IEC 60068-2-5 - Environmental testing - Part 2-5: Tests - Test Sa: Simulated solar radiation at ground level and guidance for solar radiation testing EN 60068-2-5 - IEC 60519-1 - Safet
General
Electrical resistance trace heating systems must be designed and built to guarantee electrical, thermal, and mechanical durability, ensuring reliable performance Under normal usage conditions, these systems should pose no risk to users or their environment.
Trace heaters designated for low-risk mechanical damage areas undergo modified impact tests (5.2.4 and 5.2.5) and a reduced force in the deformation test (5.2.6) These heaters must be clearly marked as outlined in Clause 7.
Trace and surface heaters can include extra mechanical protection to comply with the standard when provided as a prefabricated assembly, and they must be labeled according to the specifications outlined in Clause 7, item g).
Trace heating equipment intended for use in contact with potable water shall be constructed of materials that meet relevant toxicity requirements
The manufacturer must specify the maximum withstand temperature in degrees Celsius Additionally, the materials utilized in the trace heater or surface heater should endure temperatures that are 20 K higher than the declared maximum withstand temperature, as tested according to section 5.2.11.
Electrically conductive covering
Trace and surface heaters must feature a uniformly distributed electrically conductive covering that encompasses at least 70% of the surface area Additionally, surface heating units should be designed so that the electrically conductive covering is positioned opposite the surface intended for heating.
Electrical circuit protection requirements for branch circuits
Trace heating systems must meet essential requirements, including the ability to isolate all line conductors from the power supply, over-current protection for each branch circuit, and Earth-fault protection for every branch circuit.
Trace heater branch circuit protection must effectively interrupt both earth faults and short-circuit faults It is essential to utilize an earth-fault protective device or a controller equipped with earth-fault interruption capabilities, with a recommended nominal trip rating of 30 mA However, in situations where capacitive leakage may cause nuisance tripping, devices with a trip current not exceeding 300 mA are permissible These protective devices should be used alongside circuit overcurrent protection In cases where maintenance is conducted by qualified personnel and uninterrupted circuit operation is critical for safe equipment functioning, earth-fault detection without interruption is acceptable, provided that an alarm system ensures a prompt and acknowledged response.
Temperature requirements
A trace heating system must be designed to ensure that the surface temperature of the trace or surface heater remains below its maximum withstand temperature and any specified system temperature ratings under all foreseeable conditions This can be accomplished through a stabilized or controlled design approach.
In stabilized design applications, the maximum surface temperature of trace or surface heaters, without thermostatic control, must utilize either the systems approach outlined in section 5.2.13.2 or the product approach described in section 5.2.13.3.
The surface temperature obtained through controlled design is based on energy limitation by temperature controllers or limiting devices
Type tests – General
All trace and surface heaters must comply with the type test requirements outlined in section 5.2 Additionally, those designed for applications specified in Clause 1, items b), c), and d) are required to meet the standards set forth in sections 5.3, 5.4, and 5.5, respectively.
Samples of trace heaters selected for testing shall be at least 3 m in length, unless otherwise specified
Integral components must undergo the same type testing as the trace or surface heater, unless specified otherwise Other system components, not classified as integral, should be assessed based on the applicable standards related to their design and functionality.
Tests shall be conducted at a room temperature between 10 ºC and 40 ºC unless otherwise specified
Separate samples shall be used for each test unless otherwise specified These shall be prepared in accordance with the manufacturer's recommendations.
Type tests – All applications
The dielectric test shall be performed on trace heaters or surface heaters in accordance with Table 1
Table 1 – Test voltages for the dielectric test
For single conductor series trace heaters or surface heaters the voltage shall be applied between the conductor and the metallic sheath, braid, screen or equivalent electrically conductive covering
For multi-conductor series trace heaters or surface heaters, voltage must be applied between the connected conductors and the metallic sheath, braid, screen, or equivalent conductive covering Additionally, voltage should be applied between each conductor individually while the other conductors remain connected together.
For parallel trace heaters or surface heaters the voltage shall be applied between the conductors connected together and the metallic sheath, braid, screen or equivalent electrically conductive covering
The dielectric test can also be performed by immersing trace or surface heaters in tap water at room temperature, which typically has a resistivity of 50,000 Ω·cm During the test, a voltage is applied between the heating conductors and the water.
