A complete guide to IS 13573 — the Bureau of Indian Standards specification for heat shrink cable accessories. Covers scope, test requirements, voltage classes, differences from IEC 60502, and how to verify a manufacturer's IS 13573 certification before procurement.

Why IS 13573 Matters for Every Indian Power Project

If you are specifying, procuring or approving heat shrink cable accessories for an Indian power project — whether for a state utility, a railway electrification contract, a solar farm or an industrial substation — one standard number appears on every approved-vendor list and tender document: IS 13573.

Yet in most engineering teams, IS 13573 is referenced by number alone. Few engineers have read the actual standard, fewer still know what specific tests it mandates, and procurement teams frequently accept "IS 13573 compliant" claims from suppliers without any way to verify them.

This guide explains what IS 13573 requires, how it relates to the IEC standards used internationally, what tests manufacturers must pass to claim certification, and how to verify a supplier's certification before you award a contract.

VIKCHEM (Vikram Power Technologies Private Limited) has manufactured IS 13573 certified cable accessories since 1988. Every product in our heat shrink termination kit, cable jointing kit and power cable accessories ranges is independently tested and certified to IS 13573.

What Is IS 13573?

IS 13573 is the Bureau of Indian Standards (BIS) specification titled "Joints and Terminations for Polymeric Cables for Working Voltages from 1.1kV up to and including 33kV — Methods of Test and Requirements."

It is published by the Bureau of Indian Standards (BIS), Government of India, and is mandatory for cable accessories supplied to:

●Central and state electricity utilities (DISCOMs, TRANSCOs)
●Indian Railways and Metro Rail projects
●Government-funded infrastructure projects under MoP/MoHUA
●Public sector undertakings (NTPC, POWERGRID, NHPC, etc.)

The standard covers heat shrink, cold shrink, push-on and resin jointing and termination systems for polymeric-insulated cables (XLPE, PVC, EPR). It does not cover accessories for PILC (paper insulated lead covered) cables — those are covered by IS 5831 and related standards.

IS 13573 Voltage Classes

IS 13573 organises cable accessories into voltage classes that align with India's power distribution network:

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A manufacturer certified for 11kV is not automatically certified for 33kV — each voltage class requires separate testing and certification. Always confirm the voltage class on the manufacturer's BIS certificate.

What Tests Does IS 13573 Mandate?

IS 13573 prescribes a structured sequence of electrical, mechanical and environmental tests. These are divided into:

Type Tests (Qualification Tests)

Type tests are performed once to qualify a new product design. They are the most rigorous tests and include:

1. Partial Discharge Test The most sensitive electrical test for cable accessories. Partial discharges (PD) are tiny electrical discharges in voids or at interfaces within the accessory. High PD activity predicts premature insulation failure.

●Test voltage: 1.5 U₀ (U₀ = phase-to-earth voltage)

●Acceptance criterion: No detected discharge above the specified level (typically 10 pC for MV accessories)

2. Tan Delta (Dielectric Loss Factor) Test Measures the dielectric quality of the insulation system. A high tan delta indicates moisture contamination or poor material quality.

3. Lightning Impulse Withstand Test Simulates the voltage spike caused by a lightning strike reaching the cable system via overhead lines. The accessory must withstand the full impulse voltage (e.g., 95kV peak for 11kV class) without breakdown.

4. Power Frequency Withstand Voltage Test A continuous AC voltage applied for one minute to verify basic insulation integrity.

5. Long Duration Test (Long-Term Electrical Test) The most time-consuming and expensive type test. The accessory is subjected to continuous AC voltage at elevated temperature for a minimum of 1000 hours (IS 13573 specifies the duration by voltage class). This simulates years of in-service electrical stress.

6. Thermal Cycling Test The accessory-termination assembly is cycled between maximum conductor temperature (typically 90°C for XLPE) and ambient temperature repeatedly. This verifies that thermal expansion and contraction do not open up gaps or sealing interfaces that could admit moisture.

7. Bending Test For termination kits, the cable+termination assembly is bent at a specified radius to verify mechanical integrity.

8. Mechanical Pull-Out Test Tests the bond between the accessory and the cable at the critical interface zones.

9. Weather Resistance Test (Outdoor Terminations Only) UV and ozone exposure testing to verify material stability for outdoor applications.

Routine Tests (Production Tests)

Routine tests are performed on every production batch before dispatch. IS 13573 routine tests typically include:

●Visual inspection (no surface defects, correct dimensions)

●Partial discharge measurement on a sample from each batch

●Electrical resistance of semi-conducting components (where applicable)

●Dimensional verification

Sample Tests

Sample tests are performed periodically on production samples — less frequent than routine tests but more thorough. They bridge the gap between the one-time type test and the per-batch routine tests.

