Is this code still valid for use?

No, IS 9537 (Part 2) has been officially replaced by IS 3480:2023. This code should only be used for reference on older installations.

What are the standard sizes covered in this code?

The code specifies nominal sizes ranging from 16 mm to 63 mm (Table 1).

What is the main test to check the durability of the flexible conduit?

The resistance to flexing test (Appendix A), which requires the conduit to withstand 5000 flexing cycles without breaking or uncoiling.

How is the compression strength classified?

It's classified based on the force it can withstand. For example, 'Class 2 Light' must resist 320 N and 'Class 3 Medium' must resist 750 N (Table 2).

IS 9537 Part 2

: 1981

Conduits for electrical installations - Part 2: Flexible steel conduits

CurrentFrequently UsedSpecificationBIMMEP · Electrical Installations

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This standard specifies the requirements for plain (uncovered), flexible steel conduits intended for the protection of cables in electrical installations. It covers material, construction, dimensions, mechanical strength (compression and flexing), and testing procedures.

Specifies requirements for flexible steel conduits used for the protection of electrical wiring installations.

Quick Reference Values

Range of nominal sizes16 mm to 63 mm

Minimum compression force (Class 2 Light)320 N

Minimum compression force (Class 3 Medium)750 N

Number of cycles for flexing test5000 cycles

Tolerance on internal diameter (for 20mm size)+0.4 / -0.0 mm

Maximum external diameter (for 20mm size)22.5 mm

Practical Notes

CRITICAL: This standard has been superseded and withdrawn. For all new projects, refer to IS 3480:2023 'Flexible Steel Conduits for Cable Management'.

Select the conduit classification (Light, Medium, etc.) based on the anticipated mechanical stress and protection level required for the installation area.

Ensure proper termination using glands and accessories to maintain mechanical integrity and electrical continuity of the system.