EARTHING
PART 1 - GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including General and
Supplementary Conditions and Division-1 Specification sections, apply
to work of this section.
B. Requirements of the following Division 16 Sections apply to this Section:
1. "Basic Electrical Materials and Methods."
1.02 SUMMARY:
A. Description of Work: this section includes complete installations to earth
every source of energy and to provide protective earthing and equipotential
bonding, including but not limited to the following::
1. Transformer neutral earthing
2. Main earthing terminals or bars
3. Exposed conductive parts of electrical equipment
4. Extraneous conductive parts
5. Standby generator neutral earthing.
6. Supplementary earthing bars.
B. Related Sections: the following sections contain special requirements that
relate to this section:
1. Division 13 for "Security Systems" earthing
2. Division 14 for "Dumbwaiters," "Elevators", "Escalators", and
"Materials Handling
3. Division 15 for "Mechanical Equipment & Installation"
4. Division 16 for "Wires and Cables" for earthing system.
5. Division 16 for "Lightning Protection System".
1.03 DEFINITIONS OF TERMS
A. "Grounding" or "Ground" used in other sections or divisions of the
specification are interchangeably used as "Earthing" or "Earth".
B. Earth: conductive mass of the Earth whose electric potential at any point is
conventionally taken as zero.
2
C. Earth Electrode: conductor or group of conductors in initial contact with,
and providing electrical connection to, Earth.
D. Exposed Conductive Part: any part which can be readily touched and which
is not a live part, but which may become live under fault conditions.
E. Extraneous Conductive Part: any conductive part not forming part of the
electrical installation such as structural metalwork of a building, metallic
gas pipes, water pipes, heating tubes etc. and non-electrical apparatus
electrically connected to them i.e. radiators, cooking ranges, metal sinks etc.
and non-insulating floors and walls.
F. Protective Conductor: conductor used for some measure of protection
against electric shock and intended for connecting together any of the
following parts:
exposed conductive parts
extraneous conductive parts
earth electrode(s)
main earthing terminal or bar(s)
earthed point of the source(s)
G. Electrically Independent Earth Electrodes: earth electrodes located at such
distance from one another that maximum current likely to flow through one
of them does not significantly affect the potential of the other(s).
H. Main Earthing Terminal or Bar: the terminal or bar provided for the
connection of protective conductors, including equipotential bonding and
functional earthing conductors if any to the means of earthing.
I. Equipotential Bonding: electrical connection to put exposed and extraneous
conductive parts at a substantially equal potential.
J. Earthing Conductor: protective conductor connecting main earthing
terminal or bar of an installation to earth electrode or to other means of
earthing.
1.04 SUBMITTALS:
A. General: submit the following in accordance with Conditions of Contract
and Division 1 Specification Sections.
B. Product Data: for earth rods, connectors and connection materials, and
earthing fittings.
C. Equipment Data: prior to ordering materials, submit data for approval
including, but not limited to, manufacturer's catalogues for earth rods,
connecting clamps, earthing conductors, protective conductors, bonding
conductors, connectors and other accessories, exothermic welding kits and
tools etc., and samples of conductors as requested.
3
D. Shop and Construction Drawings: submit drawings for approval including,
but not limited to, the following:
1. Exact location of earth pits, rods and details of installation and
connections,
2. Exact routing of buried earthing conductors with indication of crosssection,
depth of laying and covering,
3. Cross sectional area and exact routing of all earthing, protective and
bonding conductors,.
4. Layout and details of earthing provisions at substations, generator
rooms, switchgear, distribution panelboards, low current rooms etc.,
indicating fittings used, insulation, plates and marking, passage and
routing of earthing conductors, conduit, sleeves, grooves, niches etc.,
giving sizes and dimensions of component parts.
E. Field Testing Organization Certificate: signed by the Contractor, certifying
that the organization performing field tests complies with the requirements
specified in Quality Assurance below.
F. Report of field tests and observations certified by the testing organization.
G. Report of field tests and observations certified by the Engineer. (All tests
shall be carried out in the presence of and be certified by the Engineer.
