Electric Heat Tracing

INSTALLATION, MAINTENANCE,

& TROUBLESHOOTING

About These Instrucons

The installaon instrucons within this document

describe the installaon of Thermon trace heang

systems in typical piping applicaons and are suitable for

use with the exible trace heang products listed on this

page.

These instrucons are not intended for mineral- insulated

(MI) trace heaters. Instrucons and documentaon

for other products and applicaons may be found at

www.thermon.com.

For translaons of this document in languages other

than English, please contact Thermon. The English

language version of this document shall govern.

IMPORTANT: To maintain warranty coverage of the

trace heang system, the steps in these installaon

instrucons, including tesng, must be followed and

documented on the Installaon Report (page 12),

wherever required in the text.

Safety and Site Pracce

• Installaon shall be carried out under the supervision

of a qualied person.

• Persons involved in the installaon and tesng of

electric trace heang systems shall be suitably trained

in all special techniques required, including:

• the purpose and funcon of the electrical trace

heang system,

• its associated power supply and control equipment,

and

• how to recognize and avoid the hazards associated

with its operaon and maintenance.

• All personnel shall use all appropriate personal

protecve equipment (PPE), including protecve

clothing, to protect against potenal arc ash and

shock hazards.

• All personnel shall comply with all applicable

safety and health guidelines, including Thermon

requirements, the regulaons outlined in the NEC and

CEC, and EN/IEC/IEEE 60079-30-2 for hazardous areas

(as applicable), and any other applicable naonal and

local electric codes.

• During installaon, the trace heang system

parameters shall be veried. Tests shall be performed

in the eld and documented in the Installaon

Report (page 12) as instructed.

For insulated externally heated surfaces, lower T-class

systems may be obtained by ulizing stabilized designs or

controlled designs using methods described in IEC/IEEE/

EN 60079-30-1, Clause 4.5, using CompuTrace Electric Heat

Tracing Design Soware or by Thermon Engineering.

Types of Heang Cables

Self-Regulang Heang Cables:

BSX™ Self-Regulang Heang Cable

(refer to Form TEP0067)

RSX™ Self-Regulang Heang Cable

(refer to Form TEP0004)

KSX™ Self-Regulang Heang Cable

(refer to Form TEP0072)

HTSX™ Self-Regulang Heang Cable

(refer to Form TEP0074)

USX™ Self-Regulang Heang Cable

(refer to Form TEP0239)

VSX-HT™ Self-Regulang Heang Cable

(refer to Form TEP0208)

Power-Liming Heang Cable:

HPT™ Power-Liming Heang Cable

(refer to Form TEP0011)

Parallel Constant Wa Heang Cable:

FP Parallel Constant Wa Heang Cable

(refer to Form TEP0016)

Series Constant Wa Heang Cables:

TEK™ Series Constant Wa Heang Cable

(refer to Form TEP0021)

HTEK™ Series Constant Wa Heang Cable

(refer to Form TEP0022)

The Naonal Electric Code and Canadian

Electrical Code require ground-fault

protecon be provided for electric heat

tracing .

Trace Heang System Design

• The design of electrical resistance trace heang

systems shall be overseen by persons knowledgeable

of trace heang, following the design methodology

for explosive atmospheres as specied by Thermon

Engineering or

CompuTrace Electric Heat Tracing

Design Soware.

• For insulated externally heated surfaces, lower T-class

systems may be obtained by ulizing stabilized designs

or controlled designs using methods described in IEC/

IEEE/EN 60079-30-1, Clause 4.5, using CompuTrace

Electric Heat Tracing Design Soware or by Thermon

Engineering. The system design parameters, including

the resulng T-class, shall be retained as a record of

system documentaon for each design for at least

as long as the system is in use. The parameters in

the system documentaon shall be checked during

commissioning of the system.

Illustraon A: Typical Trace Heang Installaon

• The stabilized design method may be used for self-

regulang, power-liming, and constant-wa heang

cables without a liming device.

• Series heang cable output and T-rang are

dependent upon several variables, including supply

voltage, cable resistance, and temperature condions.

Complete Electric Heat Tracing System

A complete electric heat tracing system will typically

include the following components

1. Electric heat tracing cable

(self-regulang, power-

liming, parallel constant wa or series constant

wa).

