Instrumentation Cable and Wiring Inspection Procedure: Essential  checklist for Project Engineers

This procedure ensures the reliability and accuracy of the instrumentation system by following standard guidelines to prevent equipment failures and hazards. The outlined approach emphasizes documentation, planning, collaboration, and adherence to safety protocols to conduct comprehensive cable and wiring inspections.

Planning Phase Documentation Review

Before the physical inspection begins, the initial phase of document analysis helps highlight areas that require correction, laying the foundations for a successful and compliant assessment.

Review the following documents carefully prior to the inspection to ensure that all project requirements and specifications are fulfilled:

• Cable Schedule: Verify the list of cable types, lengths, and termination details against project requirements.
• Cable Layout Drawings: Examine the routing paths, cable entry points, and overall layout to ensure correct installation and compliance.
• Single-Line Diagrams (SLDs): Confirm connections, voltage levels, and grounding requirements.
• Cable Tray layout Plans: Check tray placement, spacing, and load capacity, ensuring they meet project specifications.
• Hazardous Area Classification Drawings: Verify that cables meet the specifications for their designated hazardous areas (e.g., ATEX, IECEx).
• Loop Diagrams: Understand the signal flow from field devices to the control system for accurate testing and verification.
• Review all manufacturer installation and testing standards to ensure that the cables are installed and tested correctly, according to best practices.

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Refer the below link for the Types of Engineering Drawings and Documents used in Instrumentation

Tools and Team Coordination

Efficient organization of inspection tools and coordination with relevant teams are essential for smooth inspection operations.

Tools Preparation

Prepare the necessary inspection tools to cover all testing and verification needs:

• Multimeters – For checking continuity and voltage levels.
• Insulation Testers – To test insulation resistance and identify any potential leakage.
• Crimping Tools – For securing terminations with proper compression and reliability.
• Megger Testers – To measure insulation resistance in higher voltage applications.
• Labels – For marking cables, indicating test results, or tagging areas needing rework.

Coordination with Teams:

• Cable Laying Team: Confirm that cable laying activities are complete and that cables are ready for inspection, minimizing rework or delays.
• Erection Team: Verify that equipment is placed and does not obstruct cable access or inspection activities. This ensures clear inspection paths and minimizes interference.

Safety Measures

Before beginning the inspection, implement the following safety measures to protect personnel and ensure compliance with safety standards:

• Conduct a Job Safety Analysis (JSA): Identify potential hazards associated with the inspection activities, evaluate risks, and establish mitigation strategies. Share findings with the team in a pre-task safety briefing.
• Equip all personnel with the necessary PPE, such as: Insulated Gloves, Safety Boots,Helmets, Safety Goggles.
• Lockout/Tagout (LOTO): Ensure that all electrical circuits are de-energized and properly tagged and locked out to prevent accidental energizing during inspection.
• Place fire extinguishers and first aid kits at accessible locations near the inspection site in case of emergencies.
• Conduct toolbox talks before each inspection session to highlight specific risks associated with the day’s tasks and review safety precautions. This step ensures all team members are aware of potential hazards and are prepared to mitigate them.
• Ensure inspection areas are well-lit to enhance visibility and prevent accidents. Proper ventilation is also essential, especially in confined spaces or areas where fumes or dust could accumulate.
• Limit inspection zones to authorized team members only. This measure reduces the risk of interference, improves safety, and helps maintain control over the inspection environment.
• Develop clear communication protocols, especially in hazardous or confined spaces, to enable prompt coordination and ensure personnel safety

The inspection procedures include pre-installation, installation, and post-installation checks to ensure that all instrumentation cables are installed correctly, securely, and safely.

Pre-Installation Inspection

 Before laying cables, inspect the following:

Cable Quality

• Inspect cable drums for any physical damage from transportation or storage.
• Verify and confirm that the cable type, size, insulation material, and markings match project specifications.
• Ensure cables are stored in a dry, ventilated area, protected from environmental factors that could degrade the insulation.
• Confirm that electrical cables are appropriately sized and selected to support both current and future equipment requirements.

Click here for Common materials used in Instrumentation Cable

Conduits and Cable Trays

• Verify that cable trays are installed as per layout drawings and are adequately supported for the weight of the cables.
• Check that conduit runs are smooth, with proper bends, joints, and cleanliness to facilitate cable pulling without causing damage.
• Confirm that all conduits and trays are properly grounded per design requirements.