H. Samples: Submit sample of earthing cables and earthing accessories.
I. Calculations: submit detailed calculations verifying the earth resistance
value considering the soil conditions.
1.05 QUALITY ASSURANCE:
A. Manufacturer's Qualifications: Firms regularly engaged in the manufacture
earthing products, of types, and ratings required, and ancillary materials,
including stranded cable, copper braid and bus and bonding jumpers whose
products have been in satisfactory use in similar service for not less than 5
years.
B. Standards Compliance: Comply with requirements of applicable local
codes, IEC 61364-5 and IEE wiring regulations 16th edition pertaining to
electrical earthing system and equipment.
C. Regulations and Standards: carry out work in accordance with the
following:
1. IEC publications 364-3 and 364-4-41, Electrical Installations in
Buildings
2. BS7671:1992 Requirements for Electrical Installations (IEE Wiring
Regulations).
3. BS 7430 Earthing code of pratiace.
D. Field-Testing Organization Qualifications: to qualify for acceptance, the
independent testing organization must demonstrate, based on evaluation of
organization-submitted criteria , that it has the experience and capability to
conduct satisfactorily the testing indicated.
E. Egyptian Building codes & regulations.
4
PART 2 - PRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements,
specifications, regulations and drawings.
B. For recommended manufacturers refer to the list of recommended
manufactures.
2.02 ELECTRODES
A. Earthing system will be provided for the earthing of the entire development
including the L.V switchgears, panel boards, electrical circuits, building
structure, bonding …etc and associated equipments.
B. Earthing rods will be installed as indicated in the drawings with cable
connection to earthing equalizer/bars.
C. Earth rods shall be of circular cross-section copper bond type and as
indicated shall be jointed with purpose made couplings and a suitable
driving cap and tip shall be fitted to the rod. Couplings shall not exceed the
diameter of the rod.
D. Rod section couplings, driving cap and tip shall be bronze or other material,
which exhibits mechanical strength, electrical continuity between sections
and doesn't give rise to electrolytic or corrosive action. All coupling units
shall be the same length of threaded length of the rod.
E. Earth rods shall be a minimum length of 3 meters 3/4" inch diameter and
shall be driven into the ground using a suitable mechanical hammer. The
tops of the rods shall be flush with ground level.
F. The top of each rod electrode shall be housed in a purpose made concrete
pit to facilitate inspection. The pit shall be provided with a lid and the
assembly shall be flush with ground level.
G. Earth pits shall be provided with a waterproof seal.
H. Parallel connected earth rods shall be spaced at a horizontal distance equal
to their buried length. They shall be connected with bare stranded copper
cable unless otherwise shown on the drawings, buried not less than 750 mm
below ground level unless otherwise shown on the drawings.
I. Copper strip or stranded cable may be installed in the same trenches as
M.V/LV cables but shall be separated from all other cables and services by
a distance not less than 300mm.
J. The resistance to earth of the electrode system for power services shall not
exceed four ohms and for communication services shall not exceed half
ohm. Site testes shall be made to ascertain that the electrode system
resistance meets this requirement. If the resistance exceeds this figure the
contractor shall provide the necessary materials to reduce the system
resistance to the specified level.
5
K. A surge arrestor shall be installed between M.V earthing system and L.V
earthing system.
2.03 EARTHING CONDUCTORS
A. Earthing conductors connecting the main earthing terminal or bar and
electrode system shall be green/yellow PVC insulated, stranded copper
cable. A minimum of two earthing conductors shall be installed and
separately connected to the main earth bar with bolted test links of copper
and having a cross section equal to the main earth bar.
2.04 MAIN EARTHING TERMINAL
A. The main earthing terminal shall consist of hard drawn copper formed into
a bar having minimum dimensions as detailed in the earthing schematic.
B. Each earthing bar shall be mounted not less than 600mm above the finished
floor level and spaced by means of insulators not less than 50mm from the
fixing surface.
C. The diameter of fixing holes shall not exceed one third of earthing bar
width, where this is not possible then the connection shall be made to a
copper flag welded to the earthing bar.
