Your heat tracing system is an indispensable part of your operation, ensuring equipment and pipes remain at optimal temperatures constantly. But, like any technology, issues can crop out, hampering productivity. Therefore, knowing how to conduct fault finding is crucial to maintaining a functional heat tracing system.

However, please approach with caution when fault finding on a heat tracing cable, as there are various steps involved in conducting proper field maintenance. We recommend dividing the task into three sections in the following order – the power cable, the heat tracing cable, and the thermostats – to ensure successful fault identification, thus enabling the seamless operation of your heat tracing system.

Learn More: How To Troubleshoot Your Electrical Heat Trace System

Power cable

For safety reasons, you should always disconnect the power cable in the panel and insulate the wires first. Open the power junction box in the field and disconnect any heat tracing cable from the terminals. Afterwards, you can proceed with the megger test for the power cable located between the junction box and the panel.

Should you encounter a low IR value (below 10M ohm), please verify and ensure that no intermediate marshaling box is installed. If so, disconnect the power cables and check each section. Do not neglect to perform a “loop check” on each power cable. Repair or replace the power cable where necessary if there is a defect.

Heat tracing cable

Perform a megger test for the heat tracing cable(s) from the power junction box. In the event of a low IR value(below 10M ohm), you can detect where the fault lies through the following steps.

Step 1: Check the heat tracing cable

Firstly, ensure the heat tracing cable comprises only one section. However, if there are T-boxes installed, please disconnect the heat tracing cables from the T-box and megger the individual sections. Subsequently, inspect the heat tracing cable from end to end to verify it is not damaged. 

As most of the heat tracing cable is covered by thermal insulation, the probability of detecting damage will be low. So, try to recall when and where the heat tracing cable was worked on and if there were any instances of damage to the heat tracing cable at that time. Another option is to use a hand-held cable fault locator to send an electrical pulse to the heat tracing cable.

Step 2: Check the junction box

Sometimes, the defect may lie in the terminals of the junction box. For instance, water in the box can create an electrical leak path, causing the ELCB to trip. So, ensure the junction box is adequately sealed, and there are no signs of moisture in the box. Another possible explanation is that the cables in the terminals may have poor or no connection due to incorrect work done during stripping and connecting.

Step 3: Check the end seal

In rare instances, faults in end seals can occur, causing a defect. For example, incorrect work may result in moisture or water entering the end seal. When this happens, please replace the end seal immediately.

Thermostats

Lastly, use a voltmeter to verify that the internal relay of the mechanical thermostat is still switching on and off correctly. Replace it if there is a defect. Conversely, when inspecting an electronic thermostat, you must take additional safety precautions since there is voltage applied on the heat trace thermostat.

You can simulate a low temperature with a resistor or adjust the thermostat set point higher to turn on the electronic thermostat. Subsequently, check that the contactor inside is switched on with a voltmeter. Ensure you return the set point to its original value once you are done with the testing.

Please note that the steps we shared are a brief overview of how to conduct fault finding on your heat tracing cables. We recommend following the specifications provided by the manufacturer and observing work safety protocols at all times during the inspection. If you are unsure how to proceed, contact a professional to conduct the examination.

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