— How to Prepare Instrumentation Cable Technical Specifications in EPC Tender Documents

In EPC (Engineering, Procurement, Construction) projects, the instrumentation cable technical specification is a critical document linking design and procurement. A clear, complete, and unambiguous specification enables contractors to quote accurately, reduces technical clarifications and variations, and ensures that the delivered products meet project requirements. Conversely, a vague specification can lead to off‑target quotations, supply deviations, field installation difficulties, and even safety and quality incidents.

Based on nearly five decades of experience in instrumentation cable manufacturing and EPC project supply, Anhui Tiankang (Group) Co., Ltd. presents a systematic guide to preparing instrumentation cable technical specifications – covering the structure, core content, and key considerations – to help EPC project engineers develop professional, rigorous, and executable specifications.

1. Core Role and Positioning of the Instrumentation Cable Specification

In an EPC tender document package, the instrumentation cable technical specification is typically part of the technical volume, together with commercial terms, drawing lists, scope of supply, etc. Its core functions include:

• Define technical requirements – Specify design, materials, manufacturing, testing, packing, marking, and all technical standards throughout the cable life cycle.

• Provide a uniform basis for quotation – Enable all bidders to quote on the same technical platform, facilitating comparison.

• Define responsibility boundaries – Clarify the scope of responsibility between buyer and seller to avoid disputes during contract execution.

• Serve as the basis for acceptance – The specification is a key reference document for Factory Acceptance Testing (FAT) and site acceptance.

Tiankang note: The specification should be prepared following the principles of “clear, complete, verifiable”. Any ambiguous or omitted technical requirement may cause disputes later. If any omission in this specification may affect cable performance requirements, the Seller shall draw the Buyer‘s attention in writing and shall supply products of acceptable quality. If the Seller’s products deviate from the requirements of this specification, they shall be stated in the bid; otherwise it shall be understood that all requirements of this specification are fully satisfied.

2. Standard Format of the Instrumentation Cable Specification

A complete instrumentation cable technical specification is typically organised in the following chapter structure:

The following sections explain the essential elements of each chapter in detail.

3. Detailed Guidance for Each Chapter

3.1 Scope

The scope section should briefly state the applicability of the specification and the project background, including:

• Types of cables covered (instrumentation cable, computer cable, intrinsically safe cable, compensating cable, etc.)

• Project name and location

• Systems and areas where cables will be used (DCS, ESD, field instrument loops, etc.)

• Boundaries of the supply scope (e.g., whether cable glands, terminations, markers, etc. are included)

Example wording:

“This specification covers the minimum requirements for the design, manufacture and testing of instrumentation cables. It applies to all instrumentation signal cables from field instruments/junction boxes to control room/equipment rooms for this project.”

In addition, the handling of deviations should be clearly stated: if the Seller‘s products deviate from the requirements of this specification, they shall be stated in the bid; otherwise it shall be understood that all requirements of this specification are fully satisfied.

3.2 Codes & Standards

This is one of the most technically intensive parts of the specification, directly determining cable quality and compliance. List all applicable domestic and international standards with edition numbers (or “latest edition” if appropriate).

3.2.1 Common Chinese Standards

3.2.2 Common International Standards

3.2.3 Standard Priority Order

Clearly state the priority rule when conflicts arise between the specification and referenced standards. A typical priority order is:

1. Project technical specification (this document)

2. Project‑specific codes

3. International standards (IEC)

4. National standards (GB/EN/ANSI, etc.)

Example wording:

“In case of conflict between this specification and the above standards, this specification shall prevail. If the manufacturer cannot comply with the standards listed in this specification, they shall state this in their bid.”

Some international projects also require strict declaration of any deviation: any cable component not explicitly mentioned in the specification (e.g., inner plastic tape, barrier tape, water‑blocking yarn) even if considered part of standard production, must be fully described by the manufacturer, including type, composition, dimensions, tolerances, minimum thickness and colour. An A4‑size cross‑section drawing of the cable should be provided, showing the arrangement of all cores and layers, lapping lengths, positions of all materials, and dimensional tolerances.

3.3 Service Conditions

The service conditions section should list the environmental parameters for cable installation and operation, enabling suppliers to select appropriate materials and construction:

For marine or offshore platform projects, additionally state: cables shall be suitable for salt spray corrosion and shall hold relevant classification society certification. Also specify that the operating temperature of the cable shall not exceed the design limits. Typically, continuous maximum conductor operating temperatures are: 70°C for PE insulation, 90°C for XLPE, and 200°C for fluoroplastic.