D. Each connection to the main earthing terminal shall be identified with an
appropriately worded label made of durable material.
2.05 PROTECTIVE CONDUCTORS
A. Protective conductors between equipment earthing terminals or bars and the
main earthing terminal or bar shall be made with stranded copper insulated
cables as shown on the drawings. Cables shall be connected to remote end
of the equipment earthing terminals or bar separately connected to the main
earthing terminal or bar.
B. Where a number of protective conductors follow the same route these shall
be green/yellow PVC covered and installed on a cable tray and fixed with
purpose made cleats.
C. Connections between main earthing terminal of bars, equipment earthing
terminals, etc. and stranded copper cables shall be made with appropriate
compression type lug, bolt, nut and lock washers. Contact surfaces shall be
thoroughly cleaned and tinned.
D. Sockets lugs, bolts, nuts, washers, screws, rivets, clamps, cleats or other
items which come into direct contact with copper protective conductors
bars, strips, cables etc, shall be non-ferrous and manufactured from brass,
bronze or other suitable conducting material which will not cause
electrolytic or other corrosion. Where connections occur between copper
and galvanized structures, contact surfaces shall, additionally, be timed and
after completion compounded to exclude moisture. Protective conductors,
cables, strip, bars, lugs, etc, shall be installed in visible and serviceable
positions.
6
E. The joints shall be made using zinc free brazing material with a melting
point of at least 600 OC. The amount of overlap between the two strips to
be jointed shall not be less than the width of the larger conductor.
PART 3 – EXECUTION:
3.01 EXAMINATION
A. Examine conditions under which electrical earthing connections are to be
made and notify in writing of conditions detrimental to proper completion
of work. Do not proceed with work until unsatisfactory conditions have
been corrected.
3.02 INSTALLATION
A. Install electrical earthing system ad indicated in accordance with
manufacturer's instructions, requirements of applicable standards, and in
accordance with recognized industry practices to ensure that installation
complies with requirements and serves intended function.
B. Coordinate as necessary to interface installation of earthing system work
with other work.
C. Earth the electrical installation including, but not limited to, the following:
Underground distribution service equipment, electrical service system,
switchgear housings, cabinets, housings and neutrals of transformers
lighting protection system, emergency distribution systems, busway
enclosures, motor control centers, individual starters cables trays, cable
trunkings and other non-current carrying metal parts of electrical
equipment.
D. Wherever flexible metal conduit or cable are used for part of a raceway run,
provide an earthing conductor in the raceway or cable and connect to
earthings at each end of run.
E. Where pull boxes contain barriers, provide an earth lug in each section.
F. Install earthing conductors in all circuits wiring.
G. Terminate feeder and branch circuit insulated equipment earthing
conductors with earthing lug, bus, or busing.
H. Route earthing connections and conductors to earth and protective devices
in shortest and straightest paths as possible to minimize transient voltage
rises.
I. Install thermo – weld connections on clean metal contact surfaces, to ensure
electrical conductivity and circuit integrity.
J. Where expansion fittings occur, provide internal earth conductor
terminating in adjacent pulling points with earthing bushings.
K. Metallic pipe services for example, gas mains, water mains and dry risers
shall be effectively bonded to the main earthing terminal at their point of
entry. Connections shall be made to the services with purpose-made
earthing clamps.
7
L. Where there is a lightning conductor system for the building or structure, it
shall be effectively bonded to the main earthing terminal. A suitable label
shall be provided adjacent to this bonding connection at the main earthing
terminal indicating the purposed of connection.
M. Building structures shall be effectively bonded to the main earthing system
(Grid).
N. The cross-sectional area of all earthing, bonding and protective conductors
shall comply with the requirements of the IEE wiring regulations. Except
where detailed otherwise in this specification or on the drawings all
conductors for earthing shall be copper.
O. Single-core cables forming part of the earthing system shall be of stranded
copper, with green/yellow PVC.
