wire, single-phase systems shall be grounded at the neutral point or on either conductor. Two-wire, single-phase and two or three phase systems shall, in general, be grounded at that point of the system which brings about the lowest voltage from ground of unguarded current carrying parts of connected devices and also permits most convenient grounding. If one phase of a two or three phase system is used for lighting, that phase should be grounded and at the neutral conductor, if one is used. In the absence of direct grounds at all building services, ground connections shall be made to the grounded neutral or other grounded conductor of a secondary system supplying more than one utilization equipment, at intervals that will fulfill the resistance and current-carrying requirements of §  39.69. If the secondaries of transformers are supplying a common set of mains, the fuses shall be installed only at such points as will not cause the loss of the ground connections after the fuses in the transformer circuits or mains have been blown. Multiple grounds are preferable in all cases, because of the assurance provided against loss of the protection afforded by the chance disconnection of any ground connection. Grounds other than the single ground connection at the building service shall not be made to alternating current secondaries within buildings. Reference should be made to §  39.66 (relating to nature of ground connection).

 (c)  Lightning arresters. The connection to a lightning arrester shall be at such a point that its ground conductor is as short and straight as practicable. Ground conductors for lightning arresters shall not pass through iron or steel conduits unless electrically connected to both ends of such conduits.

 (d)  Equipment and wire runways. The point at which the ground conductor is attached to equipment or wire runways shall, if practicable, be readily accessible.

 (a)  Ground connections to metallic piping systems shall be made on the street side of water meters, which might interrupt the continuity of the underground metallic pipe systems, unless otherwise provided in subsection (b), but connections may be made immediately inside building walls to secure accessibility for inspection and test. When water meters are located outside buildings or in concrete pits within buildings where piping connections are inbedded in concrete flooring, the ground connection may be made on the building side of the meters, if they are suitably shunted.

 (b)  When the making of a ground to a piping system outside the meter or other device would involve a long run, connection for equipment or wire runways, not for circuits, may be made to the water piping system at a point near the part to be protected, if there are no insulating joints in the pipe to prevent a good ground. In such cases care shall be taken to electrically connect all parts of the piping system liable to create a hazard, if they become alive, to shunt the pipe system where necessary around meters, and so forth, in order to keep the connection with the underground piping system continuous. Gas piping systems within buildings shall not be used for purposes of this rule, except that gas piping need not be insulated from otherwise well-grounded electrical fixtures and if the making of another ground connection for a fixture would involve a long run and the fixture is, therefore, not within reach of plumbing or plumbing fixtures, the gas piping may for small fixtures be utilized as the sole ground connection. If so used the gas piping and water piping systems within the building shall be grounded at their points of entrance. Reference should also be made to § §  39.65 and 39.66 (relating to ground conductor; and nature of ground connection).

 (c)  The ground connection to metallic piping systems shall be made by sweating the ground wire into a lug attached to an approved clamp and firmly bolting the clamp to the pipe, after all rust and scale have been removed, or by soldering the ground connection into a brass plug which has been tightly screwed into a pipe fitting or, where the pipe is of sufficient thickness, screwed into a hole in the pipe itself, or connection may be made by other equivalent means. The point of connection shall be as readily accessible as possible, and the position should be recorded. With bell and spigot joint pipe it may be necessary to connect to several lengths where circuits or equipment of large current-carrying capacity are being grounded.

 (d)  Artificial grounds shall be located, where practicable, below permanent moisture level, or failing this at least 6 feet deep. Each ground should present not less than 2 square feet surface to exterior soil. Areas where ground water level is close to the surface shall be used when available.

 (a)  Limits. It is recommended that the combined resistance of the ground wires and connections of any grounded circuit, equipment or lightning arrester should not exceed the values given below, if grounded connections made according to §  39.66 (relating to nature of ground connection) will sufficiently limit the resistance. It will frequently be impracticable with artificial grounds to obtain resistances in dry or other high resistance soils as low as the values given below for ordinary soils. In such cases two grounds shall be used as defined in §  39.68 (relating to methods of ground connection), and no requirement shall be made as to resistance. Reference should also be made to §  39.66. The current stated opposite the different resistances in the table is either the current capacity of a circuit from which leakage may occur to the ground circuit, or the continuous current capacity to which the grounded equipment or arrester is limited by design or by automatic cutouts. If the secondary is exposed only through transformer windings, this current capacity shall be that of the primary fuse of the transformer. If the secondary is exposed by the conductors of conflicting or crossing high voltage circuits, the current capacities shall be those of the automatic cutouts in such circuits. The product of the corresponding numbers in the first and second columns shall never be greater than 150, that is, the potential difference due to the stated current is never greater than 150 volts, if connections are made to water pipes. If more than one ground is made on the same circuit, equipment or arrester, in the same vicinity, all such grounds shall be considered collectively in respect to meeting the requirements of this section:

 (b)  Checking. The resistance of station grounds shall be checked when made. With artificial grounds this check may be made by measuring the voltage between the grounded point of the circuit, or the grounded frame of the equipment or the grounded point of the lightning arrester and an auxiliary metal reference rod or pipe driven into the ground, while a measured current is flowing through the ground connection and any exposed metal piping or other artificial ground in the vicinity, but not within 20 feet. If the station ground is to water piping, the check may be made with current flowing through the water piping and some independent piping system or artificial ground in the vicinity, but not within 20 feet. The auxiliary road or pipe shall be at least ten feet from any artificial ground or piping systems through which the measured current is made to flow. All ground connections shall be inspected periodically. Ground connections on distribution circuits shall, when installed, be tested for resistance unless multiple grounding to water piping systems is used.

 (a)  Ground conductors. Ground conductors shall be run separately to the ground or to a sufficiently heavy grounding bus or system ground cable which is well connected to ground at more than one plate from equipment and circuits of each of the following classes:

   (1)  Lightning arresters.

   (2)  Secondaries connected to low voltage lighting or power circuits.

   (3)  Secondaries of current and potential transformers and cases of instruments on these secondaries.

   (4)  Frames of direct current railway equipment and of equipment operating in excess of 750 volts.

   (5)  Frames of utilization equipment or wire runways other than covered by paragraph (4).

 (b)  Grounds. Lightning arrester ground connections shall not be made to the same artificial ground such as driven pipes or buried plates as circuits or equipment, but should be well spaced and, where practicable, at least 20 feet from other artificial grounds.

   This section cited in 34 Pa. Code §  39.61 (relating to applicability); 34 Pa. Code §  39.62 (relating to scope); 34 Pa. Code §  39.63 (relating to modifications or waiver of provisions); 34 Pa. Code §  39.66 (relating to nature of ground connection); 34 Pa. Code §  39.103 (relating to protective grounding); 34 Pa. Code §  39.183 (relating to ground wires); 34 Pa. Code §  39.197 (relating to grounding); 34 Pa. Code §  39.219 (relating to grounding or isolating service conduits); 34 Pa. Code §  39.292 (relating to grounding noncurrent-carrying parts); and 34 Pa. Code §  39.304 (relating to grounding of arresters for signaling systems).

INSTALLATION AND MAINTENANCE OF ELECTRICAL SUPPLY
STATION AND EQUIPMENT

§ 39.81. Applicability.

 This section and § §  39.82—39.90 apply to installations within this Commonwealth, whether existing, new, reconstructions, extensions, or the like, except as waived or modified by §  39.83 (relating to modification or waiver of provisions).

 This section and § §  39.81 and 39.83—39.90 are specificially directed to electrical equipment of indoor and outdoor stations and substations, and to similar equipment, including generators, motors, storage batteries, transformers, and lightning arresters, when installed in factories, mercantile establishments, vehicles, or elsewhere, if the equipment is in separate rooms or enclosures, under control of properly qualified persons, if the interiors of such rooms or enclosures are accessible only to such persons.

 This section and § §  39.81, 39.82 and 39.84—39.90 may be modified or waived by the proper administrative authority or its authorized agents and shall be so modified or waived in the following instances:

   (1)  Application of the provisions involve expense not justified by the protection secured, or for any other reason if application of provisions is shown to be impracticable.

   (2)  If equivalent or safer construction can be more readily provided by other means.

   (3)  In certain instances where temporary installations or installations are shortly to be dismantled or reconstructed.

   (4)  In cases of emergency or pending decision of the administrator, the person responsible for the installation may decide as to modifications or waiver of any rule, subject to review by proper authority.

 Time allowed for bringing existing installations into compliance with the rules will be determined by the proper administrative authority.

 Rooms or spaces in which electrical supply equipment is installed shall comply with the following requirements:

   (1)  No room or space in which electrical supply equipment is installed shall be used for the storage of material or for manufacturing processes causing hazard to electrical operators, except those materials or processes attendant upon the production or distribution of a supply of electrical energy.

