Publication Year Title EN/HD Year ANSI Z97.1 – American National Standard for Safety Glazing Materials Used in Buildings - Safety Performance Specifications and Methods of Test – –... PH
General
Photovoltaic modules can be utilized in various applications, making it essential to assess the potential hazards linked to each application and to design the modules accordingly.
Safety requirements and essential tests must be conducted to ensure compliance with the specific application class This section outlines the application classes and the construction qualities mandated for each class.
Application classes for PV-modules are defined as follows:
Class A: General access, hazardous voltage, hazardous power applications
Modules designed for this application class can be utilized in systems exceeding 120 V DC Those that have been certified for safety according to EN 61730-1 and the relevant section of EN 61730 are deemed to fulfill the safety class II requirements.
Class B: Restricted access, hazardous voltage, hazardous power
Modules designed for this application class are limited to systems that are safeguarded from public access through barriers and specific locations Those evaluated within this class offer protection through basic insulation and are deemed to fulfill the criteria for safety class 0.
Class C: Limited voltage, limited power applications
Modules rated for use in this application class are restricted to systems operating at less than
120 V DC Modules qualified for safety through EN 61730-1 and this part of EN 61730 within this application class are considered to meet the requirements for safety class III
NOTE Safety classes are defined within EN 61140
General
The lifespan and safety of photovoltaic (PV) modules can be affected by various hazards To address these risks, specific test procedures and criteria are outlined The tests a module undergoes will vary based on its intended application, with minimum testing requirements detailed in Clause 5.
NOTE Module safety tests are labelled MST
Tables 1 to 6 detail the origins of the necessary tests, with the third column providing additional information on the test origins, while the relevant test requirements are specified in the respective clauses.
The tests numbered 10 and 11, along with the remaining assessments, are derived from or closely resemble IEC 61215/IEC 61646, with pertinent references provided in the final two columns Additionally, certain tests based on IEC 61215/IEC 61646 have been adapted for EN 61730-2 and are detailed in the respective Clauses.
Preconditioning tests
MST 51 Thermal cycling (TC50 or TC200) 10.11 10.11
General inspection
Electrical shock hazard tests
These tests evaluate the potential risk to personnel from shock or injury due to contact with electrically energized components of a module, which may arise from design flaws, construction issues, or environmental and operational faults.
Table 3 – Electrical shock hazard tests
MST 11 Accessibility test ANSI/UL 1703
MST 12 Cut susceptibility test (not required for glass surfaces) ANSI/UL 1703
(not required unless metal framed)
MST 14 Impulse voltage test IEC 60664-1
MST 17 Wet leakage current test 10.15 10.20
MST 42 Robustness of terminations test 10.14 10.14
* The pass/fail criteria differ from those given in IEC 61215 and IEC 61646.
Fire hazard tests
These tests assess the potential fire hazard due to the operation of a module or failure of its components
MST 21 Temperature test ANSI/UL 1703
MST 23 Fire test ANSI/UL 790
MST 25 Bypass diode thermal test 10.18
MST 26 Reverse current overload test ANSI/UL 1703
Mechanical stress tests
These tests are to minimise potential injury due to mechanical failure.
MST 32 Module breakage test ANSI Z97.1
Component tests
MST 15 Partial discharge test IEC 60664-1
MST 33 Conduit bending ANSI/UL 514C
MST 44 Terminal box knock out test ANSI/UL 514C
5 Application classes and their necessary test procedures
The tests a module undergoes are determined by its application class as outlined in EN 61730-1, detailed in Table 7 The sequence of these tests is specified in Figure 1.
Some tests shall be carried out as preconditioning tests.
This test sequence allows for the simultaneous execution of }EN 61730-2~ alongside IEC 61215 or IEC 61646 Consequently, the environmental stress tests outlined in IEC 61215 or IEC 61646 can effectively function as preconditioning tests for }EN 61730-2~.
Table 7 – Required tests, depending on the application class
MST 51 Thermal cycling (T50 or T200) MST 52 Humidity freeze (10HF) MST 53 Damp heat (DH1000) MST 54 UV pre-conditioning
MST 11 Accessibility test MST 12 Cut susceptibility test MST 13 Ground continuity test MST 14 Impulse voltage test MST 16 Dielectric withstand test MST 17 Wet leakage current test
X X X MST 42 Robustness of terminations test
MST 21 Temperature test MST 22 Hot spot test Fire test
MST 26 Reverse current overload test
MST 32 Module breakage test MST 34 Mechanical load test
MST 15 Partial discharge test MST 33 Conduit bending MST 44 Terminal box knockout test
- Test needs not be carried out.