P. Mechanical joints between aluminium and copper shall have the joint faces
lightly coated with an anti-corrosion compound before the connection is
made.
Q. Where conduits, or glands for armoured cables, terminate on switchgear,
distribution boards, starter panels or other apparatus then brass compression
washers shall be used to ensure an effective earth connection.
R. Where connections are made between sections of raceways then the
manufacturer's earth continuity links shall be installed across the joint.
Connections made between raceways. Sections crossing a building
expansion joint shall be made with a flexible copper braid
S. Sections of cable tray shall be thoroughly cleaned before overlapping and
securing with a minimum of two screwed fixings. The remote ends of the
cable tray shall be effectively bonded to the earthing system.
T. The armouring of plastic cables terminate in compression glands fitted with
purpose-made earth tags. A protective conductor shall connect the earth tag
with the apparatus earthing terminal. The earth tag shall be manufactured
from a high conductivity material compatible with the cable gland.
U. The armouring of metal sheathed cables shall be securely clamped to the
gland at the cable termination with a purpose-made bolted clamp.
A protective conductor shall be installed to connect the armour clamp or
gland fixing bolts to the apparatus terminal.
3.03 EARTH TESTS:
A. After installation of the individual earthing systems in accordance with the
above for the various parts of the works and after the whole installation has
been connected up, resistance tests shall be carried out at each sub-station
and for each earth source independently and the readings obtained officially
and recorded. Three readings shall be obtained for each sub-station relating
to the two earth paths connected individually and in parallel.
B. An Ever shed and vignoles or similar earth tester shall be used and all
results tabulated and handed to the Engineer.
8
3.04 FIELD QUANTITY CONTROL :
A. Upon completion of installation of electrical earthing, test ground
resistance tester.
B. Weld earthing conductors to underground earthing electrodes.
C. Earth electrical service system neutral at service entrance equipment to
earthing electrodes.
D. Earthing each separately –derived system neutral to:
a. Effectively earthed metallic water pipe.
b. Effectively earthed structural steel member.
c. Separate earthing electrode.
END OF SECTION 16452
PART 1 - GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including General and
Supplementary Conditions and Division-1 Specification sections, apply
to work of this section.
B. Requirements of the following Division 16 Sections apply to this Section:
1. "Basic Electrical Materials and Methods."
1.02 SUMMARY:
A. Description of Work: this section includes complete installations to earth
every source of energy and to provide protective earthing and equipotential
bonding, including but not limited to the following::
1. Transformer neutral earthing
2. Main earthing terminals or bars
3. Exposed conductive parts of electrical equipment
4. Extraneous conductive parts
5. Standby generator neutral earthing.
6. Supplementary earthing bars.
B. Related Sections: the following sections contain special requirements that
relate to this section:
1. Division 13 for "Security Systems" earthing
2. Division 14 for "Dumbwaiters," "Elevators", "Escalators", and
"Materials Handling
3. Division 15 for "Mechanical Equipment & Installation"
4. Division 16 for "Wires and Cables" for earthing system.
5. Division 16 for "Lightning Protection System".
1.03 DEFINITIONS OF TERMS
A. "Grounding" or "Ground" used in other sections or divisions of the
specification are interchangeably used as "Earthing" or "Earth".
B. Earth: conductive mass of the Earth whose electric potential at any point is
conventionally taken as zero.
2
C. Earth Electrode: conductor or group of conductors in initial contact with,
and providing electrical connection to, Earth.
D. Exposed Conductive Part: any part which can be readily touched and which
is not a live part, but which may become live under fault conditions.
E. Extraneous Conductive Part: any conductive part not forming part of the
electrical installation such as structural metalwork of a building, metallic
gas pipes, water pipes, heating tubes etc. and non-electrical apparatus
electrically connected to them i.e. radiators, cooking ranges, metal sinks etc.
and non-insulating floors and walls.
F. Protective Conductor: conductor used for some measure of protection
against electric shock and intended for connecting together any of the
following parts:
exposed conductive parts
extraneous conductive parts
earth electrode(s)
main earthing terminal or bar(s)
earthed point of the source(s)
G. Electrically Independent Earth Electrodes: earth electrodes located at such
distance from one another that maximum current likely to flow through one
of them does not significantly affect the potential of the other(s).
