— Selection Guide for Fire Resistant Instrumentation Cables

In high‑risk industrial facilities such as petrochemical plants, offshore platforms and LNG terminals, fire not only destroys equipment and structures but can also lead to fatal production accidents and environmental pollution. Once a fire breaks out, conventional signal circuits will short‑circuit or open due to insulation melting, causing operators to lose monitoring and control over actuators, emergency shutdown valves and fire pumps. Whether fire‑fighting, emergency shutdown and critical safety interlock circuits can continue to operate during a fire directly determines whether an incident can be contained in time.

With nearly five decades of experience in wire and cable manufacturing, Anhui Tiankang (Group) Co., Ltd. possesses domestic advanced IE‑class K3 nuclear cable technology, applying its high‑reliability nuclear‑grade standards to the fire‑resistant instrumentation cable quality system. Based on this background, this article systematically presents the key points of fire‑resistant instrumentation cable selection, covering the core definition, standard systems, selection steps and Tiankang product advantages.

1. Core Definition of Fire Resistant Cable

A fire resistant cable is defined as a cable that can maintain circuit integrity and continue to transmit signals for a specified period while directly exposed to flame. This is fundamentally different from a flame retardant cable: flame retardance concerns “no flame propagation after the fire source is removed”, while fire resistance concerns “the cable continues to function during the fire”.

According to GB/T 19666‑2019 General rules for flame retardant and fire resistant electric wires and cables or optical fibre cables, fire resistant cables must use copper conductors with rated voltage ≤0.6/1kV, and the insulation shall have fire resistant characteristics; otherwise a fire resistant layer shall be applied over the conductor and/or cable core. The fire resistant layer is typically made by wrapping fire resistant mica tape, and the thickness, number of layers and lapping ratio are determined by the manufacturer. Fire resistant cables must also meet flame retardant requirements, and low smoke zero halogen products must pass smoke density and halogen gas tests.

In the field of instrumentation cables, fire resistant cables usually adopt a composite insulation structure of “mica tape + XLPE/EPR/silicone rubber”. When exposed to flame, the mica tape forms a hard insulating layer that prevents short circuits between conductors, allowing the loop to continue powering or transmitting signals.

2. Step 1 – Identify the Need for Fire Resistant Cables in Your Project

Not every instrumentation loop needs fire resistant cable. Over‑specifying adds unnecessary cost, while under‑specifying creates safety risks. The following loops are strongly recommended or mandatory for fire resistant cables:

Tiankang recommendation: During the design phase, process safety engineers should define a “critical loop list” to determine which instrumentation cables require fire resistant construction. For non‑critical loops, flame retardant cables are sufficient and should not be unnecessarily upgraded.

3. Step 2 – Understand the International Fire Resistant Cable Standard System

The performance of fire resistant cables is defined and classified by a series of international and national standards. The following key standards must be understood by engineers:

3.1 Chinese Standard: GB/T 19666‑2019

The current effective Chinese general standard for fire resistant cables. GB/T 19666‑2019 General rules for flame retardant and fire resistant electric wires and cables or optical fibre cables was issued by the Standardization Administration of China and became effective on 1 July 2020, replacing the 2005 version. It mainly specifies:

• Circuit integrity requirements for fire resistant cables

• Fire resistant cables must also meet flame retardant performance (single or bunched)

• Low smoke zero halogen fire resistant cables must additionally meet smoke density (light transmittance ≥60%) and halogen gas release (pH ≥4.3) requirements

• The fire resistant layer is typically made by wrapping fire resistant mica tape; thickness, number of layers and lapping ratio are determined by the manufacturer

Type designation: NH denotes fire resistance; e.g. NH‑VV, NH‑VV22, etc.

3.2 International Standard: IEC 60331 Series

IEC 60331 is the most widely used international standard for cable fire resistance testing, titled Tests for electric cables under fire conditions – Circuit integrity. IEC 60331‑1:2018 specifies the test method for maintaining circuit integrity under flame at least 830°C and mechanical shock, applicable to cables with rated voltage ≤600/1000V. IEC 60331‑21 covers circuit integrity under vertical flame exposure.

Tiankang products: Tiankang fire resistant instrumentation cables have passed IEC 60331‑21 testing, meeting entry requirements for international engineering projects.

3.3 British Standards: BS 6387 and BS EN 50200

BS 6387 was once a globally recognised high‑level fire resistant cable standard, containing three independent tests: C (fire resistance), W (fire + water spray) and Z (fire + mechanical shock). The highest level is CWZ, which requires: 950°C flame for 180 minutes (C); 650°C flame + water spray for 45 minutes (W); and 950°C flame + mechanical shock for 15 minutes (Z).

Current British standards have migrated to BS EN 50200, which tests cables up to 20 mm diameter under 830°C flame and mechanical shock, classifying into PH15, PH30, PH60, PH90 and PH120 based on duration.

Tiankang products: Tiankang fire resistant instrumentation cables meet IEC 60331 series requirements and comply with both domestic and mainstream international engineering acceptance criteria.

3.4 Marine & Offshore Standards: IEC 60092 Series, IEEE 1810

For instrumentation cables on ships and offshore oil platforms, IEEE 1810‑2025 Guide for Installation of Circuit‑Integrity Cables Evaluated for Hydrocarbon Pool Fires in Petroleum and Chemical Facilities applies to emergency and safety shutdown systems in petroleum, chemical and offshore platforms. Marine fire resistant cables must also meet the low smoke zero halogen and fire resistance requirements of the IEC 60092 series (Electrical installations in ships).

Tiankang certification: Tiankang products hold China Classification Society (CCS) certification and are suitable for marine and offshore platform projects.