2. Power connecon kit.

3. RTD sensor or control thermostat

4. In-line/T-splice kit (permits two or three cables to be

spliced together).

5. Cable end terminaon.

6. Aachment tape (use on 12” (30 cm) intervals or as

required by code or specicaon).

7. “Electric Heat Tracing” label (peel-and-sck label

aaches to insulaon vapor barrier on 10’ intervals

or as required by code or specicaon).

8. Thermal insulaon

and vapor barrier (by others).

The absence of any of these items can cause a system to

malfuncon or represent a safety hazard.

Notes

1 See Page 3 for trace heater types and references for approvals.

2 Power connecons must be used with correctly-installed cered

enclosures that are suitable for the applicaon (such as Terminator™).

When connecng cered terminals using associated accessories, the

required creepage distances and clearances shall be observed.

3 Temperature control is recommended for all freeze-protecon and

temperature-maintenance trace heang applicaons.

4 All heat-traced lines must be thermally insulated.

Upon Receiving the Trace Heater

1. Make sure that the correct type (including the correct

nominal power output and voltage level) has been

received.

All exible trace heaters, of the types covered in this

document, are printed with the catalog number,

voltage rang and power output (in W/m or W/) on

the jacket. To verify the year of construcon, please

contact Thermon with the batch code number printed

on the trace heater jacket.

2. Record the reel number, reel length, trace heater

type, and nominal power output and voltage in the

Pre-Installaon secon of the Installaon Report

(page 12).

3. Visually inspect cable for any damage incurred

during shipment. Note any observed damage in the

Installaon Report.

4. Perform the Insulaon Resistance (IR) Test, described

on this page, to conrm the trace heater’s electrical

integrity. Record the reading in the Installaon

Report.

5. Store the trace heater in a dry locaon.

Before Installing

• Be sure all piping and equipment to be traced have

been completely installed and pressure-tested.

• Ensure that all surface areas where the trace heater

is to be installed are reasonably clean. Remove any

dirt, rust, and scale with a wire brush. Remove oil and

grease lms with a suitable solvent.

• De-energize power sources before installaon.

• Keep ends of trace heaters and kit components dry

before and during the installaon.

Insulaon Resistance (IR) Tesng

The insulaon resistance (IR) test establishes the

electrical integrity of the trace heater. For the exible

trace heaters covered in this document, the IR test

should be performed with a megger capable of

delivering a voltage of at least 500 Vdc. It is strongly

recommended that polymeric insulated trace heaters

should be tested at 2500 Vdc.

1. If not done already, prepare the conductors of

the trace heater according to the instrucons

accompanying the power and end terminaon kit(s)

provided with the system.

2. Connect the megger’s posive lead to the cable bus

wires, shorted together.

3. Connect the megger’s negave lead to the metallic

braid.

4. Set the megger test voltage to at least 500 Vdc.

5. Energize the megger for 60 seconds.

6. Readings of at least 20 MΩ

are acceptable.

Readings below 20 MΩ usually

indicate that the electrical

insulaon of the trace heater

has been compromised.

Check the trace heater for

signs of physical damage

between the braid and the heang element. Small cuts

or scu marks on the outer jacket will not aect the

megger reading unless there is penetraon through the

braid and dielectric insulaon jacket.

Inial Trace Heater Installaon

• Begin installing the trace heater at the proposed

end-of-circuit locaon, following the guidance in the

isometric system diagrams (if provided).

• Lay out the trace heater on the pipe, at the 4 or 8

o’clock posion (Illustraon B), securing it ghtly

against the pipe with aachment tape. Wrap bands

of tape around the trace heater and pipe at intervals

of 12” (30 cm) or less, keeping the trace heater in

close contact with the pipe.

• If accessibility is a problem, the trace heater may be

installed at the 10 or 2 o’clock posion.

• Refer to Table 1 (page 7) to esmate the number of

rolls of aachment tape required, based on the pipe

length and diameter

• A connuous covering of aluminum foil tape may

also be required under special circumstances,

including:

• where spray or foam

thermal insulaon will be

applied,

• where nonmetallic piping is used, or

Proposed Power

Connecon Locaon

Cable Allowance for

In-Line Heat Sinks

Pipe Support

Proposed

End-of-Circuit

Locaon

Illustraon C: Temporary Installaon

Notes . . .