Tiankang tip: The more detailed the service conditions, the more accurate the supplier‘s selection. Common omissions include: “minimum installation temperature” (affects winter installation), “continuous maximum operating temperature” (affects insulation material choice), and “type of corrosive media” (affects sheath material).

3.4 Design Requirements

This is the core technical chapter. Present requirements in a table format for clarity.

3.4.1 General Requirements

For high‑temperature environment projects, such as around cracking furnaces or reactors, specify: for heat‑resistant instrumentation cables, in addition to standard requirements, the insulation and outer sheath material shall be polytetrafluoroethylene (PTFE/Teflon), and the cable shall be capable of continuous operation at 205°C.

3.4.2 Conductor Requirements

The conductor is the core of signal transmission. Specify:

• Conductor material: annealed oxygen‑free copper or tinned copper (for corrosion resistance)

• Conductor stranding: number of strands and individual wire diameter (e.g., 7×0.2mm)

• Conductor size: determined by signal type and transmission distance

• Conductor resistance: shall comply with IEC 60228; provide maximum allowable values

For thermocouple compensating cables, also specify the conductor material matched to the thermocouple type (e.g., Ni‑Cr / Ni‑Al for Type K), in accordance with ANSI MC 96.1.

3.4.3 Shielding and Twisting Requirements

Shielding construction directly affects instrumentation cable noise immunity. Specify:

• Analog signal cables (4‑20mA, thermocouple): twisted pair + individual shield + overall shield

• Digital communication cables (RS‑485): twisted pair + overall shield, characteristic impedance 120Ω ±10%

• Discrete signals: overall shield only (or as per design)

For individual shielding, may specify aluminum/polyester tape wrapping, minimum thickness 28µm, coverage 100%, overlap ≥25%, with the metallic side in reliable contact with the drain wire. For overall shielding, similar material with thickness at least 60µm. The drain wire shall be stranded tinned annealed copper.

3.4.4 Sheath and Armour Requirements

• Outer diameter tolerance – Finished cable OD tolerance typically ±2mm relative to the manufacturer’s declared value; variation along the cable shall not exceed 1.0mm.

• Ovality – Ovality at any cross‑section shall not exceed 1.0mm.

• Armour material – Galvanized steel wire or steel tape; material certificate required.

• Armour grounding – The armour shall be capable of being reliably grounded via cable glands.

3.4.5 Marking Requirements

Specify the marking on the cable outer sheath to aid field identification and traceability:

• Manufacturer‘s name or trademark

• Cable type and size (number of cores × cross‑section)

• Voltage rating

• Year of manufacture

• Length marking (continuous per metre or every 5 metres)

• Flame retardant/fire resistant/IS identification (e.g., FRLS, NH, ia)

• IS cables: blue outer sheath; other cables as per project colour code

Marking methods include indented, ink‑jet, and raised. Specify clearly: IS cables shall have a blue outer sheath; non‑IS cables may be black or grey.

3.5 Testing & Inspection

The testing and inspection section defines the mandatory tests and acceptance criteria. It is the rigid quality control boundary. Tests shall include at least the following categories:

3.5.1 Type Tests

Type tests shall be performed on a representative cable sample to verify design compliance. Typical tests include:

• Electrical: conductor resistance, insulation resistance, dielectric strength

• Mechanical: tensile strength, elongation at break, cold bend

• Environmental: low temperature bending, heat ageing, ozone resistance

• Flame retardance / fire resistance: IEC 60332‑1 / ‑3, IEC 60331

• LSZH: pH, conductivity, light transmittance (if applicable)

Reference standards: Detailed type test requirements may refer to IEC 60331‑21 and BS EN 50200 (with additional mechanical shock). If the higher BS 6387 CWZ level (C:950°C/180min, W:650°C+water spray, Z:950°C+shock) is required, state it explicitly.

3.5.2 Routine Tests

100% tests performed on each drum of cable before dispatch:

• Conductor continuity

• Insulation resistance (500V DC, core‑core, core‑earth)

• Dielectric strength (power frequency withstand)

Some specifications require routine tests to be witnessed by an independent third‑party laboratory (e.g., NABL or CNAS accredited) and to provide traceable test certificates.