The rate of rise shall be neither less than 100 V/s nor more than 200 V/s and maintained for
1 min at the specified test voltage without dielectric breakdown The test voltage waveform shall be essentially sinusoidal, with a frequency of 45 Hz to 65 Hz
For type tests 5.2.4 to 5.7.1 concerning MI trace heaters, the required test voltage specified in section 5.2.1 is adjusted to 2U + 500 V a.c for heaters rated at or above 30 V a.c., and to √2U + 500 V d.c for those rated at or above 60 V d.c.
When determining U, the correct use of phase-to-phase or phase-to-neutral voltage levels shall be considered
The electrical insulation resistance shall be measured on the test sample(s) prepared in accordance with 5.1 after the dielectric test specified in 5.2.1
For single conductor series trace heaters or surface heaters, it is essential to measure the resistance of the electrical insulation between the conductor and the metallic sheath, braid, screen, or any equivalent electrically conductive covering.
For multi-conductor series trace heaters or surface heaters with electrically insulated conductors, it is essential to measure the resistance of the electrical insulation This measurement should be taken between the connected conductors and the metallic sheath, braid, screen, or equivalent conductive covering, as well as between each individual conductor and the remaining connected conductors.
For parallel trace heaters or surface heaters, it is essential to measure the resistance of the electrical insulation between the connected conductors and the metallic sheath, braid, screen, or any equivalent electrically conductive covering.
The insulation resistance shall be measured by means of a d.c voltage of at least 500 V The measured value shall be not less than 50 MΩ
Flammability tests are required for trace heaters and surface heaters, including those with integral components, ensuring compliance across all sizes These tests must be conducted in a draft-free environment within a flame chamber or fume hood with a minimum volume of 0.5 cubic meters For trace heaters, samples should be at least 450 mm long and positioned vertically, while surface heaters must adhere to the same length requirement with a maximum width of 80 mm.
To ensure accurate testing, wrap a gummed unbleached paper indicator around the sample, allowing it to extend 20 mm beyond the sample's edge Position the paper indicator 250 mm above where the inner blue cone of the flame meets the sample Additionally, place a layer of dry, pure surgical cotton, no deeper than 6 mm, beneath the sample, maintaining a distance of 250 mm from the cotton to the flame application point.
For testing, a laboratory burner compliant with ASTM D 5025-05 must be utilized, with the gas flame calibrated according to ASTM D 5207-09 The fuel options include methane, propane, or natural gas, all of which should meet the calibration standards outlined in ASTM D 5207-09 The flame height should be set to 130 mm, featuring a 40 mm inner blue cone, and the burner must be tilted at a 20° angle from vertical The flame should be directed at the heating device so that the tip of the inner blue cone touches the specimen 250 mm below the unbleached paper indicator and approximately 150 mm from the sample's bottom For termination assemblies, the flame must contact the material at its most vulnerable point, while clamps supporting the sample should be positioned above the paper indicator and at least 80 mm below the flame application point.
The flame must be positioned so that the vertical plane of the burner tube's major axis is perpendicular to the sample For surface heaters, the flame is directed at the horizontal midpoint, with the unbleached paper indicator placed vertically above the flame, as illustrated in Figure 1 The flame is applied for 15 seconds, followed by a 15-second removal, repeating this process for a total of five applications.
The test results are deemed satisfactory if the sample does not sustain combustion for over 1 minute after the fifth flame application, does not burn more than 25% of the extended unbleached paper indicator, and does not ignite cotton from falling burning particles.
Figure 1a – Height of natural gas flames Figure 1b – Vertical plane at right angles to sample under test Key
2 Support 5 Dry pure surgical cotton
Figure 1 – Flammability test Room temperature impact test
Electric trace heaters and surface heaters are typically protected by thermal insulation, providing mechanical safety in most applications However, there are instances where this protection is absent, such as during installation prior to insulation application or when the heaters extend from insulation into junction boxes or exposed outdoor areas.
A sample approximately 200 mm in length is placed on a rigid flat steel plate (approximately
The sample, weighing 21 kg and measuring 195 mm × 195 mm × 70 mm, is placed on a rigid substrate that minimally absorbs impact energy It is situated beneath a hardened steel intermediate piece, shaped like a horizontal cylinder with a diameter of 25 mm and a length of 25 mm, featuring smoothly rounded edges with a radius of approximately 25 mm.
To test surface heaters, a cylinder with a diameter of 5 mm is laid horizontally on the sample, with the axis of a trace heater positioned across the sample For trace heaters with a non-circular cross-section, they must be aligned so that the impact is applied along the minor axis, ensuring the sample is flat against the steel plate.