   (2)  They shall be free from flyings and inflammable gas, except for battery rooms. Reference should be made to § §  39.121—39.127 (relating to storage batteries). Indoor stations should be dry and well ventilated.

   (3)  In outdoor stations or stations in wet tunnels or subways live parts of equipment shall be enclosed in weatherproof cases, unless the equipment is suitably designed to withstand the prevailing atmospheric conditions and the live parts are suitably guarded against contacts, or isolated by elevation. Ungrounded conductors not in conduit shall be on suitable insulators, properly guarded or isolated by elevation.

 (a)  Rooms and spaces shall have good artificial illumination. Arrangement of permanent fixtures and plug receptacles shall be such that portable cords need not be brought into dangerous proximity to live electrical apparatus. Lamps shall be arranged to be controlled, replaced, or trimmed from readily accessible places.

 (b)  A separate emergency source of illumination from an independent generator, storage battery, gas main, lanterns or other suitable source shall be provided in every station where an attendant is located.

 (a)  Rooms and spaces shall be arranged with fences, screens, partitions, or walls, so as to prevent entrance of unauthorized persons or interference by them with equipment inside, and entrances not under observation of an authorized attendant shall be kept locked. Signs prohibiting entrance to unauthorized persons shall be displayed at entrances.

 (b)  Above all equipment, substantial roofs or ceilings shall be provided, except above equipment placed outdoors, if such portions of the equipment as would be injured by rains or by flying or falling objects are suitably enclosed or guarded to prevent such damage.

 (a)  Floors shall have even surfaces and afford secure footing. Projecting nails, loose boards, uneven or greasy wood floors, and smooth iron floors shall be avoided.

 (b)  Passageways, stairways, and working spaces shall be unobstructed, and shall, if possible, provide at least 6.5 feet of headroom unless they are used solely for infrequent inspection, construction and repair. Reference should also be made to §  39.104 (relating to working space about electrical equipment).

 (c)  Floor openings over 2 feet deep, and stairways or raised platforms over 4 feet high shall be provided with suitable handrails. Except for loading platforms, such rails are recommended if height exceeds 2 feet, especially where they are adjacent to live or moving parts, or the working space on the platform is restricted.

 (d)  Floor openings over 6 feet deep, and the edges of all raised platforms over 6 feet high, shall, if possible, be provided with suitable toeboards.

 (e)  Toeboards shall, if possible, be arranged at back of stairway treads if they are over exposed live or moving parts or over working spaces, passageways or other stairways.

 (a)  Each room or space and each working space about equipment shall have suitable means of exit which shall be kept clear of obstructions.

 (b)  If the plan of the room or space and the character and arrangement of equipment are such that an accident would be liable to prevent an employe from getting out of the room through a single exit, as in the case of long narrow rooms, platforms or passageways, a second exit shall, if practicable, be provided.

 Each room or space where an operator is in attendance shall be provided with adequate approved fire-extinguishing appliances conveniently located and conspicuously marked. Any such appliances which have not been approved by Underwriters’ Laboratories for use on live parts should be plainly and conspicuously marked with a warning to that effect whenever placed in rooms containing exposed live parts over 300 volts to ground.

   This section cited in 34 Pa. Code §  39.81 (relating to applicability); 34 Pa. Code §  39.82 (relating to scope); 34 Pa. Code §  39.83 (relating to modification or waiver of provisions); and 34 Pa. Code §  39.192 (relating to scope).

PROTECTIVE ARRANGEMENTS OF EQUIPMENT

§ 39.101. General requirement.

 (a)  Electrical supply equipment shall comply with this Subchapter when placed in service, and shall thereafter be periodically cleaned and inspected. Defective equipment shall be put in good order or permanently disconnected. Defective wiring, when hazardous, shall be repaired or removed.

 (a)  Grounding method. Lightning arresters, grounding, and all grounding of circuits, equipment or wire runways, intended to be a permanent and effective protective measure, shall be made in accordance with methods specified in § §  39.61—39.70 (relating to methods of protective grounding).