1. Termination kits to fabricate a heat tracing circuit are not

addressed in detail in these installation procedures. Refer

to installation instructions included with cable termination

kits or contact Thermon for specific instructions to

fabricate heating cable.

Illustraon B: Heang Cable vs. Sensor Locaon

Heang Cable

(Typical)

Pipe Wall

Temperature Sensor

(Typical)

45°

90°

45°

90°

Single Cable Installaon Triple Cable InstallaonDual Cable Installaon

• design requirements dictate the use of

aluminum tape.

• Allow extra length of trace heater for power

connecons, splices, and any in-line heat sinks, such

as valves, anges, and supports (Illustraon C). See

page 7 and page 8 for details on how to

properly install the trace heater at these sites and

the allowance of trace heater required.

• Install temperature sensors at least 90° away from

trace heater locaons.

• CAUTION: For

series constant-wa trace heaters

(HTEK, TEK, TESH), do not allow the heang poron

of the trace heater to touch, cross over, or overlap

itself.

• CAUTION: Do not exceed the trace heater’s

specied minimum bend radius. Refer to product’s

specicaon sheets for the minimum bend radius of

a specic trace heater type.

Notes

1 Table 1 assumes circumferenal bands every 30 cm along the length of the

piping.

2 Verify that the curing temperature of the insulaon is less than the

exposure temperature of the trace heater.

Illustraon D: Pipe Elbow

Illustraon F: Pipe Flange

Heang Cable

Aachment Tape

(Typical)

Illustraon E: Uninsulated Pipe Support

Aachment Tape

(Typical)

Heang

Cable

12” Max.

(30 cm)

Note: Flange allowance will vary

based on method of insulang

ange and adjacent piping.

Support

Length

Aachment Tape

(Typical)

Heang Cable

3” Min.

(8 cm)

3” Min.

(8 cm)

Note . . .

1. Only applicable for pipe ≥ 50mm.

Circuit Layout on Support

Installaon on Elbows, Pipe Supports, and Flanges

• Elbows: Locate the trace heater on the outside

radius of the elbow (Illustraon D). Secure the trace

heater to the pipe with aachment tape on each

side of the elbow.

• Pipe Supports: For uninsulated pipe supports, allow

twice the length of the support, plus an addional 40

cm of trace heater. Install the trace heater in a loop,

following Illustraon E as a guide. Insulated pipe

supports do not require addional length of trace

heater.

• Flanges: Loop the trace heater around the pipe

on each side of, and adjacent to, the ange

(Illustraon F). Be sure to keep the trace heater in

close contact with the ange throughout the length

of the bend.

Refer to Table 2 (page 8) for typical ange allowances.

Table 1: Aachment Tape (Value Represents Approximate Linear Pipe Length Allowance Per Roll)

Tape

Length

Pipe Diameter in Inches

½"-1" 1¼" 1½" 2" 3" 4" 6" 8" 10" 12" 14" 16" 18" 20" 24" 30"

36 yd 130' 115' 110' 95' 75' 65' 50' 40' 35' 30' 26' 23' 21' 19' 16' 13'

60 yd 215' 195' 180' 160' 125' 105' 80' 65' 55' 50' 43' 38' 35' 31' 27' 22'

Illustraon G: Typical Valve Detail

Installaon on Valves and Pumps

• Valves, pumps, and other miscellaneous equipment

require addional passes of trace heater to oset the

increased heat loss that occurs at these sites.

• Refer to the isometric system drawings, provided by

Thermon Engineering, for allowances specic to each

line and circuit.

Allowances for typical valves and pumps are provided

in Table 2.

• Install the trace heaters using a looping technique,

using Illustraons G and H as a guide, such that the

valve or pump may be removed for required service

and maintenance.

• Keep the trace heater in close contact with the pipe

and heat sink areas, to compensate for addional heat

loss.