H. Main Earthing Terminal or Bar: the terminal or bar provided for the
connection of protective conductors, including equipotential bonding and
functional earthing conductors if any to the means of earthing.
I. Equipotential Bonding: electrical connection to put exposed and extraneous
conductive parts at a substantially equal potential.
J. Earthing Conductor: protective conductor connecting main earthing
terminal or bar of an installation to earth electrode or to other means of
earthing.
1.04 SUBMITTALS:
A. General: submit the following in accordance with Conditions of Contract
and Division 1 Specification Sections.
B. Product Data: for earth rods, connectors and connection materials, and
earthing fittings.
C. Equipment Data: prior to ordering materials, submit data for approval
including, but not limited to, manufacturer's catalogues for earth rods,
connecting clamps, earthing conductors, protective conductors, bonding
conductors, connectors and other accessories, exothermic welding kits and
tools etc., and samples of conductors as requested.
3
D. Shop and Construction Drawings: submit drawings for approval including,
but not limited to, the following:
1. Exact location of earth pits, rods and details of installation and
connections,
2. Exact routing of buried earthing conductors with indication of crosssection,
depth of laying and covering,
3. Cross sectional area and exact routing of all earthing, protective and
bonding conductors,.
4. Layout and details of earthing provisions at substations, generator
rooms, switchgear, distribution panelboards, low current rooms etc.,
indicating fittings used, insulation, plates and marking, passage and
routing of earthing conductors, conduit, sleeves, grooves, niches etc.,
giving sizes and dimensions of component parts.
E. Field Testing Organization Certificate: signed by the Contractor, certifying
that the organization performing field tests complies with the requirements
specified in Quality Assurance below.
F. Report of field tests and observations certified by the testing organization.
G. Report of field tests and observations certified by the Engineer. (All tests
shall be carried out in the presence of and be certified by the Engineer.
H. Samples: Submit sample of earthing cables and earthing accessories.
I. Calculations: submit detailed calculations verifying the earth resistance
value considering the soil conditions.
1.05 QUALITY ASSURANCE:
A. Manufacturer's Qualifications: Firms regularly engaged in the manufacture
earthing products, of types, and ratings required, and ancillary materials,
including stranded cable, copper braid and bus and bonding jumpers whose
products have been in satisfactory use in similar service for not less than 5
years.
B. Standards Compliance: Comply with requirements of applicable local
codes, IEC 61364-5 and IEE wiring regulations 16th edition pertaining to
electrical earthing system and equipment.
C. Regulations and Standards: carry out work in accordance with the
following:
1. IEC publications 364-3 and 364-4-41, Electrical Installations in
Buildings
2. BS7671:1992 Requirements for Electrical Installations (IEE Wiring
Regulations).
3. BS 7430 Earthing code of pratiace.
D. Field-Testing Organization Qualifications: to qualify for acceptance, the
independent testing organization must demonstrate, based on evaluation of
organization-submitted criteria , that it has the experience and capability to
conduct satisfactorily the testing indicated.
E. Egyptian Building codes & regulations.
4
PART 2 - PRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements,
specifications, regulations and drawings.
B. For recommended manufacturers refer to the list of recommended
manufactures.
2.02 ELECTRODES
A. Earthing system will be provided for the earthing of the entire development
including the L.V switchgears, panel boards, electrical circuits, building
structure, bonding …etc and associated equipments.
B. Earthing rods will be installed as indicated in the drawings with cable
connection to earthing equalizer/bars.
C. Earth rods shall be of circular cross-section copper bond type and as
indicated shall be jointed with purpose made couplings and a suitable
driving cap and tip shall be fitted to the rod. Couplings shall not exceed the
diameter of the rod.
D. Rod section couplings, driving cap and tip shall be bronze or other material,
which exhibits mechanical strength, electrical continuity between sections
and doesn't give rise to electrolytic or corrosive action. All coupling units
shall be the same length of threaded length of the rod.