 (b)  Grounding noncurrent-carrying metal parts. Electrical supply equipment, if operating at over 150 volts to ground, or if in hazardous locations, shall have their exposed noncurrent carrying metal parts, such as frames of generators, motors, and switchboards, and cases of transformers and oil switches, permanently grounded. References should also be made to § §  39.115 and 39.159 (relating to grounding noncurrent-carrying parts; grounding noncurrent-carrying metal parts). When regulating voltage, generators or converters supplying circuits not exceeding 140 volts to ground are operated at not more than 180 volts, such generators or converters are considered not to exceed 150 volts to ground. Hazardous locations include those where dampness, acid fumes, explosives, inflammable gas, or flyings normally exist.

 (c)  Exemptions. Exposed noncurrent-carrying metal parts of electrical supply equipment operating on grounded direct current circuits or on series direct-current circuits may be left ungrounded if no inflammable gas is present, and if suitable insulating floors, platforms, or mats are used, so that no person may inadvertently come in contact with such ungrounded parts while he is standing upon any grounded surface, including floors not of insulating material; and further if suitable permanent insulating barrier guards are used so that a person may not, while touching the ungrounded parts at the same time inadvertently touch other machine frames or metallic fixtures not bonded to the parts in question. This provision shall not apply to the motor frame of a direct connected, motor driven, high tension, series generator sets in existing installations, when the generators have their frames insulated from ground, for operating reasons, and the motor frames are grounded, if it is impracticable to provide insulating barrier guards in the space available. Reference should also be made to §  39.115 (relating to noncurrent-carrying parts).

 (d)  If exposed noncurrent-carrying metal parts are not grounded they shall be suitably insulated from the ground and from neighboring grounded surfaces.

 (a)  Adequate working space with secure footing shall be maintained about electrical supply equipment which requires adjustment or examination during operation.

 (b)  Working spaces about exposed live parts over 300 volts to ground shall be made inaccessible to other than authorized attendants by the use of suitable barriers when necessary.

 (c)  The spaces shall be arranged so as to give authorized attendants ready access to all parts requiring attention and if practicable, unless used only for infrequent construction, inspection, and repair, shall provide the following minimum working spaces:

   (1)  If there are exposed live parts from 300 volts up to 750 volts on one side, the minimum width shall be 2 1/2 feet; above 750 volts, not less than three feet.

   (2)  If there are exposed live parts from 300 volts up to 750 volts on the both sides, the minimum width shall be 3 feet; above 750 volts, not less than 5 feet.

 (a)  Protection shall be provided for persons near otherwise exposed ungrounded current-carrying parts of electrical supply equipment such as bus bars and other conductors on the terminals of generators and motors, operating at over 300 volts to ground and not effectively isolated by elevation unless these parts are away from passageways, and working spaces, used for frequent construction, inspection and repair.

 (b)  If the working space about electrical equipment is less than that specified in §  39.104 (relating to working space about electrical equipment), suitable enclosures or barriers shall be provided to prevent inadventent contact with live parts. If such enclosures must be opened or barriers removed while the parts they guard are alive, surrounding floors shall be provided with suitable insulating platforms or mats, so placed that the operator may not readily touch the live parts without standing on the mat or platform.

   (1)  Enclosures may consist of suitable casings or suitable insulating coverings. The insulating covering of conductors shall be depended upon only when it is impracticable to install more suitable guards and then only when very substantial, thoroughly dry, and containing no noninsulating flameproofing compound or oil-soaked rubber.

   (2)  Barriers may consist of horizontal or vertical strips placed in front of current-carrying parts or of closely spaced partitions between such parts, extending beyond the exposed sides of the current-carrying parts.

   (3)  If covers, casings or barriers are at any time removed while the parts which they guard are alive, they shall be of insulating material, or so arranged that they are not readily brought in contact with the live parts.

   (4)  Mats may be of wood, held together by wood pins, or of cork matting, linoleum or rubber. The material and construction should be suitable for the voltage concerned and for the prevailing conditions. If subject to moisture or to accumulations of conducting dust, flyings or chips, mats should provide surfaces minimizing the hazards from these sources.

 (c)  If the specified working spaces are provided and the current-carrying parts are not guarded by enclosures or barriers, the insulating platforms or mats shall always be provided.

 (d)  If the current-carrying parts operate at over 7500 volts the enclosing or barrier guards shall always be provided even if insulating mats are also provided. Enclosing or barrier guards not of grounded metal shall be of substantial material and spaced from the current-carrying parts not less than three times the needle-point sparking distance, at the voltage concerned, of the intervening air, oil, or other dielectric. This requirement shall not apply to direct-connected, motor-driven, high-tension, series generators, which for operating reasons have their frames insulated from ground.

