Daily Visual Inspection
Inspect the heating cable outer sheath at least once a week for damage, cracking, or aging such as PE or PTFE material becoming hard or discolored. Increase inspection frequency in winter or high-humidity environments. Confirm that joints are well sealed with no water ingress or corrosion. Check if fixing clamps are loose, or if the cable is sagging or tangled. Early detection of sheath damage prevents moisture ingress that can cause insulation failure and system shutdown.
Electrical Performance Testing
For insulation resistance testing, use a megohmmeter at the 500V range. After disconnecting the power, measure the insulation resistance between the cable core and the outer sheath. The standard value should be at least 20 megohms, or at least 1 megohm in humid environments. A drop in insulation resistance may indicate water ingress due to a damaged outer sheath and requires immediate investigation. For ground continuity testing, confirm reliable connection of the cable grounding wire with grounding resistance of 4 ohms or less per the Code for Construction and Acceptance of Grounding Devices for Electrical Installations.
Temperature Monitoring
Use an infrared thermal imager to scan the cable surface temperature. The temperature should be uniform and meet design requirements, with pipe insulation temperature maintained at 5 degrees Celsius or above. Abnormal temperature rise such as localized temperatures exceeding 80 degrees may be caused by overload or poor contact and requires immediate shutdown and inspection. Calibrate thermostat accuracy once a year with error no more than plus or minus 2 degrees to ensure the automatic start and stop function works properly.
Quarterly Deep Maintenance
Clean the cable surface quarterly by wiping dust with a dry cloth to prevent dust accumulation from affecting heat dissipation. If the outer sheath is contaminated with oil, wipe it with a neutral detergent. The use of organic solvents such as gasoline is strictly prohibited. Check if power joints and T-branch joints are loose and tighten to the specified torque, typically 0.5 to 1 newton-meter.
Annual Maintenance Procedures
Perform a full system test annually by simulating a low-temperature environment such as minus 20 degrees to verify that the cable heating capacity meets the standard. Check if the temperature control system and leakage protection devices are functioning normally. Replace heavily aged cable segments such as those with brittle outer sheath or broken core wires. Stock up on common spare parts including joints, thermostats, and sealant to minimize downtime when replacements are needed.
