R-1 — لوائح التركيبات الكهربائية
6 التأريض وحماية تسرب الأرض
الصفحة 20 في الوثيقة الأصلية
عرض PDFملخص التأريض وقواطع التسرب (RCCB)
SECTION 6
EARTHING AND EARTH LEAKAGE PROTECTION
601 Every consumer, who is provided with a separate service intake by the Ministry of Electricity and Water,
shall provide an adequate earth electrode immediately adjacent to the service intake. The earth electrode shall be
housed in an approved handhole which shall be fitted with a heavy duty inspection cover. The earth electrode shall
comprise of a copper clad rod of 16 mm. diameter driven to a minimum depth of 3 metres. The radial copper
coating shall be minimum 250 microns with 99.9% copper content. The top of the electrode shall be provided with
a corrosion resistant terminal connection. The connection of the earthing lead to the earth electrode shall be
soundly made and electrically and mechanically satisfactory and suitably labeled.
602 The overall resistance between any point on the earth installation and the general mass of the earth shall be
less than 2.0 ohms.
NOTE - In order to achieve the above value in areas of high soil resistivity It may be necessary to install
more than one earth electrode.
603 Every consumer's electrical installation shall be provided with an earthing terminal which shall be located
adjacent to the consumers supply intake and within his boundaries . Throughout the consumers electrical
installation, an earth continuity conductor of adequate size and coloured green/yellow shall be provided and
connected to the earthing terminal. The cross sectional area of copper earth continuity conductors shall be in
accordance with the appropriate table in Section 15. In mechanical plant rooms and other similar locations flat
copper tape may be employed in place of stranded conductors.
604 The earthing terminal of every socket outlet shall be connected to the earth continuity conductor of the final
circuit. Where the earth continuity conductor is formed by conduit or trunking, the earthing terminal of each
socket outlet shall be connected by a conductor of adequate size to an earthing terminal incorporated in the
associated box or other enclosure.
605 At every lighting point an earth terminal shall be provided and connected to the earth continuity conductor
of the final circuit. An earth terminal, connected to the earth continuity conductor of the final circuit, shall be
provided at every lighting switch position unless this takes the form of an earthed metal box having a means of
fixing the switch plate in reliable electrical contact with the box.
606 Where wiring is enclosed in a continuous system of metallic conduit or trunking, such conduit or trunking
may be employed as an earth continuity conductor provided all joints are electrically sound and the specified earth
continuity resistances can be obtained and maintained. The steel armouring of cables may also be employed as a
near the continuity conductor provided the specified earth continuity resistances can be obtained and maintained.
607 Where steel conduit, trunking and/or cable sheath, armouring, form a part or whole of the earth continuity
conductor, the resistance of any point in the earth continuity system to the main earth electrode shall not exceed
0.5 ohms including the connection to the main earth electrode. Where the earth continuity conductor is composed
entirely of copper then they said resistance shall not exceed 1ohm.
608 All metal work of wiring systems (other than current carrying parts) including cable sheaths and armour,
conduits, ducts, trunking and boxes shall be connected to the appropriate earth continuity conductors. The
exposed metal work of all domestic apparatus and equipment like window air conditioning units, washing
machines, refrigerators and the like shall also be connected to appropriate earth continuity conductors. The
exposed metal work of motors, starters and other non-domestic equipment like package and central air
conditioning units, air handling equipment, laundry, lift machinery and the like, shall also be effectively connected
to a main earth continuity conductor which is directly connected at both ends to earth electrodes. The connection
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from each piece of equipment to the main earth continuity conductor shall be by separate branch earth continuity
conductors of adequate sizes and in accordance with the appropriate table in Section 15. Branch earth continuity
conductors shall be connected to main earth continuity conduc tors by permanently soldered, fusion welded o r
mechanically clamped joints that will not be accidentally or unwittingly broken. The series method of earthing one
piece of apparatus to another sh all not be permitted except in the case of socket outlets connected to a ring circuit
and lighting points.