 (e)  Bare parts at different potentials shall be effectively separated. Such parts in circuits of large capacity or operating at above 7500 volts shall, unless provided with enclosures or other guards specified in subsection (b), be provided with suitable barriers, if practicable, so that they will not be short- circuited by tools or other conducting objects.

 Current-carrying parts need not be guarded if they are maintained at the following distances above the floors which may be occupied by persons:

 (a)  Electrical supply equipment shall be suitably identified when necessary for safety. The identification may be by position, color, number, name, plate, label, design or other means.

 (b)  The voltage and intended use shall be shown when important.

ROTATING EQUIPMENT

§ 39.111. Speed control and stopping devices.

 (a)  Prime movers driving generating equipment shall be provided with automatic speed-limiting devices, in addition to their governors, if necessary, as with some types of steam turbines where harmful overspeed may otherwise occur.

 (b)  Separately excited direct current motors, series motors, and motor generators and converters, where possible for them to be driven at an excessive speed from the direct current end by a reversal of current or decrease of load, shall be provided with speed limiting devices, unless the load and the mechanical connections thereto are of such a character as to safely limit the speed.

 (c)  If the speed control of direct current motors is accomplished by varying the field resistance, and the nature of the load and the range of the field rheostat are such as to make a dangerous speed attainable and no speed limit devices are used, the field rheostats shall be arranged with no voltage releases or other devices so that the motor cannot be started or continued in operation under dangerously weakened field, except where a hazard to service or apparatus might result from operation if a hazard to service or apparatus might result from operation.

 (d)  Stopping devices, such as switches or valves which may be operated from locations convenient to machine operators, shall be provided from prime movers or motors driving generating equipment.

 (a)  Suitable insulating mats or platforms of substantial construction providing good footing shall be placed on floors and, if necessary, on frames of machines having exposed live parts above 300 volts to ground, so that no operator may readily touch such parts unless he is standing on the mat or platform.

 (b)  For parts above 750 volts, suitable enclosing or barrier guards shall, if practicable, be provided in addition to mats or platforms, and arranged such that the operator may not inadvertently touch the live parts and any neighboring grounded parts at the same time.

 (c)  If necessary, steps and handrails shall be installed on or about large machines to afford ready access to live parts which shall be examined or adjusted during operation.

 (d)  If switches are installed on the frames of generating equipment for the purpose of reducing inductive voltage in generator and converter field coils, they shall be suitably constructed or guarded to prevent passers by from inadvertently coming in contact with the live parts, to protect persons handling them, and to prevent them being accidentally opened or closed.

 (a)  If explosives, inflammable gas, or inflammable flyings normally exist in dangerous quantities, the parts at which sparking or arcing are liable to occur shall be enclosed so as to reduce the hazard as far as practicable. This enclosure shall be by any one of the following methods:

   (1)  Placement in separate compartments or rooms.

   (2)  Use of casings of enclosed type when inflammable dust or flyings are present.

   (3)  Use of explosion-proof casings when inflammable gasses exist in dangerous quantities.

 (b)  Casings shall be nonabsorptive and noncombustible, and if made of metal shall be permanently grounded if within reach of grounded surfaces.

 (a)  Exposed noncurrent-carrying metal parts of rotating electrical supply equipment shall be permanently grounded in accordance with the requirements for grounding provided in §  39.103 (relating to protective grounding).

 (b)  If machine frames, such as those of series are light generators or direct current railway generators, are necessarily ungrounded, suitable insulating floors, mats, or platforms providing good footing shall be so placed that no person may readily touch the machine frame unless standing on such floor, mat, or platform.

 (c)  If two or more machines, either of which operates at over 150 volts to ground, are mechanically coupled together and the operator is able to touch the frames of more than one at a time, the frames of all such shall be permanently grounded or bonded together electrically. This provision may be waived under the following circumstances:

   (1)  If high-voltage series generator sets in existing installations are used and for operating reasons the generators have their frames insulated from the ground and the motor frame is grounded.

   (2)  If it is impracticable to place insulating barriers between the grounded and ungrounded frames.

 (d)  Exciters and auxiliary circuits electrically connected to generators or other machines over 750 volts to ground (with frames ungrounded) shall be installed, protected, and identified as machines and circuits of the same voltage as that of the machine for which they are auxiliaries. Reference should also be made to §  39.132 (relating to grounding low voltage circuits of instrument transformers).