Illustraon H: Typical Pump Detail

Heang Cable Serpenned on Pump

Single Circuit Layout on Valve

Mulple Circuit Layout on Valve

Heang Cable #1

Heang Cable #2

Heang Cable #3

Heang Cable #1

Heang Cable #3

Heang Cable #2

Heang Cable #1

Heang Cable #3

Heang Cable #2

Single Circuit Layout on Pump

Mulple Circuit Layout on Pump

Heang Cable #1

Heang Cable #2

Heang Cable #3

Heang Cable Serpenned on Valve

Table 2: Valve and Pump Allowances

Pipe

Size

Valve Allowance Pump Allowance

Flange

Allowance

Screwed or

Welded

Flanged Buery Screwed Flanged

½" 6" 1' 0 1' 2' 1’ 3"

¾" 9" 1' 6" 0 1' 6" 3' 1’ 6"

1" 1' 2' 1' 2' 4' 1’ 6”

1¼" 1' 6" 2' 1' 3' 4' 6" 2’ 0"

1½" 1' 6" 2' 6" 1' 6" 3' 5' 2’ 0"

2" 2' 2' 6" 2' 4' 5' 6" 2’ 3"

3" 2' 6" 3' 6" 2' 6" 5' 7' 2’ 3"

4" 4' 5' 3' 8' 10' 2’ 9"

6" 7' 8' 3' 6" 14' 16' 3’ 3"

8" 9' 6" 11' 4' 19' 22' 3’ 9"

10" 12' 6" 14' 4' 25' 28' 4’ 3"

12" 15' 16' 6" 5' 30' 33' 5’ 0"

14" 18' 19' 6" 5' 6" 36' 39' 5’ 6"

16" 21' 6" 23' 6' 43' 46' 6’ 0"

18" 25' 6" 27' 6' 6" 51' 54' 6’ 6"

20" 28' 6" 30' 7' 57' 60' 7’ 3"

24" 34' 36' 8' 68' 72' 8’ 3"

30" 40' 42' 10' 80' 84' 10’ 0"

Note

1. The valve allowance given is the total amount of addional cable to be

installed on the valve. If mulple tracers are used, total valve allowance

may be divided among the individual tracers. The total valve allowance

may be alternated among tracers for mulple valves in a heat trace circuit.

Allowances are for 150 pound valves. More cable is required for higher

rated valves. Refer to heat trace isometric drawing for project specic

allowances.

Compleng the Trace Heater Installaon

1. Secure the end-of-circuit terminaon kit and work

back toward the power supply (Illustraon I).

2. Keep the trace heater in secure contact with the pipe,

using bands of aachment tape at least every 30 cm.

3. Secure any required temperature sensors to the pipe

using aachment tape.

4. Complete any required splice connecons in

accordance with the installaon instrucons provided

with the splice kit.

5. Install any power connecon kits in accordance with

the detailed installaon instrucons provided with the

kit.

Installing Thermal Insulaon

Properly installed and well-maintained thermal

insulaon is crical to the performance of the trace

heang system. Without proper insulaon, heat losses

are generally too high to be oset by a convenonal heat

tracing system.

1. Properly insulate all heat sinks, including pipe

supports, hangers, anges, and in most cases, valve

bonnets.

2. Install a protecve vapor barrier over the insulaon,

regardless of the type or thickness of insulaon

used. The vapor barrier protects the insulaon from

moisture intrusion and physical damage and ensures

the proper performance of the trace heang system.

3. Seal all penetraons around the vapor barrier.

4. Aer ensuring that the insulaon is weather-ght,

document the compleon of the insulaon in the

Aer Installaon of Thermal Insulaon secon of the

Installaon Report

(page 12).

Aer Installing Thermal Insulaon

The presence of trace heaters shall be made evident

by posng of cauon signs or markings at appropriate

locaons and/or at frequent intervals along the circuit.

1. Apply the provided peel-and-sck “Electric Heat

Tracing - Cauon” labels along the pipe, on the

outermost surface of the thermal insulaon or vapor

barrier, at intervals of 3 m or less.

2. Apply the cauon labels at any other appropriate

locaons, such as valves.

6. Connect the metallic braid of the trace heater to a

suitable earthing/ground terminal.

7. Before compleng the power connecons, perform

an Insulaon Resistance (IR) Test (page 5) and record

the result in the Aer Installaon secon of the

Installaon Report (page 12). The recorded value

shall not be less than 20 MΩ.

8. Record the line number and all other associated

circuit informaon in the Aer Installaon secon of

the Installaon Report.

Illustraon I: Final Cable Aachment

Proposed End of Circuit

Aachment Tape

Proposed Power Supply

Installaon Guidelines for Fire Protecon Systems

1. Where above ground water-filled supply pipes, risers,

system risers or feed mains pass through open areas, cold

rooms, passageways, or other areas exposed to freezing

temperatures, the pipe shall be protected against freezing

in accordance with NPFA 13, "Standard for the Installaon of

Sprinkler Systems".