4. Step 3 – Determine the Required Fire Resistance Rating

Select the appropriate fire resistance rating based on project specifications and safety requirements:

Selection reference: General petrochemical critical instrument loops require fire resistance ≥90 minutes. Offshore platforms shall follow IEEE 1810 with hydrocarbon pool fire assessment. Domestic projects follow GB/T 19666 and project technical specifications.

5. Step 4 – Confirm Comprehensive Performance of Instrumentation Cables

In addition to fire resistance, fire resistant instrumentation cables must possess other core instrumentation cable properties:

5.1 Shielding Performance

Instrumentation cables carry milliampere‑level or millivolt‑level weak signals and are highly sensitive to electromagnetic interference. Fire resistant instrumentation cables typically adopt copper wire braid shielding or composite foil + braid shielding with shielding coverage ≥80%. For multi‑pair cables, individual pair shields plus an overall shield can be used to prevent crosstalk.

5.2 Intrinsic Safety Performance

If the fire resistant cable is used in an intrinsically safe circuit, it must also meet distributed capacitance and inductance parameter matching, the outer sheath is typically blue, and the cable must carry intrinsic safety certification.

5.3 Low Smoke Zero Halogen (LSZH) Performance

In confined spaces such as control rooms, offshore platforms and underground cable galleries, smoke and acid gases generated during fire seriously endanger personnel and equipment. Fire resistant instrumentation cables should simultaneously meet:

• Low smoke (IEC 61034) : Light transmittance ≥60% during combustion

• Halogen free (IEC 60754‑2) : Combustion gas pH ≥4.3, conductivity ≤10 μS/cm

5.4 Oil & Chemical Resistance

For oily environments such as refineries and chemical plants, the cable sheath must be oil and chemical resistant. Oil‑resistant LSZH or oil‑resistant PVC sheaths are typically used; in high‑temperature areas, fluoroplastic (FEP/PFA) sheaths are used.

Tiankang products: Tiankang fire resistant instrumentation cable series cover all the above performance requirements, with customisable shielding structures, sheath materials and fire resistance ratings based on project needs.

6. Installation Considerations

Proper installation is essential for fire resistant cable performance:

• Bending radius – Due to the mica tape fire resistant layer, fire resistant instrumentation cables are less flexible than ordinary cables. The bending radius during installation should not be less than 8–12 times the cable outer diameter.

• Cable glands – Glands are often the weakest point during fire. Use explosion‑proof or fire resistant cable glands and seal them strictly according to the product manual.

• Separation from other cables – Fire resistant cables should not be mixed with ordinary cables in the same tray, otherwise heat from burning ordinary cables may prematurely damage the fire resistant cables.

• Armour grounding – For armoured fire resistant instrumentation cables, the armour must be reliably grounded at one end as per code.

7. Advantages of Anhui Tiankang Fire Resistant Instrumentation Cables

Founded in 1974, Anhui Tiankang (Group) Co., Ltd. is a leading integrated manufacturer of instruments and wires/cables in China. In the field of fire resistant instrumentation cables, we offer the following core advantages:

7.1 Complete Product Range

Tiankang‘s cable portfolio includes: computer (shielded) cables, instrumentation signal cables, flame retardant and fire resistant cables, intrinsically safe (DCS system) cables, low smoke low halogen / zero halogen cables, and more. Fire resistant cable types include NH‑VV, NH‑VV22 and fire resistant computer cable DJYPV‑NH.

7.2 Nuclear‑Grade Technology

Tiankang’s independently developed IE‑class K3 nuclear cables are at the domestic advanced level and are widely used in the nuclear power industry. The technical requirements for nuclear cables are far more stringent than for ordinary fire resistant cables, and this technological depth gives Tiankang fire resistant instrumentation cables extra reliability.

7.3 Full Performance Testing Capability

Tiankang possesses a CNAS‑accredited laboratory capable of performing flame combustion tests, circuit integrity tests, smoke density tests, halogen gas content analysis, as well as full electrical performance tests such as shielding effectiveness, capacitance and insulation resistance – ensuring factory data is authentic and reliable.

7.4 Comprehensive Certifications

• Quality management – ISO 9001, ISO 14001, ISO 45001

• Explosion protection – National Ex certification (CCC); intrinsically safe cables comply with GB 3836.4

• Classification society – China Classification Society (CCS) certification, suitable for offshore platform and marine projects

• Flame retardance / fire resistance – Comply with GB/T 19666, IEC 60331, IEC 60332 series

7.5 Industry Track Record

Tiankang products are widely used in petroleum, chemical, power, metallurgy and other industries, serving major projects including Yangzi Petrochemical, Yanshan Petrochemical, Daqing Oilfield, Daya Bay Nuclear Power, as well as export projects to Sudan, Pakistan, Guinea and many others.

8. Selection Reference Table

9. Conclusion

Fire resistant instrumentation cables are the “last line of defence” in safety design for high‑risk industries such as petrochemical and offshore. Correct selection requires identifying critical loops, understanding the international standard system (GB/T 19666, IEC 60331, BS EN 50200 and marine standards), determining the appropriate fire resistance rating, and addressing core instrumentation properties such as shielding, intrinsic safety and low smoke zero halogen characteristics.

With nearly five decades of instrumentation cable manufacturing experience, nuclear‑grade technology and CNAS‑accredited testing capability, Anhui Tiankang (Group) Co., Ltd. provides highly reliable fire resistant cable products and full technical support for your critical instrument loops.

Contact Us

For fire resistant instrumentation cable selection advice, technical documentation or project quotations, please contact:

Yin Shuangjie
📧 Email: [email protected]
📱 WhatsApp / Zalo: +86 17856068126
🌐 Website: http://www.tiankang-global.com/

Anhui Tiankang – providing safe, reliable fire resistant protection for your critical control loops.