E. Earth rods shall be a minimum length of 3 meters 3/4" inch diameter and
shall be driven into the ground using a suitable mechanical hammer. The
tops of the rods shall be flush with ground level.
F. The top of each rod electrode shall be housed in a purpose made concrete
pit to facilitate inspection. The pit shall be provided with a lid and the
assembly shall be flush with ground level.
G. Earth pits shall be provided with a waterproof seal.
H. Parallel connected earth rods shall be spaced at a horizontal distance equal
to their buried length. They shall be connected with bare stranded copper
cable unless otherwise shown on the drawings, buried not less than 750 mm
below ground level unless otherwise shown on the drawings.
I. Copper strip or stranded cable may be installed in the same trenches as
M.V/LV cables but shall be separated from all other cables and services by
a distance not less than 300mm.
J. The resistance to earth of the electrode system for power services shall not
exceed four ohms and for communication services shall not exceed half
ohm. Site testes shall be made to ascertain that the electrode system
resistance meets this requirement. If the resistance exceeds this figure the
contractor shall provide the necessary materials to reduce the system
resistance to the specified level.
5
K. A surge arrestor shall be installed between M.V earthing system and L.V
earthing system.
2.03 EARTHING CONDUCTORS
A. Earthing conductors connecting the main earthing terminal or bar and
electrode system shall be green/yellow PVC insulated, stranded copper
cable. A minimum of two earthing conductors shall be installed and
separately connected to the main earth bar with bolted test links of copper
and having a cross section equal to the main earth bar.
2.04 MAIN EARTHING TERMINAL
A. The main earthing terminal shall consist of hard drawn copper formed into
a bar having minimum dimensions as detailed in the earthing schematic.
B. Each earthing bar shall be mounted not less than 600mm above the finished
floor level and spaced by means of insulators not less than 50mm from the
fixing surface.
C. The diameter of fixing holes shall not exceed one third of earthing bar
width, where this is not possible then the connection shall be made to a
copper flag welded to the earthing bar.
D. Each connection to the main earthing terminal shall be identified with an
appropriately worded label made of durable material.
2.05 PROTECTIVE CONDUCTORS
A. Protective conductors between equipment earthing terminals or bars and the
main earthing terminal or bar shall be made with stranded copper insulated
cables as shown on the drawings. Cables shall be connected to remote end
of the equipment earthing terminals or bar separately connected to the main
earthing terminal or bar.
B. Where a number of protective conductors follow the same route these shall
be green/yellow PVC covered and installed on a cable tray and fixed with
purpose made cleats.
C. Connections between main earthing terminal of bars, equipment earthing
terminals, etc. and stranded copper cables shall be made with appropriate
compression type lug, bolt, nut and lock washers. Contact surfaces shall be
thoroughly cleaned and tinned.
D. Sockets lugs, bolts, nuts, washers, screws, rivets, clamps, cleats or other
items which come into direct contact with copper protective conductors
bars, strips, cables etc, shall be non-ferrous and manufactured from brass,
bronze or other suitable conducting material which will not cause
electrolytic or other corrosion. Where connections occur between copper
and galvanized structures, contact surfaces shall, additionally, be timed and
after completion compounded to exclude moisture. Protective conductors,
cables, strip, bars, lugs, etc, shall be installed in visible and serviceable
positions.
6
E. The joints shall be made using zinc free brazing material with a melting
point of at least 600 OC. The amount of overlap between the two strips to
be jointed shall not be less than the width of the larger conductor.
PART 3 – EXECUTION:
3.01 EXAMINATION
A. Examine conditions under which electrical earthing connections are to be
made and notify in writing of conditions detrimental to proper completion
of work. Do not proceed with work until unsatisfactory conditions have
been corrected.
3.02 INSTALLATION
A. Install electrical earthing system ad indicated in accordance with
manufacturer's instructions, requirements of applicable standards, and in
accordance with recognized industry practices to ensure that installation
complies with requirements and serves intended function.