2. Thermon's BSX Self-Regulang Heang Cables are approved

for use on Fire Protecon System Piping feed mains, risers, and

cross mains. This applicaon approval includes piping which

connects between buildings in unheated areas, piping located

in unheated areas or piping through coolers or freezers. As

with all heat traced piping systems, thermal insulaon is

required to ensure the heang system can compensate for

heat losses.

3. In accordance with IEEE 515.1 guidelines, the use of ambient

sensing control with low temperature and continuity

monitoring as a minimum for all re protecon piping heat

tracing systems is required. Thermon recommends the

use of the Thermon TCM2 electronic controller for these

applicaons, having capability of annunciang the following

faults/alarms locally as well as remotely:

• Ground / Earth fault

• Low temperature

• High temperature

• Sensor failure

• Controller failure

• Low current

• Circuit fault

• High temperature limit controller, if provided.

4. Pipe secons that lie in dierent ambient condions (e.g.

inside the building (heated areas) and outside the building)

should not be under the same temperature control zone.

5. The heat tracing system shall be designed to maintain the

pipe temperatures between 4°C and 38°C, or if necessary for

the installaon, an addional 'Hi Temp' limit sensor should be

included to limit the runaway pipe temperature within 55°C

or 8°C below the sprinkler temperature rang, whichever is

lower. A low-temperature alarm with contacts for a remote

annunciaon shall be provided for each re sprinkler line trace

heang circuit with a set-point of 2°C.

6. The alarms of sprinkler system temperature/electrical

control shall be connected to a re detecon alarm system

monitoring.

7. Both of the two basic sprinkler system types i.e. wet (where

the branch lines are always lled with water) and dry type

(where the sprinkler head/sensor acvates the upstream

control valve) require heat tracing for the branch lines up to

the sprinkler head. In case of dry type, the tracing is meant

to keep the empty branch pipes above freezing point, so that

Feed Main

Branch Line

End

Terminaon

Cross Main

RTD

Riser

PCS-COM

Heater

Thermon TCM2

(Recommended)

PCA-COM

Cold Room

Condioned

Area

THE NFPA DEFINES THE FOLLOWING:

Branch Lines—The pipes in which the sprinklers are placed, either

directly or through risers.

Cross Mains—The pipes supplying the branch lines, either

directly or through risers.

Feed Mains—The pipes supplying cross mains, either directly

or through risers.

Risers—The vercal supply pipes in a sprinkler system.

when upstream control valve operates the pipe body does not

cool down the incoming water.

8. Trace heating systems for fire sprinkler systems shall be

permanently connected to the power supply.

9. The heat tracer braid shall be connected to earth / ground

terminal at every terminaon and suitable external grounding.

10. If backup power is being provided for the building electrical

systems, it shall also provide backup power supply for the

trace heang system or equivalent.

Final Inspecon

1. Aer installing the thermal insulaon and vapor

barrier BUT BEFORE ENERGIZING THE CIRCUIT,

repeat the IR test to verify that the trace heater has

not been damaged during installaon. Record the IR

value

in the Aer Installaon of Thermal Insulaon

secon of the Installaon Report (page 12).

2. For Series Heang Cables, measure the electric loop

resistance and record the resistance values

in the

Installaon Report.

3. Ensure that all juncon boxes, temperature

controllers, cable glands, etc., are properly secured.

4. If a temperature controller is used, force the circuit on

and energize the circuit at the rated voltage.

5. Aer 5 minutes, measure the voltage, current, pipe

temperature, and ambient temperature. Record these

values in the Final Commissioning secon of the

Installaon Report.

6. If a control device is used, verify its sengs to ensure

that the maximum surface temperature does not

exceed the system T-rang, in accordance with IEC/

IEEE/EN 60079-30-1, Clause 4.

Documentaon Retenon

The trace heang system documentaon shall be

retained for each trace heang circuit for as long as the

system is in use. This includes:

• System Design Parameters And T-Class

• Isometric Circuit Diagrams

• Maintenance Records

• Operang History

• These Instrucons

• All Other Documentaon Provided By Thermon

Circuit Protecon Requirements

• Each branch circuit must use over-current protecon

that isolates all appropriate power conductors from

the supply (typically circuit breakers).

