section 26 05 26-earthing system.pdf

MINISTRY OF HOUSING Western Sector Projects Sitework & Infrastructure OMRANIA and ASSOCIATES Project Specification

EARTHING SYSTEM SECTION 26 05 26 - 1

SECTION 26 05 26

EARTHING SYSTEM PART 1: GENERAL

1.01 SECTION INCLUDES

A Earthing system including, but not limited to the following:

1. Earth rods.

2. Earth conductors.

3. Earth connection bar.

4. Earthing of various systems.

1.02 RELATED SECTIONS

A Section 01 31 00 Project Management and Coordination.

B Section 0133 00 Submittal Procedures.

C Section 01 61 00 Common Product Requirements.

D Section 01 78 36 Warranties.

E Section 26 05 00 Common Work Results for Electrical.

F Section 26 05 53 Electrical Identification.

G Section 26 05 19 LV Cables and Wires.

H Section 33 71 19 Underground Electrical Services.

I Section 26 11 13 Unit Substation.

J Section 26 08 00 Testing and Commissioning of Electrical Systems.

1.03 REFERENCES

A SASO Saudi Arabian Standards Organization.

B IEC 60364 Electrical Installations of Buildings.

C BS 7430 Code of Practice for Protective Earthing of Electrical Installations.

D BS 7671 Requirements for Electrical Installations (IEE Wiring Regulations).

E SEC DPS SEC Distribution Planning Standards.

F SEC SDMS SEC Distribution Materials Specifications.



G SEC SDCS SEC Distribution Construction Standards.

1.04 SUBMITTALS

A Comply with section 0133 00.

B Submit manufacturers data, illustrated leaflets, dimensions, fixing details and description of the proposed products.

1.05 QUALITY ASSURANCE

A Manufacturers: Firms regularly engaged in the manufacture of earthing equipment, whose products have been in satisfactory use in similar service for not less than 5 years. Preference shall be given to local manufacturers and suppliers/agents.

B Installer: Firms regularly engaged and qualified with at least 5 years of successful installation and experience on projects with installations similar to that required for this project.

C All equipment furnished under this Specification shall conform to the requirements of IEC, SASO and BS.

1.06 DELIVERY, STORAGE AND HANDLING

A Comply with 01 61 00.

B All products shall be carefully packed to avoid damage during transportation.

1.07 WARRANTY

A Comply with section 01 78 36.

1.08 SEC/MUNICIPALITY COMPLIANCE

A Contractor shall comply with all applicable SEC distribution material specification, construction and planning standards for power distribution networks and municipality specification for road lighting. Some of the specifications and standards are attached with the contract documents for guidance, however contractor shall obtain copy of all applicable specification and standards from the concerned authorities as required on site or instructed by the Engineer.

B Any conflict found between this project specification and SEC or municipality specification/standards shall be immediately brought to the notice of Engineer for final decision.

PART 2: PRODUCTS

2.01 ACCEPTABLE MANUFACTURERS

Not Used.

2.02 GENERAL

A All materials required for earthing system shall be furnished new and undamaged in accordance with the requirements stated in this section.



B Conduct soil electrical resistivity tests at four locations (minimum) to be advised by the Engineer. The earthing calculations based on the test results shall be submitted for Engineers approval, to demonstrate that the proposed design of the earthing system complies with the Specification and standards.

C A connection shall be provided from the main earth loop for medium voltage equipment in the electricity supply authority incoming equipment room, Earth pits shall be installed in accordance with the requirements of the electricity supply authority having jurisdiction, which shall be isolated from the main earth loop.

D Separate earth pits shall be installed in communications rooms, in accordance with requirements of the telecommunications utility supply authority having jurisdiction, which shall be isolated from the main earth loop.

2.03 EARTH RODS

A Earth rods of the 'copper-weld' (copper-clad rods constructed with a minimum 0.25 mm thick copper exterior sleeve inseparably and permanently molten-welded to a central high tensile steel core for rigidity) type shall be used.

B Earth electrodes for each system shall have an interconnected resistance to earth of not more than 5 Ohms. Where this value is exceeded, the system shall be augmented by additional electrodes connected in parallel spaced at approximately four meters apart until this value is reached.

C The diameter and length of earth rods shall be as per details shown on drawings or as approved by the Engineer.

2.04 EARTH CONDUCTORS

A Size of earth conductors shall be as shown on the drawings and in accordance with applicable standards.

