1.7.90. Connections of grounding and zero protective conductors to each other must ensure reliable contact and be carried out by welding.

It is allowed indoors and in outdoor installations without aggressive environments to connect grounding and neutral protective conductors in other ways that ensure the requirements of GOST 10434-82 "Contact electrical connections. General technical requirements" for the 2nd class of connections. At the same time, measures must be taken to prevent weakening and corrosion of contact connections. Connections of grounding and zero protective conductors of electrical wiring and overhead lines are allowed to be performed by the same methods as for phase conductors.

Connections of grounding and zero protective conductors must be accessible for inspection.

1.7.91. Steel pipes of electrical wiring, boxes, trays and other structures used as grounding or zero protective conductors must have connections that meet the requirements of GOST 10434-82 for the 2nd class of connections. Reliable contact of steel pipes with electrical equipment housings into which pipes are inserted, and with metal junction (branch) boxes must also be ensured.

1.7.92. The places and methods of connecting grounding conductors with extended natural grounding conductors (for example, with pipelines) must be chosen so that when the grounding conductors are disconnected for repair work, the calculated value of the resistance of the grounding device is provided. Water meters, gate valves, etc. must have bypass conductors to ensure continuity of the ground circuit.

1.7.93. The connection of grounding and zero protective conductors to parts of the equipment to be grounded or grounded must be done by welding or bolting. The connection must be accessible for inspection. For bolted connection, measures must be taken to prevent loosening and corrosion of the contact connection.

Grounding or grounding of equipment that is subject to frequent dismantling or installed on moving parts or parts subject to shock or vibration must be carried out with flexible grounding or zero protective conductors.

1.7.94. Each part of the electrical installation to be grounded or grounded must be connected to the grounding or grounding network using a separate branch. Consistent connection to the grounding or zero protective conductor of the grounded or grounded parts of the electrical installation is not allowed.

Portable electrical receivers

1.7.95. Portable electrical receivers should be powered from a mains voltage not exceeding 380/220 V.

Depending on the category of the premises according to the level of danger of electric shock to people (see Chap. 1.1), portable electrical receivers can be powered either directly from the mains, or through isolation or step-down transformers (see 1.7.44).

Metal cases of portable power receivers above 42 V AC and above 110 V direct current in rooms with increased danger, especially dangerous and in outdoor installations, they must be grounded or grounded, with the exception of electrical receivers with double insulation or powered by isolating transformers.

1.7.96. Grounding or grounding of portable electrical receivers should be carried out with a special core (the third one - for single-phase and direct current electrical receivers, the fourth - for three-phase current electrical receivers), located in the same sheath with the phase conductors of the portable wire and attached to the body of the electrical receiver and to the special contact of the plug-in connector (see 1.7.97). The cross section of this core must be equal to the cross section of the phase conductors. The use of a zero working conductor for this purpose, including one located in a common shell, is not allowed.

Due to the fact that GOST for some brands of cables provides for a reduced cross section of the fourth core, it is allowed to use such cables for three-phase portable electrical receivers until the corresponding change in GOST.

The conductors of wires and cables used for grounding or grounding of portable electrical receivers must be copper, flexible, with a cross section of at least 1.5 mm for portable electrical receivers in industrial installations and at least 0.75 mm for household portable electrical receivers.

1.7.97. Portable power receivers of test and experimental installations, the movement of which is not provided for during their operation, is allowed to be grounded using stationary or separate portable grounding conductors. In this case, stationary grounding conductors must meet the requirements of 1.7.73 - 1.7.89, and portable grounding conductors must be flexible, copper, with a cross section not less than the cross section of phase conductors, but not less than that specified in 1.7.96.

In plug-in connectors of portable electrical receivers, extension wires and cables, conductors must be connected to the socket from the side of the power source, and to the plug - from the side of electrical receivers.

Plug-in connectors must have special contacts to which grounding and neutral protective conductors are connected.

The connection between these contacts at switch-on must be established before the contacts of the phase conductors come into contact. The order of disconnection of contacts during disconnection must be reversed.

The design of plug-in connectors must be such that the possibility of connecting the contacts of the phase conductors to the grounding (zeroing) contacts is included.

If the body of the plug-in connector is made of metal, it must be electrically connected to the earth (neutral) contact.

1.7.98. Grounding and zero protective conductors of portable wires and cables must have a distinctive feature.

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The connection of grounding conductors to grounded structures must be carried out by welding, and the connection to the bodies of apparatuses, machines, etc. - by welding or a reliable bolted connection. The mechanical strength of welded joints is checked by hammer blows.

The connection of grounding conductors to the grounding conductor and grounded structures must be carried out by welding, and to the bodies of apparatuses, machines and supports overhead lines power transmission - by welding or bolting.

The connection of grounding conductors to grounding conductors, the grounding loop and to grounded structures must be carried out by welding, and to the bodies of apparatuses, machines and overhead line supports - by welding or reliable bolted connection.