 (a)  Suitable guards or enclosures shall be provided to protect exposed current-carrying parts, insulation of leads, balancing coils or other electrical devices belonging to motors and generating equipment if installed directly under equipment or in other locations where dripping oil, excessive moisture, steam, vapors or similar injurious agents exist.

 (b)  The metal frames and other exposed noncurrent-carrying metal parts of equipment in these locations shall be permanently grounded.

STORAGE BATTERIES

§ 39.121. Applicability.

 The provisions of § §  39.121—39.127 (relating to storage batteries), except for §  39.125 (relating to guarding live parts in battery room), shall apply only to storage batteries exceeding 50 kilowatt hours capacity at the 8 hour rate of discharge.

 Storage batteries shall be made inaccessible to other than properly qualified persons by being placed in a separate room or enclosure.

 Rooms or enclosures containing storage batteries shall be ventilated so as to remove acid spray and prevent dangerous accumulation of inflammable gas. Communication of drafts to other rooms shall be prevented.

 The cells of storage batteries shall be supported by suitable insulators, except small cells of insulating material. Suitable drainage or other means shall be provided beneath cells to prevent the accumulation of electrolyte in case of leakage or spraying. Acid resistive floors, such as vitrified brick, set in pitch, are recommended where large batteries are installed.

 (a)  The arrangement of cells and connections shall be such that no two current-carrying parts between which a voltage exceeding 150 exists, shall be closer than three feet, if the parts are so exposed that persons are liable to make accidental contact with both at the same time.

 (b)  No conductor above 150 volts to ground shall be placed in any passageway, unless guarded or isolated by elevation.

 Storage battery rooms shall be lighted, if practicable, from outside lamps. If lamps are inside, only incandescent electric lamps in keyless porcelain or composition sockets, controlled from points not exposed to battery vapor, shall be used.

 Conductors in battery rooms, if of such material or so located as to be liable to corrosion, shall have suitable protective coverings or coatings, unless the ventilation is such as to render this unnecessary.

   This section cited in 34 Pa. Code §  39.85 (relating to general requirements); 34 Pa. Code §  39.121 (relating to applicability); and 34 Pa. Code §  39.201 (relating to storage batteries, transformers and lightning arresters).

TRANSFORMERS, REACTANCES, INDUCTION REGULATORS,
BALANCE COILS AND SIMILAR EQUIPMENT

§ 39.131. Current transformers secondary circuits.

 (a)  Secondary circuits of current transformers including constant current and instrument transformers, except those supplying relays only, or those having their primary circuits always disconnected before the secondary circuits are worked on, shall be provided with means of short circuiting them which may be readily connected while the primary is energized and which are so arranged as to permit the removal of any instrument or other device from such circuits without opening the circuits.

 (b)  If primaries are above 7,500 volts, secondary circuits, unless otherwise adequately protected from injury or contact of persons, shall be permanently grounded conduit.

 The low voltage circuit of instrument transformers shall be permanently grounded unless the circuits are installed, guarded, and plainly identified as required for the high voltage circuits of the transformers. This shall sometimes require marking to distinguish such a low voltage circuit from others with which it is associated, but which are protected by ground connections.

 (a)  The metal case or exposed frame of each transformer, reactance, and similar equipment, which is located where dampness or inflammable gas normally exists, or which is connected to a circuit operating at over 150 volts to ground, shall be permanently grounded.

 (b)  Exception is permissible in locations free from inflammable gas, if the entire transformer is isolated or guarded as required for the highest voltage circuit connected with the transformer, and is plainly and conspicuously identified as of that voltage.

 Transformers shall be installed according to any one of the following methods:

   (1)  On poles or, when permitted by local authority, on walls of buildings, in which case they shall comply with overhead line rules.

   (2)  In rooms in which other equipment is installed, in which case the construction, grounding, and guarding for live parts shall comply with the rules covering station construction or utilization equipment, as they may apply in each case.

   (3)  In transformer vaults or rooms which shall be made inaccessible to unauthorized persons.

   (4)  If the amount of oil in transformer casings is considerable and the transformers are located in buildings used for other than station purposes, they should be placed in suitable transformer vaults. Reference should also be made to §  39.201 (relating to storage batteries, transformers and lightning arresters).

   This section cited in 34 Pa. Code §  39.201 (relating to storage batteries, transformers and lightning arresters).

WIRING AND PROTECTION AND CONTROL EQUIPMENT

§ 39.141. Electrical protection from conductors.