B Earth conductors shall be as follows:

1. Outdoor Underground: Soft drawn bare high conductivity annealed plain stranded copper conductor.

2. Inside Building: Same as for outdoor conductor but with green/yellow colored Poly Vinyle Chloride (PVC) insulation.

C PVC insulated copper conductor cable shall be used for final connections from earth loop to structures, equipment, etc and for earthing/bonding of equipment and metalwork inside the building.

D All copper to copper connections, splices, taps, etc. in conductors and at accessories for termination shall be made by the exothermic weld process. Joints for underground installation shall be epoxy resin encapsulated before burial.

E Earth conductor in the conduit shall be continuous through the conduit run with bushing earth connection and terminated on the panel board earthing.

2.05 EARTH CONNECTION BAR

A For connection of MV and LV equipment, each sub-station shall have high conductivity



copper, earth connection bar with minimum dimensions of 50 x 6 mm and mounted on porcelain insulators. The bar shall be of suitable length with pre-drilled holes at a minimum distance of 50 mm between hole centres.

B Earth connection bars for transformer neutral and LV switchboard frame shall be separate from earth bar for MV and transformer frame.

C MV generator frame and neutral shall be connected to the same earth connection bar.

D Each earth connection bar shall have a permanent label to identify the connections, together with the wording "Main Earth Bar".

PART 3: EXECUTION

3.01 INSPECTION


B Examine the area and conditions under which the earthing systems are to be installed and correct any unsatisfactory conditions detrimental to the timely and proper completion of the work. Do not proceed with the work until unsatisfactory conditions have been corrected in a manner acceptable to the Engineer.

3.02 GENERAL INSTALLATION REQUIREMENTS

A The installation shall be carried out in accordance with IEC. The position of all conductors, joints and terminals shall be approved by the Engineer prior to commencing the work.

B All electrical equipment shall be connected to the earth with copper earth conductor. The term "electrical equipment" shall include all metal enclosures containing electrical connections or bare conductors. Individual devices such as solenoids, pressure switches, and limit switches shall be exempt from this requirement unless the device requires earthing for proper operation. Large equipment such as power distribution boards or motor control centers shall be furnished with an earthing bus, which shall be connected at two points to the earth. All earth connection surfaces shall be cleaned immediately prior to connection. Provide all earthing material required but not furnished with the equipment.

C All exposed non-current carrying metallic parts of all installations shall be effectively earthed. Steel conduit systems, metallic equipment enclosures, metallic lighting fixtures, cable trays, all non-current carrying metal parts of electrical systems and any other equipment or system components shall be earthed and the connection shall be extended to the nearest panel board earth or earthing bar in the sub-station.

D The conductive sheaths and armor of cables shall be connected to earth.

E All connections and joints for the earthing system including bonding connections shall be made using the "Exothermic" process to produce a fused joint.

3.03 EARTH ROD INSTALLATION

A All earth rods shall be installed at suitable locations and to a depth to achieve the required resistance. Where the earth rod length exceeds 2.5 m, standard sections shall be connected with aluminum bronze coupling to extend the rod.



B Earth rods shall be driven with a cap driving stud.

C All connections between rods and earthing conductors shall be made by removable bolted connections.

D All earth rods shall have inspection pits as shown on the Drawings. Inspection pits shall be constructed from pre-cast concrete. All connections to the earth rod shall be exposed when the cover is raised. Attach a DANGER - ELECTRICITY sign to the wall of the inspection pit. Use English and Arabic white letters on red background. Inspection pit cover shall be constructed from cast iron.

3.04 EARTH CONDUCTOR INSTALLATION

A Provide standard sizes of bare or PVC insulated stranded copper conductor for earth continuity as required and approved by the Engineer, whether shown on the drawings or not.

B Suitable earthing facilities acceptable to the Engineer shall be furnished on electrical equipment to consist of compression type terminal connectors bolted to the equipment frame or enclosure and providing a minimum of joint resistance.

C The conduit system shall not be considered as continuous for earthing purposes. A separate

earth conductor shall be installed in the same conduit with the phase and neutral conductors. The separate earth conductors shall be sized according to calculated short circuit current and applicable standards. No earthing conductors shall be smaller than 2.5 mm2

D Exposed conductors shall be installed inconspicuously in vertical or horizontal positions on supporting structures. When located on irregular supporting surfaces or equipment, the conductors shall run parallel to or normal to the dominant surface.

unless this is part of a multi-core cable. Where flexible connections are made to equipment, earthing jumpers shall be provided. All connections of heavy gauge steel conduit system shall be checked for good electrical continuity.

E Conductors routed over concrete, steel or equipment surfaces shall be kept in close contact with those surfaces by using fasteners located at intervals not exceeding 1 meter.