Grounding conductors are connected to the housings of electric motors and apparatuses, as well as to various parts of the electrical installation to be grounded, with bolts.

The connection of grounding conductors to grounding conductors, as well as the connection of grounding conductors to each other, must be carried out by welding. In this case, the length of the overlap (the length of the welds) should be equal to twice the width of the conductor with a rectangular section and six of its diameters with a round section.

The connection of grounding conductors to grounded structures and to the bodies of boxes, boxes and apparatuses, in all possible cases, is carried out by electric welding or bolted connections.

The connection of grounding conductors to pipelines, where welding can cause their deformation, is allowed using steel strip clamps with a thickness of at least 4 mm, while the contact surface of the pipeline is cleaned to a metallic sheen.

Connection of grounding conductors to metal sheaths of cables and wires should be carried out by soldering.

The grounding conductors are connected to the sheaths and armor of the cables before the insulating windings are applied to the root of the cut or the funnel is pushed onto the cut. For cables with paper insulation, the connection is made after the insulation of the cores.

Connections and connections of grounding, protective conductors and conductors of the potential equalization and equalization system must be reliable and ensure continuity electrical circuit. Connections of steel conductors are recommended to be made by welding. It is allowed indoors and outdoors without aggressive environments to connect grounding and neutral protective conductors in other ways that ensure the requirements of GOST 10434 "Contact electrical connections. General technical requirements" for the 2nd class of connections.

Connections must be protected from corrosion and mechanical damage.

For bolted connections, measures must be taken to prevent contact loosening.

1.7.140

Connections must be accessible for inspection and testing, with the exception of compounds filled with compound or sealed, as well as welded, soldered and crimped connections to heating elements in heating systems and their connections located in floors, walls, ceilings and in the ground.

1.7.141

When using devices for monitoring the continuity of the ground circuit, it is not allowed to connect their coils in series (in a cut) with protective conductors.

1.7.142

Connections of grounding and neutral protective conductors and potential equalization conductors to open conductive parts must be made using bolted connections or welding.

Connections of equipment subject to frequent dismantling or installed on moving parts or parts subject to shock and vibration must be made using flexible conductors.

Connections of protective conductors of electrical wiring and overhead lines should be carried out by the same methods as the connections of phase conductors.

When using natural ground electrodes for grounding electrical installations and third-party conductive parts as protective conductors and potential equalization conductors, contact connections should be made using the methods provided for by GOST 12.1.030 "SSBT. Electrical safety. Protective earth, zeroing"

1.7.143

The places and methods of connecting grounding conductors to extended natural grounding conductors (for example, to pipelines) should be chosen so that when the grounding conductors are disconnected for repair work, the expected contact voltages and the calculated values ​​​​of the resistance of the grounding device do not exceed safe values.

Shunting of water meters, valves, etc. should be carried out using a conductor of the appropriate cross section, depending on whether it is used as a protective conductor of a potential equalization system, a neutral protective conductor or a protective earth conductor.

1.7.144

The connection of each open conductive part of the electrical installation to the zero protective or protective earth conductor must be carried out using a separate branch. Sequential connection of open conductive parts into the protective conductor is not allowed.

The connection of conductive parts to the main potential equalization system must also be carried out using separate branches.

The connection of conductive parts to an additional potential equalization system can be performed using both separate branches and connection to one common permanent conductor.

1.7.145

It is not allowed to include switching devices in the circuit PE- and PEN- conductors, with the exception of cases of supplying electrical receivers with the help of plug connectors.

It is also allowed to simultaneously disconnect all conductors at the input to electrical installations of individual residential, country and garden houses and similar objects powered by single-phase branches from overhead lines. At the same time, the division PEN- conductor on PE- and - conductors must be made before the introductory protective switching device.

1.7.146

If the protective conductors and/or potential equalization conductors can be disconnected using the same plug connector as the corresponding phase conductors, the socket and plug of the plug connector must have special protective contacts for connecting protective conductors or potential equalization conductors to them.

If the housing of the socket outlet is made of metal, it must be connected to the protective contact of this socket.

Connections and connections of grounding, protective conductors and conductors of the potential equalization and equalization system

1.7.139. Connections and connections of grounding, protective conductors and conductors of the potential equalization and equalization system must be reliable and ensure the continuity of the electrical circuit. Connections of steel conductors are recommended to be made by welding. It is allowed indoors and in outdoor installations without aggressive media to connect grounding and neutral protective conductors in other ways that ensure the requirements of GOST 10434 “Electrical contact connections. General technical requirements” for the 2nd class of connections.

Connections must be protected from corrosion and mechanical damage.

For bolted connections, measures must be taken to prevent contact loosening.

1.7.140. Connections must be accessible for inspection and testing, with the exception of compounds filled with compound or sealed, as well as welded, soldered and crimped connections to heating elements in heating systems and their connections located in floors, walls, ceilings and in the ground.