* Different test levels for application classes A and B
** A European fire test is under consideration
For safety testing, six modules and one laminate module (without a frame) will be randomly selected from a production batch, following the IEC 60410 procedure These modules must be made from specified materials and components, adhering to relevant drawings and process sheets, and must have passed the manufacturer's standard inspection and quality control procedures Each module should be fully complete and include the manufacturer's instructions for handling, mounting, and connection, along with the maximum permissible system voltage.
When the modules to be tested are prototypes of a new design and not from production, this fact shall be noted in the test report (see Clause 7)
The test report will be prepared in accordance with ISO/IEC 17025, including all necessary information for interpretation as requested by the client Key elements of the report will consist of: a title; the name and address of the test laboratory; unique identification for the report; client details; a description of the tested item; its characterization and condition; dates of receipt and testing; identification of the test method; references to sampling procedures; any deviations or additional information relevant to the tests; measurements and results supported by visual aids; a statement on the type of impulse voltage test conducted; estimated uncertainty of results; signatures of responsible personnel; a disclaimer that results pertain only to tested items; and a note that reproduction of the report requires written approval from the laboratory.
A copy of this report shall be kept by the manufacturer for reference purposes.
1 If the module is only used with frame and the frame is an essential part to fulfil the isolation requirement, the laminate can be replaced by a module
The modules will be organized into groups and undergo the safety tests outlined in Figure 1, following the specified sequence Selection of the modules will ensure compliance with the preconditioning tests detailed in section 4.2 Each box in Figure 1 corresponds to the relevant subclause in this section.
NOTE Spare modules may be included in the safety test program provided that they have been appropriately environmentally tested to meet the necessary prerequisites
Test procedures and criteria, including necessary initial and final measurements, are outlined in Clauses 10 and 11 Certain tests, which are similar to those in IEC 61215/IEC 61646, are specified in Clause 4 It is essential for testers to adhere closely to the manufacturer's instructions regarding handling, mounting, and connections during these tests.
Wet leakage current MST 17 test
Robustness of terminations test MST 42
Terminal box knock out test MST 44 MST 44
Conduit bending MST 33 test MST 33
Number of modules depends on the module size
UV pre-conditioning test MST 54
Bypass diode thermal test MST 25 16
01 17 The numbers in each box are references to final measurements, that are to be performed after MST or MPT (if required) In this example:
Wet leakage current MST 17 test
Edition 1 are near the red bar
The module product under evaluation shall be judged to have passed the safety qualification test, if the test samples meet all of the criteria of each individual test
If any module does not meet these test criteria, the module product under evaluation shall be deemed not to have met the safety test requirements
NOTE The nature of the failure will determine the extent of re-testing requirements
Visual inspection MST 01
To detect any visual defects in the module
This test is identical with 10.1 from IEC 61215/IEC 61646 with the additional inspection criteria of
– any other conditions which may affect safety;
– markings not consistent with Clause 11 of EN 61730-1
Document and photograph any cracks, bubbles, or delaminations, as these issues may worsen and compromise module safety in future tests Minor visual conditions not classified as major defects are acceptable for safety test approval.
For safety test approval, major visual defects include: a) broken, cracked, or torn external surfaces; b) bent or misaligned external surfaces, such as superstrates, substrates, frames, and junction boxes that compromise module safety; c) bubbles or delaminations creating a continuous path between any part of the electrical circuit and the module's edge, or showing significant growth during testing; d) signs of molten or burned encapsulant, back sheet, diode, or active PV components; e) loss of mechanical integrity that jeopardizes the safety of the module's installation and operation; and f) markings that do not comply with Clause 12 of EN 61730-1.
Accessibility test MST 11
To determine if uninsulated electrical connections represent a shock hazard to personnel
The apparatus is as follows: a) A cylindrical test fixture Type 11 according to Figure 7 of IEC 61032 b) An ohmmeter or continuity tester
To test the module, first, mount and wire it according to the manufacturer's instructions Next, connect an ohmmeter or continuity tester to the module's electric circuit and the test fixture Remove any covers, plugs, and connections from the module that can be taken off without tools Then, probe around all electrical connectors, plugs, junction boxes, and other accessible areas of the module's circuitry with the test fixture Finally, monitor the ohmmeter or continuity tester to check for electrical contact with the module's circuitry during the probing process.