• Ground fault equipment protecon is required for

each circuit.

• For typical installaons (with TT and TN grounding

systems), the means of protecon must include a

residual current protecve device for each branch

circuit.

• For xed-level earth/ground-fault circuit interrupters,

a minimum 30 mA trip level is recommended. The

preferred trip level for adjustable devices is 30 mA

above any inherent capacive leakage characterisc of

the heater, as specied by Thermon Engineering.

• Where condions of maintenance and supervision

ensure that only qualied persons will service the

installed systems, and connued circuit operaon is

necessary for the safe operaon of the equipment

or processes, ground-fault detecon without

interrupon is acceptable if alarmed in a manner to

assure an acknowledged response.

• For IT grounding systems, a means of protecon

against ground faults is required that includes an

electrical insulaon monitoring device that shall

disconnect the supply whenever the electrical

resistance is not greater than 50 ohms/volt of rated

voltage.

Installaon Report

Project Informaon

Project No. Installer

Unit No.

Customer Reference No. Inspector

Thermon Reference No.

Pre-Installaon

Reel No. Insulaon Resistance (IR)

Reel Length

m/ Single-Phase: MΩ/GΩ

Trace Heater Type

3-Phase

(for Series

Trace Heaters):

MΩ/GΩ

Power Output (nom.)

W/m/W/

MΩ/GΩ

Voltage (nom.)

MΩ/GΩ

Notes Tested By/Date

Witnessed By/Date

Aer Installaon

Line No. Braid Connected to Ground?

Equipment No. Unused Entries Plugged O?

Circuit/Heater No. Insulaon Resistance (IR)

Circuit Switch No.

Single-Phase: MΩ/GΩ

Thermostat No.

3-Phase

(for Series

Trace Heaters):

MΩ/GΩ

Juncon Box No. L

MΩ/GΩ

Panel No. L

MΩ/GΩ

Breaker No.

Trace Heater Line Length

m/

Notes Tested By/Date

Witnessed By/Date

Aer Installaon of Thermal Insulaon

Insulaon Weather-Tight? Insulaon Resistance (IR)

Cauon Labels Placed?

Single-Phase: MΩ/GΩ

Electrical Loop

Resistance

(for

Series Trace Heaters)

L-L

3-Phase

(for Series

Trace Heaters):

MΩ/GΩ

-L

MΩ/GΩ

-L

MΩ/GΩ

-L

Notes Tested By/Date

Witnessed By/Date

Final Commissioning

Perform nal measurements aer energizing circuit for 5 minutes.

Ambient Temperature

°C/°F

Voltage

Pipe Temperature

°C/°F

Current

Notes Tested By/Date

Witnessed By/Date

NOTE: All Insulaon Resistance (IR) values shall be at least 20

MΩ for a successful installaon.

Troubleshoong Guide

This troubleshoong guide aims to help to diagnose and

resolve many issues on-site.

Many problems with electric trace heang systems can

be aributed to two causes:

• Wet, damaged, or missing insulaon. Visually inspect

the insulaon along the enre length of the circuit,

making sure that it is intact and dry throughout.

• Physical damage incurred from recent repairs and

maintenance to any in-line or nearby equipment.

Symptom Possible Cause Remedy

No heat/no current • Loss of power/voltage • Check the circuit breaker and electrical

connecons

• Controller setpoint too low • Verify/adjust setpoint

• High-temperature limit switch acvated • May require manual reset to re-enable

trace heang circuit

• “Open” series heang circuit • Repair or replace circuit

• Controller failure • Repair sensor or controller

Before maintenance, repair, or modicaon

CAUTION: Consult the trace heang system

documentaon prior to maintenance, repair, or

modicaon.

1. Idenfy the circuit or equipment to be de-energized

and all possible sources of electrical energy supplies

to the specic circuit and equipment.

2. De-energize all power sources.

3. Apply lockout/tagout devices according to established

procedures.

4. Test for the absence of voltage with an approved

voltmeter (where the voltmeter is tested on a known

circuit voltage prior to and immediately following

applicaon).

5. For protecon against the accidental energizing of

supply conductors, apply temporary jumpers rated

for the available fault duty between each supply

conductor and earth/ground.