1.7.141. When using devices for monitoring the continuity of the ground circuit, it is not allowed to connect their coils in series (in a cut) with protective conductors.

1.7.142. Connections of grounding and neutral protective conductors and potential equalization conductors to open conductive parts must be made using bolted connections or welding.

Connections of equipment subject to frequent dismantling or installed on moving parts or parts subject to shock and vibration must be made using flexible conductors.

Connections of protective conductors of electrical wiring and overhead lines should be carried out by the same methods as the connections of phase conductors.

When using natural grounding conductors for grounding electrical installations and third-party conductive parts as protective conductors and potential equalization conductors, contact connections should be made using the methods provided for by GOST 12.1.030 “SSBT. Electrical safety. Protective grounding, zeroing.

1.7.143. The places and methods of connecting grounding conductors to extended natural grounding conductors (for example, to pipelines) should be chosen so that when the grounding conductors are disconnected for repair work, the expected contact voltages and the calculated values ​​​​of the resistance of the grounding device do not exceed safe values.

Shunting of water meters, valves, etc. should be carried out using a conductor of the appropriate cross section, depending on whether it is used as a protective conductor of a potential equalization system, a neutral protective conductor or a protective earth conductor.

1.7.144. The connection of each open conductive part of the electrical installation to the zero protective or protective earth conductor must be carried out using a separate branch. Sequential connection of open conductive parts into the protective conductor is not allowed.

The connection of conductive parts to the main potential equalization system must also be carried out using separate branches.

The connection of conductive parts to an additional potential equalization system can be performed using both separate branches and connection to one common permanent conductor.

1.7.145. It is not allowed to include switching devices in the circuit RE- and PEN- conductors, with the exception of cases of supplying electrical receivers with the help of plug connectors.

It is also allowed to simultaneously disconnect all conductors at the input to electrical installations of individual residential, country and garden houses and similar objects powered by single-phase branches from overhead lines. At the same time, the division PEN- conductor on RE- and N- conductors must be made before the introductory protective switching device.

1.7.146. If the protective conductors and/or potential equalization conductors can be disconnected using the same plug connector as the corresponding phase conductors, the socket and plug of the plug connector must have special protective contacts for connecting protective conductors or potential equalization conductors to them.

If the body of the socket outlet is made of metal, it must be connected to the protective contact of this socket.

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The internal grounding network is carried out by open laying indoors along the construction surfaces of bare steel conductors with rectangular and round sections.

Openly laid bare ground conductors are located vertically, horizontally or parallel to sloping building structures. Conductors with a rectangular cross section are installed with a large plane to the surface of the base. On straight sections of the gasket, the conductors should not have irregularities and bends that are noticeable to the eye. Grounding conductors laid on concrete or brick in dry rooms that do not contain caustic vapors and gases are fixed directly on the walls, and in damp, especially damp rooms with caustic vapors and gases - on supports at a distance of at least 10 mm from the wall surfaces. In the channels, grounding conductors are located at a distance of at least 50 mm from the lower surface of the removable floor. The distance between supports for fixing grounding conductors on straight sections is 600...1000 mm.

Grounding conductors in places where they cross with cables and pipelines, as well as in other places where mechanical damage is possible, are protected by pipes or other means.

In the premises, grounding conductors should be available for inspection, but this requirement does not apply to neutral conductors and metal sheaths of cables, hidden electrical wiring pipelines and metal structures located in the ground. Through the walls, grounding conductors are laid in open openings, pipes or other rigid frames.

Each grounded element of the electrical installation must be connected to the grounding line using a separate branch. Serial connection to the grounding conductor of several grounded elements is prohibited.

Neutrals of transformers, grounded tightly or through devices that compensate for capacitive current, are connected to the ground electrode system or prefabricated grounding buses using separate grounding conductors.

Grounded terminals secondary windings measuring transformers are attached to their casings with grounding bolts. Flexible jumpers that serve to ground metal sheaths and cable armor are attached to them with a wire bandage and soldered, and then connected by bolted contacts to the cable termination (sleeve) and the grounding structure. The cross sections of flexible jumpers must correspond to the cross sections of the grounding conductors adopted for this electrical installation. The points of connection of the grounding jumper with the aluminum sheath of the cable are covered with asphalt varnish or hot bitumen after soldering.

The connection of grounding conductors with each other and their connection to the installation structures is carried out by welding, and the connection to the bodies of apparatus and machines is carried out by welding or a reliable bolted connection. Locknuts, spring washers, etc. are installed to prevent loosening of contact during shocks and vibrations.

Contact surfaces on grounded electrical equipment at the points of connection of grounding conductors, as well as contact surfaces between grounded equipment and the structures on which it is installed, must be cleaned to a metallic sheen and covered with a thin layer of petroleum jelly.