Grounding and Shielding

• Ensure that grounding connections are secure and follow the design specifications.
• Check that cable shields are grounded at only one end to prevent ground loops and minimize electromagnetic interference (EMI).

Click here for Different Types of Cables in Instrumentation and its Applications

Installation Inspection

During the cable laying and termination process, conduct the following inspections:

Cable Routing

• Confirm that cables are routed along designated paths as per the layout drawings, avoiding unnecessary deviations.
• Ensure cables are properly clamped and not over-tensioned or kinked during installation.
• Maintain adequate spacing between power and instrumentation cables to reduce EMI.
• In classified areas, ensure separation between intrinsically safe (IS) and non-intrinsically safe wiring to avoid potential hazards.
• Ensure mechanical protection is provided to minimize the risk of physical damage to cabling.
• Verify that cables are concealed, where possible, in ceiling spaces, wall cavities, or risers.

Termination:

• Check that cable insulation is stripped carefully without damaging the conductor.
• Verify the quality of crimping for lugs and ferrules, and ensure terminal screws are securely tightened without over-tightening.
• Confirm that all connections follow the correct polarity and test for continuity to ensure proper connections.
• Check that all connections are correctly terminated and insulated to ensure reliable connectivity and prevent faults or interference.

Segregation:

• Ensure segregation of signal cables based on their voltage levels and types (analog, digital, or communication).
• Follow project-specific standards, such as IEC 60079, for cable segregation in hazardous areas.

Environmental and Temperature Checks:

• Verify that cable insulation materials are suitable for ambient and operational temperatures to avoid deterioration over time.
• For outdoor or chemically-exposed areas, ensure cables are rated for UV and chemical resistance to maintain integrity in harsh environments.

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Cable Entry Points:

• Verify that cable entries are securely sealed with appropriate cable glands, especially in areas exposed to hazardous conditions.
• Confirm that the gland type and size match the cable diameter to ensure a secure fit and effective environmental protection.

Cable Pulling Tension and Bend Radius:

• Use tension meters to monitor cable pulling forces and ensure they remain within the manufacturer’s recommended limits.
• Check that all cables are installed with bends at or above the minimum recommended radius, particularly at sharp turns, to prevent conductor damage.

Cable Gland Torque Settings:

• Measure and confirm proper torque levels for all cable glands to prevent loosening over time, which could compromise environmental seals and protection.

Post-Installation Inspection

After the installation of instrumentation cables, conduct the following quality and functionality checks to ensure everything is correctly set up and operating safely.

Visual Inspection

• Inspect cables for any physical damage, ensuring they are routed correctly without strain, bends, or abrasions.
• Confirm that all cables are following designated routing paths, with no deviations from layout plans.
• Ensure that cables are clearly labeled at both ends to aid in easy identification during maintenance.
• Check that all clamps, ties, and fasteners are intact, securely holding cables in place to prevent movement or wear over time.

Testing

• Use a multimeter to verify that there are no open or short circuits in the wiring.
• Before handling any cables or equipment, ensure all circuits are completely de-energized. Follow Lockout/Tagout (LOTO) procedures to prevent accidental re-energizing during inspections.
• In cases where live testing is required, use only insulated tools designed for electrical work. This precaution protects against accidental contact with live components, reducing the risk of electrical shock.
• Perform insulation resistance testing with a megger tester, confirming that insulation values meet project or manufacturer standards to ensure safe operation.
• For Low-voltage Instrumentation Cables (below 1 kV): Minimum insulation resistance should be 1 MΩ per kilometer at 500V DC.
• For High-voltage Instrumentation Cables (above 1 kV): Minimum insulation resistance should be 5 MΩ per kilometer at 1000V DC.
• Conduct loop testing to check the entire signal loop’s end-to-end continuity and functionality.
• Verify that all connections are at the correct voltage levels and that polarity is accurate, preventing operational issues or equipment damage.
• Use a multimeter to check all field instrument cables for end-to-end continuity, identifying any breaks or shorts before termination at field instruments.
• A reading of 0 ohms (or very close to 0) indicates a continuous path, while a higher resistance may indicate a break or connection issue.
• Confirm that each field instrument has the correct number and type of cables as listed in the Cable Schedule provided by the specialist.
• Ensure all field instrument wiring terminations follow the specific installation instructions.
• Check that all field instrument wiring is properly dressed, furled, and crimped according to the specialist’s instructions.
• Verify internal wiring within panels is done according to the panel wiring diagram.
• Confirm that all field instrument cables, including those between the controller and MCC, are present in the controller cabinet, properly furled, dressed, and crimped.