In tests for electrical trace heaters designed for low-risk mechanical damage applications, a 1 kg hammer is permitted to drop from a height of 700 mm onto a horizontal cylinder, resulting in a nominal impact energy of 7 J.
Type tests – Additional tests for outdoor exposed surface heating
The rated output of the trace heater or surface heater shall be verified by the procedure described in 5.2.10.3.3
Determination of maximum sheath temperature
The maximum sheath temperatures of the trace heater or surface heater shall be verified by the procedure described in 5.2.13.2.4
A sample of at least 3 meters of trace heater or a representative surface heater, including all integral connections and end terminations, must be submerged in water at a temperature range of 10 ºC to 25 ºC for a duration of 2,000 hours (12 weeks).
After conditioning, the sample will undergo a dielectric test (5.2.1) and must endure this test for 1 minute without experiencing dielectric breakdown Subsequently, the same sample will be evaluated through the electrical insulation resistance test (5.2.2), with the measured resistance required to be no less than 50 MΩ.
A sample of trace heater approximately 300 mm long, or a representative sample of a surface heater, shall be exposed to a source of a xenon arc light as described in Procedure B of IEC 60068-2-5
The samples undergo 20 days of exposure to xenon arc radiation, with a cycle consisting of 20 hours of light followed by 4 hours of darkness After this exposure period, the samples are removed from the testing apparatus and evaluated using the cold bend test as outlined in section 5.2.7.
Trace heaters or surface heaters having a continuous metal sheath with no outer jacket shall be exempt from this test
A trace heater or surface heater sample, measuring at least 200 mm in length, must be tested by positioning it on a rigid flat steel support Above the sample, a metal cutting edge with a 0.25 mm radius should be mounted at a right angle An ohmmeter is then connected to the shorted conductors of the trace heater or surface heater and the metal cutting edge to conduct the test.
A proof load of 445 N will be gradually applied to the cutting edge as it contacts the sample An ohmmeter will be utilized to ensure that the cutting edge does not penetrate the insulation and make contact with the conductors of the trace heater or surface heater.
Six 1-meter samples of trace heaters will undergo testing to measure the electrical resistance of their metallic sheaths, braids, screens, or equivalent conductive coverings An ohmmeter with an accuracy of ± 1% will be used for these measurements, and the average initial resistance will be calculated from the results.
The samples will be positioned in the abrasion test apparatus, as illustrated in Figure 12 One end of each sample is secured to a horizontal reciprocating table, while the other end is connected to a 340 g mass Each sample is placed over a 90 mm radius cylinder at the table's end and covered with a fresh layer of grade 1/2 (medium) emery cloth or 120 grit silicon carbide/resin bond abrasive paper The cylinder's longitudinal axis is oriented horizontally and is perpendicular to each sample.
The table shall commence reciprocating at a rate of approximately 30 cycles per minute Each cycle shall consist of one complete back-and-forth motion with a stroke of approximately
The testing procedure involves stopping the table every 50 cycles to reposition or replace the abrasive material, ensuring that all samples are subjected to a fresh surface during subsequent cycles After completing 2,500 cycles, the resistance of the conductive braid or sheath of each sample is measured again, and the average resistance is calculated and compared to the initial average value It is crucial that the final average resistance does not exceed 125% of the initial average value, and if the samples are overjacketed, the underlying conductive braid or sheath must remain unexposed.
Reciprocating table with 160 mm stroke
Quarter cylinder with radius of 90 mm
Figure 12 – Abrasion test Tension test
A 30 kg mass, or a mass sufficient to impose the manufacturer's stated maximum tensile value, whichever is greater, shall be suspended from the free end of the heating section of a
A 1-meter long sample will be tested for 1 hour, ensuring that one end is securely fastened Throughout the test, there should be no breakage of the conductors or braid, and the insulation must remain visually undamaged, except in the areas where the sample is secured.
Rail system voltage spike test
Rail heating systems often experience voltage spikes from the power supply For outdoor metal structures, such as rail de-icing applications, trace heaters or surface heaters must undergo testing A sample of at least 2 meters of trace heater or a representative surface heater should endure 1,000 cycles of 5,000 V impulses, with each impulse having a rise time of 1.2 microseconds and a fall time of 50 microseconds Following this testing, the sample must meet the criteria outlined in sections 5.2.1 and 5.2.2.