B. Coordinate as necessary to interface installation of earthing system work
with other work.
C. Earth the electrical installation including, but not limited to, the following:
Underground distribution service equipment, electrical service system,
switchgear housings, cabinets, housings and neutrals of transformers
lighting protection system, emergency distribution systems, busway
enclosures, motor control centers, individual starters cables trays, cable
trunkings and other non-current carrying metal parts of electrical
equipment.
D. Wherever flexible metal conduit or cable are used for part of a raceway run,
provide an earthing conductor in the raceway or cable and connect to
earthings at each end of run.
E. Where pull boxes contain barriers, provide an earth lug in each section.
F. Install earthing conductors in all circuits wiring.
G. Terminate feeder and branch circuit insulated equipment earthing
conductors with earthing lug, bus, or busing.
H. Route earthing connections and conductors to earth and protective devices
in shortest and straightest paths as possible to minimize transient voltage
rises.
I. Install thermo – weld connections on clean metal contact surfaces, to ensure
electrical conductivity and circuit integrity.
J. Where expansion fittings occur, provide internal earth conductor
terminating in adjacent pulling points with earthing bushings.
K. Metallic pipe services for example, gas mains, water mains and dry risers
shall be effectively bonded to the main earthing terminal at their point of
entry. Connections shall be made to the services with purpose-made
earthing clamps.
7
L. Where there is a lightning conductor system for the building or structure, it
shall be effectively bonded to the main earthing terminal. A suitable label
shall be provided adjacent to this bonding connection at the main earthing
terminal indicating the purposed of connection.
M. Building structures shall be effectively bonded to the main earthing system
(Grid).
N. The cross-sectional area of all earthing, bonding and protective conductors
shall comply with the requirements of the IEE wiring regulations. Except
where detailed otherwise in this specification or on the drawings all
conductors for earthing shall be copper.
O. Single-core cables forming part of the earthing system shall be of stranded
copper, with green/yellow PVC.
P. Mechanical joints between aluminium and copper shall have the joint faces
lightly coated with an anti-corrosion compound before the connection is
made.
Q. Where conduits, or glands for armoured cables, terminate on switchgear,
distribution boards, starter panels or other apparatus then brass compression
washers shall be used to ensure an effective earth connection.
R. Where connections are made between sections of raceways then the
manufacturer's earth continuity links shall be installed across the joint.
Connections made between raceways. Sections crossing a building
expansion joint shall be made with a flexible copper braid
S. Sections of cable tray shall be thoroughly cleaned before overlapping and
securing with a minimum of two screwed fixings. The remote ends of the
cable tray shall be effectively bonded to the earthing system.
T. The armouring of plastic cables terminate in compression glands fitted with
purpose-made earth tags. A protective conductor shall connect the earth tag
with the apparatus earthing terminal. The earth tag shall be manufactured
from a high conductivity material compatible with the cable gland.
U. The armouring of metal sheathed cables shall be securely clamped to the
gland at the cable termination with a purpose-made bolted clamp.
A protective conductor shall be installed to connect the armour clamp or
gland fixing bolts to the apparatus terminal.
3.03 EARTH TESTS:
A. After installation of the individual earthing systems in accordance with the
above for the various parts of the works and after the whole installation has
been connected up, resistance tests shall be carried out at each sub-station
and for each earth source independently and the readings obtained officially
and recorded. Three readings shall be obtained for each sub-station relating
to the two earth paths connected individually and in parallel.
B. An Ever shed and vignoles or similar earth tester shall be used and all
results tabulated and handed to the Engineer.
8
3.04 FIELD QUANTITY CONTROL :
A. Upon completion of installation of electrical earthing, test ground
resistance tester.
B. Weld earthing conductors to underground earthing electrodes.
C. Earth electrical service system neutral at service entrance equipment to
earthing electrodes.
D. Earthing each separately –derived system neutral to:
a. Effectively earthed metallic water pipe.
b. Effectively earthed structural steel member.
c. Separate earthing electrode.
END OF SECTION 16452
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