F Exposed earthing conductors shall be securely fastened to the mounting surface using copper or brass straps.

G Clamps, connectors, bolts, washers, nuts and other hardware for bolted connection to earthing system shall be of copper.

H Exothermic welds shall comprise molds, cartridges, materials, and accessories as recommended by the manufacturer.

I Earthing conductors entering the building shall be installed in a 25 mm diameter PVC conduit. Waterproofing shall be provided at all entries of earth conductors, details of which shall be approved by the structural engineer.

J Earth conductors shall be buried at a minimum depth of 750 mm below finished grade.

K Underground conductors shall be buried in clean sifted earth.

L Except for sub-stations and electrical rooms, the exposed earth conductor shall run in protective pipes for runs below 900 mm from floor level. Pipes shall also be provided at locations where conductor is likely to be subject to physical damage.



M Extensions from the earth loop as shown on the Drawings shall be provided for connection to electrical equipment. Connect the earthing conductor to equipment, earth bus, pad or lug. In addition to the earth grid extension conductors, an earth cable to each end of the earth bus in each assembly of power distribution board or panel boards shall be provided.

N Where an earth conductor is included with the phase conductors of power circuits, the earth conductor shall be connected to the equipment earthing facilities and to the source earth bus. Where an earth conductor is not included with the phase conductors, the equipment shall be earthed by connecting a separate earth cable to the equipment earthing facilities and to the tray earthing cable or source earth bus.

3.05 EARTH LOOP IMPEDANCE

A The completed earthing system shall have sufficiently low impedance to limit the voltage to earth and to facilitate the operation of the current protective devices in the circuit. Earth loop impedance shall not exceed the values specified in BS or other applicable standards.

3.06 BUILDING SYSTEMS EARTHING

A Building low current systems including communication, control and alarm functions shall be provided with earthing as shown on the drawings and in the relevant specification section. Where applicable, requirements of functional earthing shall also be complied with.

B The installation of earthing for building systems shall be in accordance with the recommendations of standards, and the applicable provisions of this section.

3.07 SUPPLEMENTARY AND EQUI-POTENTIAL BONDING

A In accordance with Section 547 of the IEE Wiring Regulations (BS 7671), bonding conductors shall be installed in appropriate locations to ensure all simultaneously accessible exposed or extraneous conductive parts are at equal potential. Undertake such tests and install such supplementary bonding conductors that are necessary to ensure compliance with these requirements.

B Supplementary bonding conductors shall conform to the requirements of section 547-03 of the IEE Wiring Regulations and shall have a minimum cross-sectional area of 2.5 mm2 where mechanically protected and 4.0 mm2

C Main equi-potential bonding conductors shall conform to the requirements of section 547-2 of the IEE Wiring Regulations and shall have a minimum cross-sectional area of 6.0 mm

where not so protected.

2

3.08 FIELD QUALITY CONTROL

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B Earth resistance tests shall be carried out after installation of the individual earthing systems in accordance with the specification. Earth resistance tests shall be carried out in accordance with section 713-11 of the IEE wiring regulations 16th edition and the readings obtained shall be officially recorded by all witnessing parties.

C Prior to connection of earth rods to the earthing system, the earth resistance of individual earth rods shall be measured by using an approved type of earth resistance tester.

D After completion of all connections of the earthing system, the earth resistance shall be measured from the earthing test point in the presence of the Engineer.



E In addition to above, carry out any test(s) required to comply with the procedures of the electricity supply authority (SEC) for power connection requirements.

F All earth resistance test reports shall be submitted for the Engineers approval.

END OF SECTION

SECTION 26 05 26PART 1: GENERALSECTION INCLUDESContractor shall comply with all applicable SEC distribution material specification, construction and planning standards for power distribution networks and municipality specification for road lighting. Some of the specifications and standards are att...Any conflict found between this project specification and SEC or municipality specification/standards shall be immediately brought to the notice of Engineer for final decision.

PART 2: PRODUCTSGENERALAll materials required for earthing system shall be furnished new and undamaged in accordance with the requirements stated in this section.

EARTH RODsEarth rods of the 'copper-weld' (copper-clad rods constructed with a minimum 0.25 mm thick copper exterior sleeve inseparably and permanently molten-welded to a central high tensile steel core for rigidity) type shall be used.Earth electrodes for each system shall have an interconnected resistance to earth of not more than 5 Ohms. Where this value is exceeded, the system shall be augmented by additional electrodes connected in parallel spaced at approximately four meters a...