3.5.3 Sample Tests

Perform more comprehensive tests on samples taken from each batch:

• Dimensional inspection (conductor diameter, insulation thickness, sheath thickness, armour gauge)

• Mechanical properties before and after heat ageing

• Shielding coverage check

• Flame retardance / fire resistance (at frequency specified by project)

3.6 Marking & Packing

3.6.1 Marking Requirements

Outer sheath marking shall include:

• Manufacturer‘s name or trademark

• Cable type and size (cores × cross‑section)

• Voltage rating

• Year of manufacture

• Length marking

• Flame retardant / fire resistant / IS identification (e.g., FRLS, NH, ia)

For international procurement, the manufacturer shall apply durable markings on the cable outer sheath at intervals not exceeding 625mm, including manufacturer’s name, insulation material, conductor size, number of pairs, voltage rating, cable type and year of manufacture. Sequential automatic length marking (meter marks) at intervals of 1 metre is required. Also specify the accuracy of the length marking (typically ±0.5%).

3.6.2 Cable Drum Requirements

• Drums shall be robust, free from deformation, suitable for long‑distance transport and multiple handling

• For export projects, use ISPM 15 certified fumigated wooden drums

• Labels firmly affixed to each drum, showing: project name/number, contract number, cable type, size, length, gross weight, net weight, drum number

• The outer end of each cable drum shall be sealed to prevent moisture ingress

3.6.3 Packing and Transport

Cables shall be properly packed to prevent moisture and mechanical damage during transport and storage. For sea freight, packing shall be resistant to seawater corrosion; all metal parts shall be coated with anti‑rust oil.

3.7 Documentation

Clearly list the required documents for the bid stage and contract execution stage.

Bid stage:

• Product samples and selection guide

• Typical technical datasheet

• Outline dimension drawing (including minimum bending radius)

• Sample material certificate

• Scanned copy of Ex certificate (if applicable)

• Calibration report template

• Quality plan

Contract execution stage:

• Final technical datasheet

• Detailed outline drawing, installation drawing (including cable cross‑section)

• Material certificate (EN 10204 Type 3.1)

• Routine test report

• Type test report

• Original or certified copy of Ex certificate

• Operation and maintenance manual

• “As‑built” drawings

• Cable schedule in Excel format by tag

Some high‑standard EPC projects also require the bidder to submit a self‑check checklist together with the technical bid, covering all categories (power, control, instrumentation, fire & gas, telecom, fibre optic), verified by internal/external review before formal issuance.

3.8 Cable Schedule

The cable schedule is one of the most important attachments to the specification. Provide it in Excel format with at least the following fields:

For overseas EPC projects, it is advisable to include a “Guaranteed Technical Particulars” form that the bidder must fill out, covering manufacturer name, cable type, conductor construction, DC resistance, insulation resistance, capacitance, and other electrical parameters with guaranteed values and test standards. Some international projects require detailed electrical design calculations for the cables.

4. Common Specification Errors and How to Avoid Them

5. Tiankang‘s Specification Preparation Support Services

With nearly five decades of experience in wire and cable manufacturing and EPC project supply, Anhui Tiankang (Group) Co., Ltd. offers the following specification preparation support:

• Provide standard technical datasheet templates for instrumentation cables

• Assist in preparing cable schedules and guaranteed technical particulars

• Provide electrical parameter calculation support for IS cables (capacitance, inductance, etc.)

• Provide technical parameters and test report templates for flame retardance, fire resistance, LSZH, etc.

• Customise special cable constructions (non‑standard pair counts, special sheaths, special armour) to project requirements

• Provide bilingual (English/Chinese) technical documentation to meet international EPC document management requirements

• Support FAT witness testing and provide complete factory quality documentation packages

• Assist EPC contractors with cable selection optimisation and technical clarifications

Tiankang products hold ISO 9001, ISO 14001, ISO 45001 certifications, national Ex certification (CCC), ATEX, IECEx, SIL, and China Classification Society (CCS) certification, suitable for both domestic and international EPC projects.

6. Conclusion

Preparing a high‑quality instrumentation cable technical specification requires engineers to have a deep understanding of cable products, a thorough grasp of project service conditions, and accurate knowledge of the standards system. By clearly defining the scope, referencing appropriate standards, specifying detailed technical requirements, defining testing and inspection, and standardising marking, packing and documentation, procurement risk can be significantly reduced, ensuring that the supplied cables meet project needs.

With nearly five decades of professional experience, Anhui Tiankang (Group) Co., Ltd. is ready to provide full support for EPC projects – from specification preparation consulting, cable selection optimisation, to product supply and quality assurance.

Contact Us

For instrumentation cable specification templates, technical data, or selection support, please contact:

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

Anhui Tiankang – providing professional, reliable instrumentation cable technical specification support for your EPC projects.