NOTE: In the event of an ground fault or over-current

interrupon, devices shall not be reset unl the cause of

the trip has been invesgated by qualied personnel.

Aer maintenance, repair, or modicaon

1. Test the operaon of each aected circuit.

2. The insulaon resistance of the trace heater shall be

measured and recorded and shall not be less than 20

MΩ.

3. Visually verify that all circuit-disconnect devices are

open before reconnecng power.

Maintenance and Repair

• Once the system has been successfully installed, an

ongoing prevenve maintenance program should be

implemented, using qualied personnel. The trace

heang system should be inspected and tested on a

regular basis, at least once per year.

• Keep records of the operang and maintenance

history for each circuit, including all test results

performed during maintenance and inspecon.

Record-keeping during scheduled maintenance will

help to establish a “normal” range of operaon.

Insulaon resistance readings that deviate from the

normal range may indicate problems with a circuit.

• If the system fails any test, refer to the

troubleshoong guide below to address the issue.

De-energize the aected circuits and make the

necessary repairs immediately.

Other possible causes are listed below, with their

symptoms and potenal remedies.

If any circuit is suspected to be damaged, de-energize

the circuit and perform the Insulaon Resistance Test

outlined on page 5.

Readings below 20 MΩ indicate that

the trace heater may be physically damaged.

Symptom Possible Cause Remedy

Low system temperature • Controller setpoint too low • Verify/adjust setpoint

• Temperature sensor located too close

to trace heater or other heat source;

may be accompanied by excessive

cycling of control relays/contacts

• Relocate sensor

• Insulaon material and/or thickness

dierent than designed

• Replace insulaon; increase insulaon

thickness (if dry); review design

• Ambient temperature lower than

designed

• Install higher-output trace heater; increase

insulaon thickness; review design

• Low voltage (check at power

connecon point)

• Adjust voltage to meet design

requirements

Low temperature in

secons

• Wet, damaged, or missing insulaon • Repair or replace insulaon and barrier

• Trace heater damaged • Repair or replace secon; splice kits are

available from Thermon

• Heat sinks (valves, pumps, pipe

supports, etc.)

• Insulate heat sinks or increase passes of

tracing on heat sinks

• Signicant changes in elevaon along

length of the heat-traced pipe

• Consider dividing heang circuit into

separate, independently controlled

segments

High system

temperature

• Controller “on” connuously • Adjust setpoint or replace sensor

• Controller fails with contacts closed • Replace sensor or controller

• Sensor located on uninsulated pipe or

too close to heatsink

• Relocate sensor to an area representave

of condions along length of pipe

• Backup heang circuit controller “on”

connuously

• Adjust setpoint or replace backup

controller

Excessive cycling • Temperature sensor located too close

to trace heater or other heat source;

may be accompanied by low system

temperature

• Relocate sensor

• Ambient temperature near controller

setpoint

• Temporarily alter controller setpoint

• Connected voltage too high • Lower voltage

• Trace heater output too high

(overdesign)

• Install lower-output trace heater or lower

the voltage

• Controller dierenal too narrow • Widen the dierenal or replace controller

to avoid premature contact failure

Temperature variaons

along pipe

• Inconsistent trace heater installaon

along pipe

• Check consistency of trace heater

installaon, especially at heat sinks

• Inconsistent trace heater performance • Compare calculated power per unit length

(W x A/length) for the measured pipe

temperature with designed trace heater

output for the same temperature; regional

damage to trace heater can cause paral

failure

• Unancipated ow paerns or process

operang temperatures

• Redistribute heang circuits to

accommodate exisng ow paerns;

conrm process condions

Notes

1 Flexible, polymer-jacketed trace heaters (such as those covered in this document) may be eld-spliced. Mineral-insulated (MI) trace heaters typically require

replacement.

2 Mechanical thermostat sensors cannot be repaired or replaced. RTD and thermocouple sensors may be replaced. Some controllers have replaceable contacts/

relays or may require a manual reset if a “trip-o” condion was detected.

3 Before making any changes to system parameters, consult Thermon for the impact on trace heater performance.

Corporate Headquarters:100 Thermon Dr • PO Box 609 San Marcos, TX 78667-0609 • Phone: 512-396-5801 • 1-800-820-4328

For the Thermon oce nearest you visit us at . . . www.thermon.com

Form PN50207-0220