The following information is intended to assist in troubleshooting electric heat tracing systems. The
primary objective is to provide an enhanced understanding of the elements of a successful heat tracing
installation. Of these elements, one of the most important is the thermal insulation.
Before calling the heat tracing vendor, make a visual inspection of the installation; perhaps the thermal
insulation is wet, damaged or missing. Also consider the possibility that repairs or maintenance of in-line
or nearby equipment may have resulted in damage to the heat tracing equipment. These are common
causes of tracing problems which are often overlooked. Other possible causes are listed below with their
symptoms and remedies.
If an electric heat tracing circuit is suspected to be damaged, a dielectric insulation resistance (megger)
test should be performed using a 2500 Vdc megohmmeter for polymer-insulated heating cables or 1000
Vdc for MI cable. Periodic testing with accurate records will establish a “normal” range of operation (refer
to the Inspection Report Form on page 3). Dielectric insulation resistance readings which deviate from
the normal range can quickly reveal a damaged circuit.
Please select from the symptoms below:
Notes . . .
1. Flexible, plastic-jacketed heating cables may be field-spliced; MI cables usually require replacement.
2. Mechanical thermostat sensors cannot be repaired or replaced; RTD or thermocouple sensors can be replaced. Some controllers have replaceable
contacts/relays or may require a manual reset if a “trip-off” condition on the heating circuit was detected.
3. The operation of most electric heat tracing cables is dramatically affected by changes in the supply voltage. Before making any changes, consult the
cable manufacturer with information on the alternate voltages available. Otherwise, cable failure and/or an electrical safety hazard may result in