This standard is based on “Conduits for Electrical Installations - Specification Part 1: General Requirements” (IEC 614-1 (1978).
1 Subject Content and Application Scope
This standard specifies General Technical Requirements for conduits in electric installation (hereafter referred to as simply "conduit") and corresponding test methods, inspection rules, etc.
This standard is used to protect conductor or cable and conduit which has body forming circular or rectangular cross section in electric installation under 1000 V. But cement asbestos pipe, prefabricated concrete conduit block and wire groove etc. are excluded.
2 Normative References
GB/T 2951.38 Test Method on Electric Wires or Cables under Termite Conditions
GB 775 Insulator Test Methods
GB 2423.24 Basic Environmental Testing Procedures for Electric and Electronic Products Sa: Test Methods of Simulating Solar Radiation on the Ground.
GB 2828 Sampling Procedures and Tables for Lot-by-lot Inspection by Attributes (apply to inspection of successive lots or batches)
GB 2829 Sampling Procedures and Tables for Periodic Inspection by Attributes (apply to inspection of process stability)
3 Terms
3.1 Conduit
A part of a closed wiring system of circular or a non-circular cross-section for conductors and/or cables in electrical installations, allowing them to be drawn in and/or replaced.
Conduits should be sufficiently closed-jointed so that the conductors can only be drawn in and not inserted to its laterally side.
3.2 Plain Conduit
A conduit in which the profile is even in the longitudinal section.
3.3 Corrugated Conduit
A conduit in which the profile is even in the corrugation section.
3.4 Threadable Conduit
A plain conduit, the ends of which carry screw threads for connection or on which a thread can be cut manually.
3.5 Non-threadable Conduit
A conduit suitable for connection by means other than screw thread.
3.6 Rigid Conduit
A conduit which can only be bent with the help of a mechanical aid with or without special treatment.
3.7 Pliable Conduit
A conduit which can be bent by hand with reasonable force, but without other assistance.
3.8 Self-Recovering Conduit
A pliable conduit which deforms when a transverse force is applied for a short time, and returns close to its original shape within a further short time after removal of the force.
3.9 Flexible Conduit
A conduit which can be bent by hand with a relatively small force, but without other assistance, and which is intended to flex frequently throughout its life.
3.10 Metal Conduit
It refers to the conduit made of metallic material.
3.11 Insulating Conduit
It refers to the conduit made of insulating material, without any conductive part (without internal metal lining or external metal mesh or metal coating).
3.12 Composite Conduit
A conduit comprising both conductive and insulating materials.
3.13 Non-Flame Propagating Conduit
A conduit which is liable to catch fire as a result of applied flame, in which the flame does not propagate, and which extinguishes itself within a limited time after the flame is removed
3.14 Wall Thickness
The difference between the outside and the inside diameter, divided by two.
3.15 Material Thickness
For a corrugated conduit, the average thickness of material measured at any point along the shape of one corrugation.
3.16 External Influences
The presence of water, oil or building materials, low and high temperatures, corrosive or polluting substances, and solar radiation.
4 Classification
4.1 Classification based on materials
a Metal conduit
b Insulating conduit
c Composite conduit
4.2 According to method of connection
4.2.1 Threadable conduits
A Plain conduits
4.2.2 Non-threadable conduits
a Plain conduits;
b Corrugation conduit.
4.3 According to mechanical properties
a Conduits for very light mechanical stresses;
b Conduits for relatively light mechanical stresses;
c Conduits for medium mechanical stresses;
d Conduits for relatively heavy mechanical stresses;
e Conduits for very heavy mechanical stresses.
4.4 According to suitability for bending
a Rigid conduit
b Pliable conduits
c Self-recovering conduits;
d Flexible conduit.
4.5 According to temperatures, given in the following table:
Table 1
Temperature classification Generally, temperature not less than Permanent application temperature range
In storage and transportation In usage and installation
-45 -45 -15 -15-+60
-25 -25 -15 -15-+60
-5 -5 -5 -5-+60
+90 -5 -5 -5-+601)
+90/-25 -25 -15 -15-+601)
Note: 1) These types, for use in prefabricated concrete, will temporarily withstand temperature up to +90℃.
