Thermon MIQ Mineral Insulated Heating Cable v.1 - Manual (Page 9)

INSTALLATION PROCEDURES
Circuit Protection Requirements . . .
1. Over-current protection (typically circuit breakers) is
required for each branch circuit. This protection must
isoloate all power conductors from the supply.
2. For typical installations (with TT and TN grounding
systems), a means of protection against earth faults
is required that includes a residual-current protective
device for each branch circuit. For fi xed-level ground-
fault circuit interrupters (such as GFCI circuit breakers),
a minimum 30 mA trip level is recommended. The
preferred trip level for adjustable devices is 30 mA
above any inherent capacitive leakage characteristic
of the heater as specifi ed by the heat tracing supplier.
Where conditions of maintenance and supervision
ensure that only qualifi ed persons will service the
installed systems, and continued circuit operation is
necessary for the safe operation of the equipment or
processes, earth-fault detection without interruption
is acceptable if alarmed in a manner to assure an
acknowledged response.
3. For IT grounding systems, a means of protection
against earth faults is required that includes an electrical
insulation monitoring device that shall disconnect the
supply whenever the electrical resistance is not greater
than 50 ohms/volt of rated voltage.
Thermal Insulation . . .
1. The need for properly installed and well-maintained
thermal insulation cannot be overemphasized. Without
insulation, heat losses are generally too high to be offset
by a conventional heat tracing system.
2. In addition to piping and in-line equipment such as
pumps and valves, all heat sinks must be properly
insulated. This includes pipe supports, hangers, fl anges
and, in most cases, valve bonnets.
3. Regardless of the type or thickness of insulation used, a
protective barrier should be installed. This protects the
insulation from moisture intrusion, physical damage and
helps ensure the proper performance of the heat tracing
system. Seal around all penetrations through the thermal
insulation.
4. After the installation of the thermal insulation and
weather barrier but BEFORE ENERGIZING THE
HEATING CIRCUIT, the megohmmeter test should be
repeated. The measured value should not be less than
5 megohms. This should call attention to any damage
to the heating cable that may have occurred during the
insulation installation. (Record 3, Checklist on Page 9)
5. Apply caution labels to insulation weather barrier at
required intervals along pipe.
Final Inspection and Documentation . . .
1. It is recommended that the circuit be temporarily
energized so that the volts, amps, pipe temperature and
ambient temperature may be recorded. This information
may be of value for future reference and should be
maintained for the historical operating data log.
(Record 4, Checklist on Page 9)
2. A sample historical operating data log form is
included in the Electric Heat Tracing Maintenance and
Troubleshooting Guide, Thermon Form TEP0066.
3. Stabilized design can be used for MIQ heating cables
without a limiting device to determine the T-class
through the use of the Thermon CompuTrace software
or Thermon Engineering.
4. The maximum temperatures provided by Thermon’s
CompuTrace software and by Thermon engineering are
calculated to the methods and requirements of
EN-IEC 62086-2 and EN-IEC 60079-30.
5. If stabilized design is used, the end user must record the
system parameters and the area T-class, and keep these
records for the time the heating cable is in operation.
6. Inspect system on a regular basis at least once per
year. Record all information after conducting test. If the
system fails any test, refer to Thermon’s Maintenance
and Trouble Shooting Guide for assistance. De-energize
circuits affected and make the necessary repairs
immediately.
7. Verify the setting of the maximum control device, if
provided to limit the T-rating for the circuit design, to
insure it limits the maximum surface temperature to be
in compliance with clause 4.4.3 of EN-IEC 60079-30-1.
Maintenance and Repair . . .
1. Refer to form TEP0066-Electric Heat Tracing
Maintenance and Trouble Shooting Guide.
Due to the risk of electrical shock, arcing and fi re caused by
product damage or improper usage installation or maintenance,
a earth/ground-fault protection device is required for all heat
tracing circuits. Bond the metal sheath of the heat tracing cable
to a suitable earth terminal.
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