Rail system over-voltage test
Some rail heating systems may face prolonged periods of increased voltage For outdoor metal structures, such as rail de-icing applications, a trace heater sample of at least 2 meters or a representative surface heater must be chosen This sample should be installed on a suitable mounting surface with expansion loops, if necessary, and any accessories should follow the manufacturer's installation guidelines Additionally, the ambient air temperature must be kept at the maximum specified for the system.
A voltage of 1,25 times the nominal operating voltage shall be applied for one hour The sample shall then pass the requirements of 5.2.1 and 5.2.2.
Type tests – Additional tests and test modifications for embedded heating
The rated output of the trace heater or surface heater shall be verified by the procedure described in 5.2.10.3.4
Determination of maximum sheath temperature
The maximum sheath temperatures of the trace heater or surface heater shall be verified by the procedure described in 5.2.13.2.5
The heater’s resistance to cutting shall be verified by the test described in 5.3.5
Trace heaters and surface heaters designed for embedded applications, like snow melting in concrete slabs, may be exempt from the flammability test outlined in section 5.2.3.
Type tests – Additional tests for applications of trace heating internal to
Type tests – Additional requirements for sprinkler systems
Normal and abnormal operation test
These tests are only applicable to trace heating systems intended for use on sprinkler systems
The trace heater and its components must comply with all relevant type tests outlined in section 5.2 Furthermore, they are required to successfully undergo both normal and abnormal operation tests to confirm their effectiveness Temperature control, as specified in section 4.4.1, is also a necessary inclusion.
Trace heating equipment must be installed on piping systems according to the manufacturer's guidelines It is essential to monitor temperatures to ensure that, when properly installed on a sprinkler system branch line and supply pipe configuration, the trace or surface heater maintains pipe surface temperatures between 4 °C and 38 °C.
The installation of trace heaters or surface heaters must follow the piping arrangements depicted in Figures 13, 14, and 15 Figure 14 presents an alternative to Figure 13, featuring a 2 m pipe with a 90 mm outside diameter and a single sprig, which should be oriented vertically down for tests at minimum ambient temperatures and vertically up for other tests Schedule 40 steel piping or equivalent must be used for these arrangements If non-metallic piping materials, such as plastic, are referenced by the manufacturer, testing must be conducted using the arrangements in Figures 13 or 14 for each material It is important to note that trace heating systems designed solely for sprinkler system mains and supply lines are only applicable to the arrangement shown in Figure 15.
The installation of the trace heating system, along with thermal insulation, must adhere to the manufacturer's guidelines, ensuring that the trace heating is positioned at the nearest allowable distance to the sprinklers as illustrated in Figure 13 (or Figure 14).
Thermocouples shall be installed to measure the pipe surface temperatures at locations as shown in Figures 13 (or Figure 14) and Figure 15
Each arrangement must be installed in a conditioning test chamber, with sprinkler outlets oriented vertically The test conditions require maintaining thermal equilibrium, indicated by constant temperature readings, achieved when three successive readings taken at intervals of 10% of the elapsed test duration (minimum 15 minutes) show no further increase The test chamber temperature should be set to the minimum ambient temperature specified in the manufacturer’s installation instructions, not exceeding -20 °C, with air movement limited to 2 m/s, or at an ambient temperature of 35 ± 2 °C, also with air movement not exceeding 2 m/s.
2 On 32 mm outside diameter sprig pipe adjacent to sprinkler head
3 On 90 mm outside diameter branch pipe approx 0,3 m from sprig
4 On 90 mm outside diameter branch pipe approx 0,9 m from sprig
Figure 13 – Sprinkler system temperature control test – branch line arrangement
2 On 32 mm outside diameter sprig pipe adjacent to sprinkler head
3 On 90 mm outside diameter branch pipe approx 0,3 m from sprig
4 On 90 mm outside diameter branch pipe approx 0,9 m from sprig
Figure 14 – Sprinkler system temperature control test – branch line – alternative arrangement
1 On 110 mm outside diameter pipe approximately 1 m from valve flange
2 On 110 mm outside diameter pipe approximately 0,5 m from valve flange
3 On body of OS&Y (outside screw and yoke) valve, away from heater sample
Figure 15 – Sprinkler system temperature control test – supply pipe arrangement
When installed as intended on a sprinkler system branch line as specified below, with the primary temperature controls disabled, pipe surface temperatures shall not exceed 55 °C, or
8 °C less than the minimum temperature rating of the sprinklers intended to be used with the system, whichever is less
NOTE This can be achieved by the use of a separate high-temperature limit controller to de-energize the trace heater with automatic reset and annunciation
The trace heating system including insulation shall be installed onto the sprinkler branch line as specified in Figure 13 (or Figure 14 with ‘sprig up’) For spiral wrapped trace heaters use
120 % of the trace heater length specified by the manufacturer for those spiralled sections
Thermocouples must be installed to measure pipe surface temperatures as indicated in Figures 13 and 14 The primary temperature control should be disabled, and the trace heating system should operate at 110% of its rated voltage The test setup is to be placed in a conditioning chamber with sprinkler outlets positioned vertically The test sample should be subjected to an ambient temperature of 35 ± 2 °C and exposed to air movement not exceeding 2 m/s.