609 The consume rs earthing terminal mentioned in clause 603 shall be connected by an earthing lead of
appropriate size to the earth electrode loca ted adjacent to the service intake. The main earthing lead from the
consumer earthing terminal to the earth electrode shall not be run through steel or other conduit or duct of magnetic
material, but shall be protected from damage by suitable sheathing which shall not completely encircle the earth
conductor, if the sheathing is of steel or other magnetic materials. No earthing lead run separately shall be smaller
than 6 sq.mm. The size of earthing leads shall be in accordance with the appropriate table in Section. 15.
610 Every consumer's installation shall in addition to the foregoing be equipped with earth leakage protection
by one or more current operated earth leakage circuit breakers to afford the protection stipulated in Clause
611 to 613.
611 The following degree of protection against earth leakage shall be provided throughout the electrical
installation.
Maximum 10 mA trip rating - for under-water lighting.
Maximum 30 mA trip rating - all socket outlets and domestic apparatus.
Maximum 300 mA trip rating - lights
Preferably 300 mA and maximum 500 mA trip rating - all other apparatus and equipment such as A/C
plants, lifts, pumps, etc.
EXCEPTION: 1. Where an immediate disconnection of the electricity supply will cause difficulties to
consummers, the M.E.W. may permit omission of earth leakage circuit breakers
provided in each case a separate approval is obtained and the portion of the installation
so exempted is provided with an audio-visual alarm indicator.
2. For motors driving fire pumps, the provision of current operated earth leakage
circuit breakers will not be permitted and an audio-visual alarm indicator shall be
provided.
3. For motors over 15 H.P. earth leakage protection shall be provided individually for
each motor and a common earth leakage protection for a group of motors will not be
permitted.
612 In multi-occupancy buildings and other similar locations the ope ration of any current operated earth leakage
circuit breaker shall not interrupt the electricity supply from any other consumer in the same premises.
613 The neutral conductor shall not be earthed anywhere within the consumers premises.
614 Throughout the low voltage electrical installation the earthing system shall be separated and divorced
from the earthing system of 11 KV or higher voltage systems.
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EARTHING AND EARTH LEAKAGE PROTECTION
601 Every consumer, who is provided with a separate service intake by the Ministry of Electricity and Water,
shall provide an adequate earth electrode immediately adjacent to the service intake. The earth electrode shall be
housed in an approved handhole which shall be fitted with a heavy duty inspection cover. The earth electrode shall
comprise of a copper clad rod of 16 mm. diameter driven to a minimum depth of 3 metres. The radial copper
coating shall be minimum 250 microns with 99.9% copper content. The top of the electrode shall be provided with
a corrosion resistant terminal connection. The connection of the earthing lead to the earth electrode shall be
soundly made and electrically and mechanically satisfactory and suitably labeled.
602 The overall resistance between any point on the earth installation and the general mass of the earth shall be
less than 2.0 ohms.
NOTE - In order to achieve the above value in areas of high soil resistivity It may be necessary to install
more than one earth electrode.
603 Every consumer's electrical installation shall be provided with an earthing terminal which shall be located
adjacent to the consumers supply intake and within his boundaries . Throughout the consumers electrical
installation, an earth continuity conductor of adequate size and coloured green/yellow shall be provided and
connected to the earthing terminal. The cross sectional area of copper earth continuity conductors shall be in
accordance with the appropriate table in Section 15. In mechanical plant rooms and other similar locations flat
copper tape may be employed in place of stranded conductors.
604 The earthing terminal of every socket outlet shall be connected to the earth continuity conductor of the final
circuit. Where the earth continuity conductor is formed by conduit or trunking, the earthing terminal of each
socket outlet shall be connected by a conductor of adequate size to an earthing terminal incorporated in the
associated box or other enclosure.
605 At every lighting point an earth terminal shall be provided and connected to the earth continuity conductor
of the final circuit. An earth terminal, connected to the earth continuity conductor of the final circuit, shall be
provided at every lighting switch position unless this takes the form of an earthed metal box having a means of
fixing the switch plate in reliable electrical contact with the box.
