R-1 — لوائح التركيبات الكهربائية
720 القنوات المعدنية الصلبة
الصفحة 26 في الوثيقة الأصلية
عرض PDF720 RIGID METALLIC CONDUITS
720-1 The use of rigid metallic conduits shall be permitted for general electrical installation provided that it is
from heavy gauge steel and hot -dip galvanized inside and outside. Black enameled steel conduits shall not be used
for electrical installations. All metallic conduits shall be screwed type.
720-2 The metallic conduit and its accessories shall form a continuous metallic sheath of adequate strength
surrounding the cables throughout the length of the conduit.
720-3 Metallic conduits shall not be run under floor tiles of buildings.
720-4 The bores of all conduits shall be smooth and free from projections and/or sharp edges which may injure
the wires or prevent them being drawn in. The internal edges of the ends of all lengths of conduit shall be radiused
or chamfered before assembling into position.
720-5 All runs of conduit shall be assembled complete with all necessary accessori es and the whole firmly
attached to the structure of the building before any wires are drawn in. All wires shall be drawn through the
covers of inspection and other fittings installed for the purpose.
720-6 All threads, vice marks, tool marks and breaks in the protective coating on metallic conduit and/or
conduit fittings shall be painted with a steel preserving paint immediately after erection.
720-7 No run of conduit shall exceed 10 meters between adjacent draw-in points. nor shall contain more than two
right angle bends, set or other deviation from the straight line.
720-8 Inspection couplings or long th rough draw-in boxes shall be used where necessary in straight runs of
conduits for drawn -in purposes and shall be placed so that cables can be inspected and if necessary
withdrawn throughout the life of installation.
720-9 Where conduit and/or conduit fittings are attached to switches, distribution boards, boxes or other
equipment, smooth bore male brass bushes and flanged couplings shall be used.
720-10 Circular or hexagonal heavy locknuts shall be used at all positions where running joints are
required and great care shall be taken to see that they seat firmly and evenly into mating faces of couplings or
other adjacent accessories.
720-11 Where exposed to water. rain or weather, all covers shall be arranged or fitted with machined joints
and/or fitted with durable gaskets such that water cannot get inside.
720-12 All runs of conduits shall be truly vertical or horizontal except where the architectural features of the
building demand otherwise.
720-13 Except where provision is made for fastening a box or other conduit fitting directly to the structure
of the building and such fastening is made, conduit shall be saddled to the structure of the building within 15 ems.
of each terminal box, angle box, bend or other conduit fitting and at intervals not greater than 1.5 m. Couplings
and through type drawing boxes shall be counted as part of a straight run of conduit.
720-14 All boxes, bends and other accessories shall be of the same material as the conduit and shall have the
same protective coatings. Grey cast iron boxes etc. may be used with metallic conduit, but shall be finished in
the same manner as the conduit to which they are directly attached.
720-15 The number of single core PVC insulated non-sheathed cables run in metallic conduit shall be such as to
permit easy drawing of the cables. The actual number of cables drawn into any conduit shall not be greater than the
number given in the appropriate table in Section 15. Where different sizes of cables are drawn into a conduit, the
number and sizes of cables installed shall be selected in accordance with the method detailed in Section 12.
720-16 Metallic conduits system need not be provided with a separate insulated earth wire and the conduit
itself may be considered as the earthing system provided all joints shall be made mechanically and electrically
continuous.
26
720-17 The minimum size of metallic conduit that may be used in electrical installations shall be 16 mm
diameter. Other sizes of conduits shall be limited to the following diameters:
20 mm, 25 mm, 32 mm, 38 mm and 50 mm.
720-1 The use of rigid metallic conduits shall be permitted for general electrical installation provided that it is
from heavy gauge steel and hot -dip galvanized inside and outside. Black enameled steel conduits shall not be used
for electrical installations. All metallic conduits shall be screwed type.
720-2 The metallic conduit and its accessories shall form a continuous metallic sheath of adequate strength
surrounding the cables throughout the length of the conduit.
720-3 Metallic conduits shall not be run under floor tiles of buildings.
720-4 The bores of all conduits shall be smooth and free from projections and/or sharp edges which may injure
the wires or prevent them being drawn in. The internal edges of the ends of all lengths of conduit shall be radiused
or chamfered before assembling into position.
720-5 All runs of conduit shall be assembled complete with all necessary accessori es and the whole firmly
attached to the structure of the building before any wires are drawn in. All wires shall be drawn through the
covers of inspection and other fittings installed for the purpose.
720-6 All threads, vice marks, tool marks and breaks in the protective coating on metallic conduit and/or
conduit fittings shall be painted with a steel preserving paint immediately after erection.
720-7 No run of conduit shall exceed 10 meters between adjacent draw-in points. nor shall contain more than two
right angle bends, set or other deviation from the straight line.
720-8 Inspection couplings or long th rough draw-in boxes shall be used where necessary in straight runs of
conduits for drawn -in purposes and shall be placed so that cables can be inspected and if necessary
withdrawn throughout the life of installation.
720-9 Where conduit and/or conduit fittings are attached to switches, distribution boards, boxes or other
equipment, smooth bore male brass bushes and flanged couplings shall be used.
720-10 Circular or hexagonal heavy locknuts shall be used at all positions where running joints are
required and great care shall be taken to see that they seat firmly and evenly into mating faces of couplings or
other adjacent accessories.
720-11 Where exposed to water. rain or weather, all covers shall be arranged or fitted with machined joints
and/or fitted with durable gaskets such that water cannot get inside.
720-12 All runs of conduits shall be truly vertical or horizontal except where the architectural features of the
building demand otherwise.
720-13 Except where provision is made for fastening a box or other conduit fitting directly to the structure
of the building and such fastening is made, conduit shall be saddled to the structure of the building within 15 ems.
of each terminal box, angle box, bend or other conduit fitting and at intervals not greater than 1.5 m. Couplings
and through type drawing boxes shall be counted as part of a straight run of conduit.
720-14 All boxes, bends and other accessories shall be of the same material as the conduit and shall have the
same protective coatings. Grey cast iron boxes etc. may be used with metallic conduit, but shall be finished in
the same manner as the conduit to which they are directly attached.
720-15 The number of single core PVC insulated non-sheathed cables run in metallic conduit shall be such as to
permit easy drawing of the cables. The actual number of cables drawn into any conduit shall not be greater than the
number given in the appropriate table in Section 15. Where different sizes of cables are drawn into a conduit, the
number and sizes of cables installed shall be selected in accordance with the method detailed in Section 12.
720-16 Metallic conduits system need not be provided with a separate insulated earth wire and the conduit
itself may be considered as the earthing system provided all joints shall be made mechanically and electrically
continuous.
26
720-17 The minimum size of metallic conduit that may be used in electrical installations shall be 16 mm
diameter. Other sizes of conduits shall be limited to the following diameters:
20 mm, 25 mm, 32 mm, 38 mm and 50 mm.