Routine tests
The primary electrical insulation jacket of trace or surface heaters must endure a dry-spark test with a minimum voltage of 6,000 V a.c This test should utilize a sinusoidal waveform operating between 2,500 Hz and 3,500 Hz Specifically, for a 3,000 Hz supply, the product's speed in meters per second must not exceed 3.3 times the electrode length in centimeters, with this requirement being proportional to the frequency.
As an alternative to the dry-spark test, the dielectric tests in 5.2.1 shall be conducted (except that the test voltage is to be maintained for 1 s instead of 1 min)
After applying a metallic covering, braid, or equivalent conductive material, the heating device must undergo a dielectric test as specified in section 5.2.1, with the test voltage maintained for 1 second instead of 1 minute Additionally, non-metallic overjackets are required to pass a dry-spark test with a minimum voltage of 3,000 V a.c Alternatively, the dielectric tests outlined in section 5.2.1 can be performed, again with the test voltage held for 1 second.
The power output rating for each length of parallel trace heater must be verified for linearity through continuous or statistical testing methods For series resistance trace heaters or fixed resistive heaters, the power output rating is confirmed by measuring the d.c resistance, conductance, or current at a specified temperature Testing criteria should align with the output verification tests outlined in section 5.2.10, ensuring that the measured power output remains within the manufacturer's declared tolerances.
General
All the markings specified in IEC 60519-1 that are applicable to trace heating are included in the following requirements.
Product markings
Trace heaters, surface heaters and field-assembled components shall be clearly and permanently surface-marked in accordance with Table 2 or shall have a durable tag/label
For trace heaters or surface heaters that have factory-fabricated terminations, or for components with limited surface areas where clear printing is not feasible, the required markings must be placed on a durable tag or label This tag should be permanently affixed within 75 mm of the power connection fitting or gland, or the smallest unit container, rather than directly on the component itself.
ASSEMBLED COMPONENTS (except integral components) (1)
Manufacturer, trademark, or other recognized symbol of identification YES YES
Manufacturers' catalogue numbers, reference numbers, or models ensure that suitable applications—such as outdoor locations, wet environments, sprinkler systems, and internal tracing in potable water—are easily traceable to the corresponding product installation instructions and data sheets.
Month and year of manufacture, date coding, applicable serial number, or equivalent YES YES
The rated power output per unit length or surface area is defined at the specified rated voltage and a reference temperature, particularly for devices whose output varies with temperature This includes the resistance in ohms per unit length for series trace heaters, as well as the operating current or total wattage as relevant.
Trace heating equipment qualified for outdoor locations , wet locations, potable water and sprinkler systems is permitted to be so marked on the trace heating equipment YES YES
Applicable environmental requirements, such as IP (ingress protection) ratings, and area use requirements YES
(1) Other markings may apply for non-integral components
The manufacturer must provide specific installation instructions for trace heaters and surface heaters, clearly identifying applicable products and locations These instructions should include the intended uses, a list of compatible trace heaters or surface heaters, and essential safety statements such as the requirement for earth-fault protection and the necessity to de-energize power circuits before installation Additionally, it should emphasize keeping heater ends dry during installation and caution against using trace heaters in areas prone to mechanical damage For systems with mechanical protection, it must state that this protection should not be removed The instructions should also specify the need for proper grounding of the metal sheath and indicate the visibility of trace heating equipment through caution signs, especially in outdoor de-icing applications Furthermore, it is crucial that individuals involved in installation are adequately trained and that installations comply with local codes, particularly for sprinkler systems, which must be properly grounded and connected to a power supply The design and monitoring of these systems should adhere to relevant IEC standards, and any backup power provisions must also support the trace heating system.
[1] IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
[2] IEC/IEEE 60079-30-1 3 , Electrical apparatus for explosive atmospheres – Electrical resistance trace heating – Part 1: General and testing requirements
[3] NFPA 13, Standard for the installation of Sprinkler systems