— A Practical Guide for Engineers, EPCs, and Plant Operators
In industrial instrumentation, cable fire performance is not a single requirement—it is a hierarchy of different protection needs. Yet engineers and procurement professionals frequently confuse the two most important IEC cable fire standards: IEC 60331 and IEC 60332. They are often mentioned in the same sentence, but they address completely different questions:
IEC 60332: Will this cable stop burning when the flame is removed?
IEC 60331: Will this cable keep working while it is burning?
This guide explains what each standard actually requires, how they differ, and when each one applies in industrial instrumentation projects.
1. IEC 60332: Flame Retardance – "Stop the Spread"
IEC 60332 is the international standard for testing the flame retardant properties of cables. Its core objective is to prevent fire from spreading along cable runs--21.
1.1 What It Tests
A flame retardant cable must:
Limit flame propagation — fire should not travel far along the cable
Self-extinguish — when the flame source is removed, the cable stops burning-21
Reduce smoke and toxic gas — in the case of halogen-free variants, to protect people and equipment--17
Flame retardant cables do not guarantee that the cable will continue to function during a fire. They only ensure that the cable does not become a pathway for fire to spread.
1.2 Standard Structure
IEC 60332 is divided into several parts, each covering different test configurations:
| Part | Test Type | Application |
|---|---|---|
| IEC 60332-1-2 | Single cable, vertical flame propagation | Tests a single insulated conductor or cable using a 1 kW pre-mixed flame- |
| IEC 60332-3 (Series) | Bunched cables, vertical flame propagation | Tests vertically mounted bundles of cables to assess flame spread in cable-dense installations- |
1.3 Grading
IEC 60332-3 categorises cables based on the severity of the flame test:
| Category | Test Severity | Typical Application |
|---|---|---|
| Category A | Most stringent | Cable-dense areas, offshore platforms, critical infrastructure- |
| Category B | Intermediate | General industrial cable trays |
| Category C | Standard | General-purpose installations- |
1.4 When to Specify IEC 60332
General industrial instrumentation cables
Cables installed in cable trays with multiple cables
Any installation where fire spread along cable routes must be prevented
Control rooms and cable galleries
2. IEC 60331: Fire Resistance – "Keep Working in a Fire"
IEC 60331 is the international standard for testing the circuit integrity of cables under fire conditions. Its core objective is to ensure that the cable continues to transmit signals or power during a fire-21-.
2.1 What It Tests
A fire resistant cable must:
Maintain circuit integrity — the cable continues to carry signals or power while exposed to flame--6
Withstand specified temperature and duration — typically 830°C or higher--6
Survive mechanical shock — in many parts of the standard, the cable is also subjected to mechanical impact during the fire-
2.2 Standard Structure
IEC 60331 is a multi-part standard with different test methods for different cable types and sizes:
| Part | Test Method | Applicable Cables |
|---|---|---|
| IEC 60331-1 | Fire with shock at ≥830°C | Cables rated ≤0.6/1.0 kV, overall diameter >20 mm--6 |
| IEC 60331-2 | Fire with shock at ≥830°C | Cables rated ≤0.6/1.0 kV, overall diameter ≤20 mm-25 |
| IEC 60331-3 | Fire with shock at ≥830°C, tested in a metal enclosure | Cables tested in a metal enclosure--23 |
| IEC 60331-4 | Fire with shock at ≥830°C | Cables rated >1 kV up to 30 kV, conductor sizes ≤120 mm²- |
2.3 Temperature and Duration Requirements
IEC 60331-1 specifies at least 830°C flame temperature with mechanical shock-6. IEC 60331-11 (apparatus standard for fire alone without shock) specifies a flame temperature of at least 750°C-25.
Historically, IEC 60331 has been associated with 750°C for 30–90 minutes (30, 60, or 90 minute grades)--17. The modern parts of the standard have evolved to include higher temperatures (830°C) and mechanical shock testing-.