Earth conductorsSize of earth conductors shall be as shown on the drawings and in accordance with applicable standards.Earth conductors shall be as follows:PVC insulated copper conductor cable shall be used for final connections from earth loop to structures, equipment, etc and for earthing/bonding of equipment and metalwork inside the building.All copper to copper connections, splices, taps, etc. in conductors and at accessories for termination shall be made by the exothermic weld process. Joints for underground installation shall be epoxy resin encapsulated before burial.Earth conductor in the conduit shall be continuous through the conduit run with bushing earth connection and terminated on the panel board earthing.

earth connection bar

PART 3: EXECUTIONINSPECTIONExamine the area and conditions under which the earthing systems are to be installed and correct any unsatisfactory conditions detrimental to the timely and proper completion of the work. Do not proceed with the work until unsatisfactory conditions ha...

general installation requirementsAll electrical equipment shall be connected to the earth with copper earth conductor. The term "electrical equipment" shall include all metal enclosures containing electrical connections or bare conductors. Individual devices such as solenoids, pressu...All exposed non-current carrying metallic parts of all installations shall be effectively earthed. Steel conduit systems, metallic equipment enclosures, metallic lighting fixtures, cable trays, all non-current carrying metal parts of electrical system...The conductive sheaths and armor of cables shall be connected to earth.All connections and joints for the earthing system including bonding connections shall be made using the "Exothermic" process to produce a fused joint.

earth rod INSTALLATIONAll earth rods shall be installed at suitable locations and to a depth to achieve the required resistance. Where the earth rod length exceeds 2.5 m, standard sections shall be connected with aluminum bronze coupling to extend the rod.Earth rods shall be driven with a cap driving stud.All connections between rods and earthing conductors shall be made by removable bolted connections.All earth rods shall have inspection pits as shown on the Drawings. Inspection pits shall be constructed from pre-cast concrete. All connections to the earth rod shall be exposed when the cover is raised. Attach a DANGER - ELECTRICITY sign to the wa...

EARTH CONDUCTOR INSTALLATIONProvide standard sizes of bare or PVC insulated stranded copper conductor for earth continuity as required and approved by the Engineer, whether shown on the drawings or not.Suitable earthing facilities acceptable to the Engineer shall be furnished on electrical equipment to consist of compression type terminal connectors bolted to the equipment frame or enclosure and providing a minimum of joint resistance.The conduit system shall not be considered as continuous for earthing purposes. A separate earth conductor shall be installed in the same conduit with the phase and neutral conductors. The separate earth conductors shall be sized according to calculat...Exposed conductors shall be installed inconspicuously in vertical or horizontal positions on supporting structures. When located on irregular supporting surfaces or equipment, the conductors shall run parallel to or normal to the dominant surface.Conductors routed over concrete, steel or equipment surfaces shall be kept in close contact with those surfaces by using fasteners located at intervals not exceeding 1 meter.Exposed earthing conductors shall be securely fastened to the mounting surface using copper or brass straps.Clamps, connectors, bolts, washers, nuts and other hardware for bolted connection to earthing system shall be of copper.Exothermic welds shall comprise molds, cartridges, materials, and accessories as recommended by the manufacturer.Earthing conductors entering the building shall be installed in a 25 mm diameter PVC conduit. Waterproofing shall be provided at all entries of earth conductors, details of which shall be approved by the structural engineer.Earth conductors shall be buried at a minimum depth of 750 mm below finished grade.Underground conductors shall be buried in clean sifted earth.Except for sub-stations and electrical rooms, the exposed earth conductor shall run in protective pipes for runs below 900 mm from floor level. Pipes shall also be provided at locations where conductor is likely to be subject to physical damage.Extensions from the earth loop as shown on the Drawings shall be provided for connection to electrical equipment. Connect the earthing conductor to equipment, earth bus, pad or lug. In addition to the earth grid extension conductors, an earth cable to...Where an earth conductor is included with the phase conductors of power circuits, the earth conductor shall be connected to the equipment earthing facilities and to the source earth bus. Where an earth conductor is not included with the phase conducto...

EARTH LOOP IMPEDANCEThe completed earthing system shall have sufficiently low impedance to limit the voltage to earth and to facilitate the operation of the current protective devices in the circuit. Earth loop impedance shall not exceed the values specified in BS or oth...Prior to connection of earth rods to the earthing system, the earth resistance of individual earth rods shall be measured by using an approved type of earth resistance tester.After completion of all connections of the earthing system, the earth resistance shall be measured from the earthing test point in the presence of the Engineer.

section 26 05 26-earthing system.pdf

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