4.6 According to resistance to flame-propagation
a Non-flame propagating conduits;
b Flame propagating conduits;
4.7 According to electrical characteristics:
a Conduits without electrical continuity;
b Conduits with electrical continuity;
c Conduits without electrical insulating characteristics;
d Conduits with electrical insulating characteristics;
4.8 According to resistance to external influences
4.8.1 Protection against ingress of water
a Conduits giving no protection;
b Conduits giving protection against spraying water;
c Conduits giving protection against splashing water;
d Conduits giving protection against water jets;
e Conduits giving protection against heavy seas;
f Conduits giving protection against immersion;
g Conduits giving protection against submersion.
4.8.2 Resistance to corrosive or polluting substances
4.8.2.1 Conduits with the same protection on the outside and the inside
a Conduits with low protection;
b Conduits with medium protection;
c Conduits with high protection;
4.8.2.2 Conduits with greater protection on the outside than the inside
a Conduits with medium protection outside and low protection inside;
b Conduits with high protection outside and low protection inside;
c Conduits with high protection outside and medium protection inside;
4.8.3 Resistance to solar radiation:
4.8.3.1 Conduits without protection against solar radiation;
4.8.3.2 Conduits with protection against solar radiation;
a Conduits with low protection against radiation;
b Conduits with medium protection against radiation;
c Conduits with high protection against radiation.
4.8.4 Resistance to damage by rats, termite and other objects
a Conduits giving protection against vermin and rats solid objects greater than 2.5mm;
b Conduits giving protection against termite and solid objects greater than 1mm;
c Conduits giving no protection against termite, vermin, rats and solid objects.
4.8.5 Protection against dust
4.8.5.1 Conduits giving protection against dust.
4.8.5.1 Conduits giving no protection against dust.
5 Marking
5.1 Conduits shall be marked with:
a The name of the manufacturer or responsible vendor, trade mark, or other identifying symbol;
b A classification code in accordance with clause A.1 of annex A;
c Any other mark or symbol required by the relevant section of part 2 of this standard.
Conduits may also be marked with an additional classification code in accordance with clause A.2 of annex A.
5.2 Marking of conduits shall be repeated at regular intervals, preferably of 1 m but no longer than 3m. Rigid conduits shall be marked at least once on each manufacturing length, preferably 50 mm from one end.
5.3 Pliable or flexible conduit supplied in coils shall, in addition, have an attached label marked with the maker’s name or trade mark immediately followed by a classification code.
Note: It's allowed to use other methods for marking in corrugation conduit except for marking on its own account; but the marking shall meet Article 5.
5.4 Marking shall be durable and easily legible.
5.5 Marking may be applied by moulding, stamping, printing, adhesive label, or water slide transfers.
6 Dimensions (the "dimensions" in this standard refers to nominal size)
6.1 The outside diameters and threads shall comply with national standard "Conduits for Electrical Purposes-Outside Diameters of Conduits for Electrical Installations and Threads for Conduits and Fittings".
6.2 Other dimensions of conduits, such as inside diameter, shall comply with technical requirements specified in special requirements Standard.
6.3 Generally, factory length of rigid conduit is 4m; other specifications should be negotiated by both parties. The specified length tolerance of metal conduit is ± 10mm; rigid insulating conduit ± 1.5mm.
7 Construction
7.1 The inside and outside surfaces of conduits shall be reasonably free from burrs, flash and similar defects; in addition, the edges over which the conductors or cables are likely to be drawn, shall not damage these conductors or cables.
7.2 A slight burr resulting from the method of manufacturing is not taken into account if it is not likely to damage insulated conductors.
7.3 The wall thickness of conduit shall be uniform, the uniformity of conduit wall shall comply with type (1) after construction checking in Article 13.4 C .
Contents
1 Subject Content and Application Scope
2 Normative References
3 Terms
4 Classification
5 Marking
6 Dimensions (the "dimensions" in this standard refers to nominal size)
7 Construction
8 Mechanical Properties
9 Resistance to Heat
10 Resistance to Burning
11 Electrical Performance
12 External Influences
13 Test Methods
14 Test Rules
15 Packaging, packaging marks, transportation and storage.
Additional Description
