R-1 — لوائح التركيبات الكهربائية
725 القنوات غير المعدنية الصلبة
الصفحة 27 في الوثيقة الأصلية
عرض PDF725 RIGID NON-METALLIC CONDUITS
725-1 Rigid non-metallic conduits may be employed in general electrical installations provided it is made
from polyvinyl chloride or equivalent material that has been certified as suitable for use at ambient
temperatures up to 55°C. Additionally the material shall not soften or suf fer any structural degradation at a
temperature of 85°C, shall be non-hygroscopic, and self-extinguishing type.
NOTE - Rigid non-metallic conduits shall not be used at locations where they will be subjected to
mechanical damage.
725-2 The inside and outside surfaces of non-metallic conduits shall be smooth and free from burrs and similar
defects. The interior and ends of conduit fittings shall have no sharp edges and corners, shall be smooth and
well rounded to permit easy drawing in of cable and prevent any damages to cable insulation.
725-3 The entries of non -metallic conduit fittings shall be so designed that a reliable water tight joint can be
made between the conduit and fittings. Vinyl cement shall be used to make all joints. A vinyl solvent shall be
used for permanent joints and a cement of the type that shall continue to remain in a sticky conditi on shall be
used for expansion couplers.
725-4 Rigid non-metallic conduits shall be so constructed that it will be possible to bend the conduit easily
with the aid of bending spring and all conduits and conduit fittings shall be of the unthreaded type.
725-5 The minimum size of rigid non-metallic conduit used for general electrical installation shall be
16mm diameter. Other sizes of rigid non-metallic conduits shall be of the following diameters:
20mm, 25mm, 32mm, 38mm, and 50mm.
725-6 The number of single core PVC insulated non -sheathed cables run in one conduit shall be such that it
permits 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 Sect ion 1 5. 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.
NOTE- Where a number of cables are bunched in one conduit, the current carrying capacity of the cables shall
be reduced by using the stipulated grouping factor. For full details refer to Section 15.
725-7 A separate insulated earth wire shall be drawn into all rigid non-metallic conduits.
725-8 Rigid non-metallic conduits shall be installed generally in accordance with the requirements set out for
metallic conduits. Additionally the method of supporting rigid non -metallic conduit shall allow for the
longitudinal expansion and contraction of the conduits.
725-9 Where a lighting fitting is suspended from a non -metallic conduit box, care shall be taken to ensure
that the temperature of the box does not exceed th e permitted safe temperature of the material and is fitted with
screwed metal insert clips. The mass suspended from the box shall not exceed 2 kgs.
725-1 Rigid non-metallic conduits may be employed in general electrical installations provided it is made
from polyvinyl chloride or equivalent material that has been certified as suitable for use at ambient
temperatures up to 55°C. Additionally the material shall not soften or suf fer any structural degradation at a
temperature of 85°C, shall be non-hygroscopic, and self-extinguishing type.
NOTE - Rigid non-metallic conduits shall not be used at locations where they will be subjected to
mechanical damage.
725-2 The inside and outside surfaces of non-metallic conduits shall be smooth and free from burrs and similar
defects. The interior and ends of conduit fittings shall have no sharp edges and corners, shall be smooth and
well rounded to permit easy drawing in of cable and prevent any damages to cable insulation.
725-3 The entries of non -metallic conduit fittings shall be so designed that a reliable water tight joint can be
made between the conduit and fittings. Vinyl cement shall be used to make all joints. A vinyl solvent shall be
used for permanent joints and a cement of the type that shall continue to remain in a sticky conditi on shall be
used for expansion couplers.
725-4 Rigid non-metallic conduits shall be so constructed that it will be possible to bend the conduit easily
with the aid of bending spring and all conduits and conduit fittings shall be of the unthreaded type.
725-5 The minimum size of rigid non-metallic conduit used for general electrical installation shall be
16mm diameter. Other sizes of rigid non-metallic conduits shall be of the following diameters:
20mm, 25mm, 32mm, 38mm, and 50mm.
725-6 The number of single core PVC insulated non -sheathed cables run in one conduit shall be such that it
permits 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 Sect ion 1 5. 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.
NOTE- Where a number of cables are bunched in one conduit, the current carrying capacity of the cables shall
be reduced by using the stipulated grouping factor. For full details refer to Section 15.
725-7 A separate insulated earth wire shall be drawn into all rigid non-metallic conduits.
725-8 Rigid non-metallic conduits shall be installed generally in accordance with the requirements set out for
metallic conduits. Additionally the method of supporting rigid non -metallic conduit shall allow for the
longitudinal expansion and contraction of the conduits.
725-9 Where a lighting fitting is suspended from a non -metallic conduit box, care shall be taken to ensure
that the temperature of the box does not exceed th e permitted safe temperature of the material and is fitted with
screwed metal insert clips. The mass suspended from the box shall not exceed 2 kgs.