606 Where wiring is enclosed in a continuous system of metallic conduit or trunking, such conduit or trunking
may be employed as an earth continuity conductor provided all joints are electrically sound and the specified earth
continuity resistances can be obtained and maintained. The steel armouring of cables may also be employed as a
near the continuity conductor provided the specified earth continuity resistances can be obtained and maintained.
607 Where steel conduit, trunking and/or cable sheath, armouring, form a part or whole of the earth continuity
conductor, the resistance of any point in the earth continuity system to the main earth electrode shall not exceed
0.5 ohms including the connection to the main earth electrode. Where the earth continuity conductor is composed
entirely of copper then they said resistance shall not exceed 1ohm.
608 All metal work of wiring systems (other than current carrying parts) including cable sheaths and armour,
conduits, ducts, trunking and boxes shall be connected to the appropriate earth continuity conductors. The
exposed metal work of all domestic apparatus and equipment like window air conditioning units, washing
machines, refrigerators and the like shall also be connected to appropriate earth continuity conductors. The
exposed metal work of motors, starters and other non-domestic equipment like package and central air
conditioning units, air handling equipment, laundry, lift machinery and the like, shall also be effectively connected
to a main earth continuity conductor which is directly connected at both ends to earth electrodes. The connection
20
from each piece of equipment to the main earth continuity conductor shall be by separate branch earth continuity
conductors of adequate sizes and in accordance with the appropriate table in Section 15. Branch earth continuity
conductors shall be connected to main earth continuity conduc tors by permanently soldered, fusion welded o r
mechanically clamped joints that will not be accidentally or unwittingly broken. The series method of earthing one
piece of apparatus to another sh all not be permitted except in the case of socket outlets connected to a ring circuit
and lighting points.
609 The consume rs earthing terminal mentioned in clause 603 shall be connected by an earthing lead of
appropriate size to the earth electrode loca ted adjacent to the service intake. The main earthing lead from the
consumer earthing terminal to the earth electrode shall not be run through steel or other conduit or duct of magnetic
material, but shall be protected from damage by suitable sheathing which shall not completely encircle the earth
conductor, if the sheathing is of steel or other magnetic materials. No earthing lead run separately shall be smaller
than 6 sq.mm. The size of earthing leads shall be in accordance with the appropriate table in Section. 15.
610 Every consumer's installation shall in addition to the foregoing be equipped with earth leakage protection
by one or more current operated earth leakage circuit breakers to afford the protection stipulated in Clause
611 to 613.
611 The following degree of protection against earth leakage shall be provided throughout the electrical
installation.
Maximum 10 mA trip rating - for under-water lighting.
Maximum 30 mA trip rating - all socket outlets and domestic apparatus.
Maximum 300 mA trip rating - lights
Preferably 300 mA and maximum 500 mA trip rating - all other apparatus and equipment such as A/C
plants, lifts, pumps, etc.
EXCEPTION: 1. Where an immediate disconnection of the electricity supply will cause difficulties to
consummers, the M.E.W. may permit omission of earth leakage circuit breakers
provided in each case a separate approval is obtained and the portion of the installation
so exempted is provided with an audio-visual alarm indicator.
2. For motors driving fire pumps, the provision of current operated earth leakage
circuit breakers will not be permitted and an audio-visual alarm indicator shall be
provided.
3. For motors over 15 H.P. earth leakage protection shall be provided individually for
each motor and a common earth leakage protection for a group of motors will not be
permitted.
612 In multi-occupancy buildings and other similar locations the ope ration of any current operated earth leakage
circuit breaker shall not interrupt the electricity supply from any other consumer in the same premises.
613 The neutral conductor shall not be earthed anywhere within the consumers premises.
614 Throughout the low voltage electrical installation the earthing system shall be separated and divorced
from the earthing system of 11 KV or higher voltage systems.
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