 (a)  Conductors shall be suitable for the location, use, and voltage. Conductors shall be protected against excessive heating by the design of the system or by automatic cut-outs, unless grounded conductors, field excitation circuits, circuits supplying interconnected three wire systems of underground distribution, and other circuits the opening of which may cause special hazard to life through interruption of service. Such automatic cut-outs may be set so as to interrupt the circuits only on excessive short circuits, if constant attendance is provided and protection is thus also afforded by manual operation.

 (b)  Conductors normally grounded for the protection of persons shall be arranged without automatic cut-outs interrupting their continuity between the source of energy and the point at which the ground wire is attached, unless the operation of such a cut-out automatically results in the immediate disconnection of the grounded circuit from all sources of electrical energy.

 (c)  Conductors shall be provided with one or more suitable switches to effectively disconnect them from all sources of electrical energy.

 (a)  If exposed to mechanical injury, suitable casing, armor, or other means shall be employed to prevent injury or disturbances to conductors, their insulation, or supports.

 (b)  If conductors with insulating coverings are closely grouped, as sometimes on the rear of switchboards or in cableways, they shall have a substantial flameproof outer covering.

 All conductors over 750 volts, and ungrounded bare conductors over 300 volts to ground shall be isolated by elevation as required by §  39.106 (relating to isolating live parts by elevation), unless guarded in accordance with §  39.144 (relating to guarding conductors), so that no person may inadvertently come in contact with them. Buses and bus structures and line connections thereto, installed in accordance with § §  39.104 and 39.160 (relating to working space about electrical equipment; guarding live parts of switches and automatic cut-outs not installed on switchboards) in suitable locations specially arranged for such purposes, shall not be required to be so isolated.

 (a)  Use of enclosed casings. If insulated conductors are enclosed, suitable permanently grounded metal conduit or grounded metal sheating shall be used; or in lieu thereof other ducts, runways, or compartments of tile, bitumenized fiber, concrete, or other suitable fire-resistive materials may be used, if containing no exposed combustible material. In damp places, conduits, ducts, or runways shall be made waterproof and be provided with suitable means for draining off condensation, unless the conductors contained are lead-sheathed cables.

 (b)  Conductors above 750 volts in conduits or sheathing. Conductors operating at over 750 volts unless separately supported and effectively isolated by elevation or by enclosing in suitable compartments or screens, as in subsection (d), shall be suitable metal sheathed cable, run in metal conduits or suitable fire-resistive ducts or compartments, with the metal sheathing permanently grounded. Other covering may be used in suitable grounded metal conduit or insulating duct, when installed in dry locations. The conduit or duct shall provide a smooth runway with smooth outlets. Metal conduit, if used, shall be made electrically and mechanically continuous with the metal casings of conduit fittings.

 (c)  Metal sheathed cable outlets above 750 units. Insulation of the several conductors of multiple conductor cable, where leaving the metal sheath at outlets, shall be thoroughly protected from mechanical injury, moisture and electrical strains by means of a pot head or equivalent method.

 (d)  Open conductors above 750 volts. When any open insulated conductor above 750 volts, or any open bare conductor above 300 volts to ground, is necessarily brought closer to the floor line than the clearances required for isolation by elevation, they shall be guarded by permanent screens, by enclosing partitions, or by suitable barrier guards.

 (e)  If barrier rails only are used, the surrounding floors shall be provided with suitable insulating platforms, mats, or covers. Reference should also be made to §  39.105(b) (relating to guarding live parts).

 (a)  Conductors in locations where inflammable gas normally exists shall be in metal conduit or metal sheathed cable. Fittings and outlets of such conduit and cable shall be electrically and mechanically continuous with the conduit or metal sheath, and the conduit shall be sealed to prevent entrance of gases.

 (a)  Pendant conductors shall not be installed if they may readily be moved so as to bring them in contact with live parts of electrical supply equipment.

 Ends and joints of insulated conductors, unless otherwise adequately guarded, shall have equal insulating covering with other portions of the conductor.

FUSES AND OTHER CUT-OUTS, SWITCHES, AND CONTROLLERS

§ 39.151. Accessible and indicating.

 Switches, automatic cut-outs, starting rheostats and other control devices shall be readily accessible to authorized persons. They shall be arranged or marked so as to identify the equipment controlled by them, and, except fuses, shall indicate whether they are open or closed. They shall be installed so as to minimize the danger of accidental operation, and where practicable so that gravity can