2.4 When to Specify IEC 60331
Emergency shutdown (ESD) circuits
Fire pump control and power circuits
Critical safety instrumented systems (SIS)
Emergency lighting and communications
Any circuit that must remain operational during a fire
3. Head-to-Head Comparison
| Comparison Aspect | IEC 60332 | IEC 60331 |
|---|---|---|
| Core Objective | Prevent fire spread- | Maintain circuit integrity during fire- |
| Standard Type | Flame retardance | Fire resistance (circuit integrity) |
| Key Question | Will it stop burning? | Will it keep working? |
| Test Focus | Flame propagation distance, self-extinguishing-21 | Electrical continuity under flame-21 |
| Test Temperature | Flame temperature (varies by part) | ≥830°C (with shock)--25 |
| Test Duration | Until flame propagation stops | 30–120 minutes (specified duration)--17 |
| Mechanical Shock | Not typically | Yes (in many parts)-6 |
| Applicable Cables | All cables (single and bunched)- | Power, control, data, and fibre optic cables- |
| Typical Application | General industrial cables | Emergency and safety circuits |
4. The Critical Distinction: Complementary, Not Alternative
IEC 60331 and IEC 60332 are complementary standards, not alternatives--17. A cable can—and often should—meet both requirements.
| Requirement | Standard | Purpose |
|---|---|---|
| Flame retardant | IEC 60332 | Fire does not spread along the cable route |
| Fire resistant | IEC 60331 | Cable continues to function during the fire |
In critical infrastructure, cables are often required to comply with both standards-17. A fire resistant cable that does not limit flame spread could still allow fire to travel along its length. A flame retardant cable that fails under fire cannot perform its safety function.
5. Practical Applications in Instrumentation
5.1 When to Specify IEC 60332 Only
Standard instrumentation cables for non-critical loops
General control cables
Cables in well-protected, low-risk areas
5.2 When to Specify IEC 60331 Only
Fire resistant cables for emergency circuits
Cables that must maintain signal integrity during fire
ESD and fire pump circuits
5.3 When to Specify Both
Critical safety loops in high-risk areas
Offshore platforms (where both flame spread and circuit integrity are critical)
Cables in control rooms and cable galleries
6. Common Mistakes to Avoid
| Mistake | Consequence | Prevention |
|---|---|---|
| Assuming flame retardant = fire resistant | Safety circuits fail during fire | Understand the difference; specify both where required |
| Specifying IEC 60332 when IEC 60331 is required | Critical circuits lose function in fire | Identify safety-critical circuits early |
| Using IEC 60331 cables unnecessarily | Higher cost, over-specification | Apply fire resistance only where circuit integrity is required |
| Ignoring mechanical shock testing | Cable fails under real fire conditions | Specify the correct part of IEC 60331 (with shock) for demanding applications |
| Not verifying both standards in one cable | Missing complementary protection | Check whether the cable meets both flame retardance and fire resistance |
7. Why Choose Anhui Tiankang for Fire Performance Cables?
Anhui Tiankang (Group) Co., Ltd. has been manufacturing industrial cables for nearly five decades. Our fire performance instrumentation cables are designed to meet the most demanding international standards.
Fire Performance Cable Portfolio:
| Cable Type | Standards Met | Typical Application |
|---|---|---|
| Flame retardant instrumentation cables | IEC 60332-1, IEC 60332-3 (Cat A/B/C) | General industrial installations |
| Fire resistant instrumentation cables | IEC 60331-1, IEC 60331-2 | ESD, fire pumps, critical safety circuits |
| Fire resistant + LSZH cables | IEC 60331 + IEC 60754 + IEC 61034 | Offshore platforms, control rooms, confined spaces |
| Armoured fire resistant cables | IEC 60331 + mechanical protection | Direct burial, high-risk areas |
Core Advantages:
Full certification – CCC, ATEX, IECEx, CCS marine
CNAS-accredited laboratory – Complete fire performance testing
Proven track record – Long-term supplier to CNPC, Sinopec, CNOOC, and international EPC projects
Complete package – From instrumentation to cables to Ex cable glands
8. Conclusion
IEC 60331 and IEC 60332 serve fundamentally different purposes:
| Standard | Purpose | Best Described As |
|---|---|---|
| IEC 60332 | Stop fire from spreading along the cable | Flame retardance |
| IEC 60331 | Keep the cable working during a fire | Fire resistance (circuit integrity) |
One is about containment — preventing fire from travelling. The other is about survival — ensuring critical circuits keep functioning.
The key takeaway: These are not alternatives. They are complementary requirements. For critical safety circuits, you need both: a cable that will not spread fire (IEC 60332) and will continue to function during the fire (IEC 60331).
Contact Us
For fire performance cable selection advice, technical documentation, or project quotations, please contact:
Yin Shuangjie
International Sales Manager
📧 Email: [email protected]
📱 WhatsApp / Zalo: +86 17856068126
🌐 Website: http://www.tiankang-global.com/
Anhui Tiankang – Your partner for reliable fire performance cable solutions.