IS 13573 vs IEC 60502-4: Key Differences

International specifications use IEC 60502-4 (for polymeric cables up to 30kV) and related IEC standards. IS 13573 is substantially aligned with IEC but with important India-specific adaptations:

|--------|----------|-------------|

Voltage Class	System Voltage	Typical Applications
1.1kV	Up to 1.1kV (LV)	LV distribution, industrial wiring
3.3kV	3.3kV (3.6kV class)	Distribution feeders, industrial MV
6.6kV	6.6kV (7.2kV class)	Urban distribution networks
11kV	11kV (12kV class)	India's most common MV voltage
22kV	22kV (24kV class)	Sub-transmission
33kV	33kV (36kV class)	Primary transmission, large EPC
Aspect	IS 13573	IEC 60502-4
Voltage coverage	1.1kV to 33kV	1kV to 30kV
System voltage basis	Indian grid voltages (11kV, 33kV)	European voltages (10kV, 20kV, 30kV)
Long duration test	1000 hours minimum	1000 hours minimum
Impulse levels	As per IS 1885 system voltages	As per IEC 60071
Indian climate adaptation	Yes — tropical temperature, humidity	No — European baseline
Acceptance in tenders	Mandatory for Indian utilities	Acceptable for export/international projects

both

How to Verify IS 13573 Certification

The most common fraud in cable accessories procurement is the false claim of IS 13573 certification. A supplier may print "IS 13573" on packaging or quotes without holding a valid current certificate.

Step 1 — Request the BIS Licence Certificate

Every IS 13573 certified manufacturer holds a BIS licence number in the format CM/L-XXXXXXX. This is issued by the Bureau of Indian Standards. Request a copy of the current BIS licence certificate — it must show:

●The manufacturer's legal name and factory address
●The specific IS 13573 voltage classes covered
●The licence validity period (typically renewed annually)

Step 2 — Verify on the BIS Portal

Cross-check the licence number at the official BIS portal at bis.gov.in → Certification → ISI Mark → Licence Verification. Enter the CM/L number and confirm it matches the manufacturer, standard and products.

Step 3 — Check Voltage Class Coverage

A BIS licence may cover only some voltage classes. A manufacturer certified for 11kV accessories may NOT be certified for 33kV. Confirm that the certificate explicitly covers the voltage class of your project.

Step 4 — Check the ISI Mark on Packaging

IS 13573 certified accessories must carry the ISI Mark (the Bureau of Indian Standards certification mark) printed or embossed on the product packaging. If the ISI mark is absent from kit packaging, the product has not been through BIS certification — regardless of what any document says.

Step 5 — Request Type Test Certificates

For high-value tenders, request the type test certificates issued by a BIS-accredited test laboratory (such as CPRI Bangalore, ERDA Vadodara, or STQC). These documents prove the specific product design passed the full IS 13573 type test sequence.

IS 13573 and Project Specifications

For engineers writing tender specifications and approved vendor lists, the standard specification clause for IS 13573 compliance is:

> "Heat shrink cable jointing kits / termination kits shall comply with IS 13573. The manufacturer shall hold a valid BIS licence (ISI Mark Scheme) for the applicable voltage class. Type test certificates from a BIS-accredited test laboratory shall be submitted with the bid."

For contracts funded by agencies such as RDSS (Revamped Distribution Sector Scheme), DDUGJY, or Saubhagya, IS 13573 compliance is mandatory for all medium voltage cable accessories. The BIS licence number must appear in the submission.

VIKCHEM's IS 13573 Certification

VIKCHEM (Vikram Power Technologies Private Limited) holds BIS licences under IS 13573 for heat shrink cable termination kits and heat shrink cable jointing kits across all applicable voltage classes from 1.1kV to 36kV. Our certification has been continuously maintained since our original qualification.

What this means for your project:

●You can list VIKCHEM on approved vendor lists without additional qualification testing
●VIKCHEM's BIS licence number is available for inclusion in tender documentation
●Type test certificates from CPRI/ERDA are available on request
●All kit packaging carries the ISI Mark

VIKCHEM products certified under IS 13573:

●Heat Shrink Cable Termination Kits — 1.1kV to 36kV (XLPE, PILC)
●Heat Shrink Cable Jointing Kits — 1.1kV to 36kV (XLPE, PILC, transition)
●Power Cable Accessories — Heat shrink tubing, bus bar tubing, mastic tape, breakout kits

Summary: IS 13573 Checklist for Procurement

Before awarding any cable accessories contract, verify:

●[ ] Supplier holds a current BIS licence (CM/L-XXXXXXX) for IS 13573
●[ ] The licence covers the correct voltage class for your project
●[ ] Licence validity is current (not expired)
●[ ] BIS licence verified on bis.gov.in (not just on supplier documentation)
●[ ] ISI Mark is present on product packaging
●[ ] Type test certificates from CPRI, ERDA or other BIS-accredited lab are available
●[ ] Type test covers the specific cable type (XLPE, PILC) used on your project
●[ ] Test reports are less than 5 years old (most utilities require this)

Contact VIKCHEM to request our BIS licence certificate, type test reports and technical data for tender submissions.

IS 13573: India's Cable Accessory Quality Standard – What Engineers and Procurement Teams Must Know