Refer the below for voltage drop calculation of instrument cable

Thermal Scanning (If Live Testing is Required)

• Conduct a thermal scan to identify hot spots in cables or connections during live testing, ensuring early detection of potential overloads or faulty connections.

Grounding Verification

• Measure grounding resistance to ensure it meets the specified project requirements, essential for safe and stable electrical performance.
• Verify the continuity of shielding and confirm that grounding is present at designated points to effectively reduce EMI and prevent ground loops.

Post-Inspection Rework Verification:

• For any issues identified and addressed during the inspection, perform re-inspection to verify that all corrective actions meet project and safety standards before final sign-off.

Documentation and Reporting

Effective documentation and reporting are essential for ensuring the inspection results are recorded accurately and any deviations are addressed promptly.

Record Findings

• Use standardized forms or software tools to log inspection results meticulously, capturing all test values, observations, and any relevant notes. This creates a reliable reference for future maintenance or audits.

Deviation Marking

• Note any deviations from project design or industry standards. For each deviation, provide detailed documentation and recommend corrective actions to address the issue.
• Document identified issues for follow-up, ensuring they are resolved before final approval.

Drawing Updates

• Update any changes in cable routes, terminations, or configurations in the as-built drawings. Accurate updates ensure future reference aligns with the actual installation.
• Submit updated drawings and documentation to the QA/QC team for review and final approval, ensuring compliance with all project standards.

Additional Considerations

To ensure thoroughness and compliance, additional factors should be considered during the inspection process.

Hazardous Areas

• Follow specific standards such as IEC 60079 and NEC for installations in explosive atmospheres.
• Verify that all cables, glands, and accessories are certified for use in hazardous areas to prevent potential ignition sources.
• Ensure cable entries are properly sealed to maintain the integrity of hazardous area boundaries and to comply with design specifications.

System Integration

• Work with mechanical, electrical, and civil teams to avoid conflicts and interferences with other installations.
• Test integration with control systems like PLCs and DCS to verify compatibility and ensure smooth communication across system interfaces.

Quality Assurance

• Include QA/QC personnel in inspection activities to ensure adherence to project standards and document compliance.
• Arrange for independent, third-party inspections if contractually required, adding an additional layer of quality validation.

Supporting Documentation Forms for Cable Inspection and Testing

Insulation Resistance Test Record (for Instrument Cables Before Installation)

• Document insulation resistance values for all instrument cables before installation to ensure they meet specified standards.

Insulation Resistance Test Record (for Instrument Cables After Installation)

• Record post-installation insulation resistance values to confirm the integrity of cables after laying and termination.

Instrument Cable Glanding and Termination Inspection Form

• Verify and record the quality and security of cable gland installations and terminations to prevent loosening or exposure.

Instrument Cable Trays Inspection Form

• Check that cable trays are installed according to design, properly supported, and free of obstructions or potential hazards.

Instrument Cable Trench Inspection Form

• Inspect cable trenches for proper depth, cleanliness, and secure placement of cables to protect against environmental factors.

Segregation Distance Verification Form (for Instrument and Power Cables)

• Confirm that specified minimum distances between instrument and power cables are maintained to reduce electromagnetic interference.

Material Receiving Report

• Document all received materials, including cable types, quantities, and conditions, verifying they match project specifications.

Over, Shortage, and Damage Report

• Record any discrepancies, shortages, or damages found upon material receipt to facilitate prompt replacement or resolution.

Click here for Instrumentation Shutdown and Turnaround Activity Checklist: A Complete Step-by-Step Procedure

Instrumentation Cable and Wiring Inspection Excel Checklist – Downloadable 

This checklist ensures accurate and compliant inspection of instrumentation cables, enhancing system reliability and preventing potential failures.

Refer the below link to Download the Instrumentation Cable and Wiring Inspection Checklist

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