At no time during the test shall there be less than 1 MΩ resistance between the test fixture and the module electric circuit.
During the test, it is crucial that the probe does not come into contact with any live electrical components This test is conducted both at the start and conclusion of the sequence, as illustrated in Figure 1 Additionally, it can be performed at any point in the test sequence if there is a concern that active electrical circuitry may have been exposed during previous tests.
Cut susceptibility test MST 12
The objective is to assess the durability of the front and rear surfaces of polymeric material modules during installation and maintenance, ensuring they can endure routine handling while safeguarding personnel from the risk of electric shock.
The test fixture illustrated in Figure 2 is engineered to move a carbon steel blade, measuring 0.64 mm ± 0.05 mm in thickness (such as the back of a hacksaw blade), across the module's surface while applying a force of 8.9 N ± 0.5 N.
To conduct the procedure, first, position the module horizontally with the front surface facing upward Next, place the test fixture on the surface for one minute before moving it across the module at a speed of (150 ± 30) mm/s.
Repeat the procedure five times in different directions c) Repeat a) and b) for the rear surface of the module
Repeat MST 01, , MST 16 and MST 17
The pass criteria are as follows: a) No visual evidence that the superstrate or substrate surfaces have been cut, exposing the active circuitry of the module b) measurements
!Text deleted" MST 16, MST 17 shall meet the same requirements as for the initial
Test point carbon steel strip (i.e hacksaw blade)
A 150 mm from axis to center of weight
B 170 mm from axis to test point
C Test point – 0,64 mm thick steel strip
Q Total force exerted at test point Q: 8,9 N
Ground continuity test MST 13
To ensure proper grounding in a photovoltaic (PV) system, it is essential to verify the conductive path between all exposed conductive surfaces of the module This test is necessary only when the module includes exposed conductive components, such as a metal frame or a metallic junction box.
The setup includes a constant current supply that generates a current 2.5 times greater than the maximum over-current protection rating of the module being tested, as specified in MST 26, along with an appropriate voltmeter for measurement.
NOTE 1 According to EN 61730-1 the maximum over-current protection rating has to be provided by the manufacturer
The maximum over-current protection rating of a module is equivalent to its series fuse rating, which may be necessary for the installation of photovoltaic (PV) arrays As specified in Subclause 12.2 of EN 61730-1, this rating must be supplied by the manufacturer.
NOTE 3 A procedure for determination of maximum reverse current is described in EN 50380
To conduct the grounding test, first, select the manufacturer's designated grounding point and connect it to one terminal of the constant current supply Next, identify an adjacent exposed conductive component that is physically distant from the grounding point and connect it to the other terminal Attach a voltmeter to the two components near the current leads Apply a current of 2.5 times ± 10% of the module's maximum over-current protection rating for at least 2 minutes, then measure the applied current and the resulting voltage drop Afterward, reduce the current to zero and repeat the test on an additional frame component.
The resistance between the selected exposed conductive component and each other conductive component of the module shall be less than 0,1Ω.
Impulse voltage test MST 14
The article assesses the solid insulation's ability to endure atmospheric over-voltages and those caused by the switching of low-voltage equipment.
NOTE If the PV module is not going to be sold without frame, the impulse voltage test should be done with the module framed.
The apparatus is as follows: a) Impulse voltage generator b) Oscilloscope
To conduct the procedure, first, cover the entire module with copper foil and connect it to the negative terminal of the impulse voltage generator Next, link the shorted output terminals of the module to the positive terminal of the generator.
1) Thickness copper 0,03 mm to 0,05 mm
3) Total thickness 0,05 mm to 0,07 mm c)
According to IEC 60664-1, specifically section 2.2.2.1.1, modules are classified under over-voltage category III The testing level has been lowered by one step due to the presence of over-voltage protection devices in typical systems Conversely, to ensure reinforced insulation for application class A and safety class II, the testing level for application class A has been elevated by one step.
Table 8 – Impulse voltage versus maximum system voltage
Impulse voltage Maximum system voltage
Linear interpolation is permitted for intermediate values of maximum system voltage Three consecutive pulses must be applied, followed by a change in the polarity of the pulse generator terminals, after which three additional successive pulses should be applied.
In the absence of illumination, apply the surge impulse voltage specified in Table 8 using the waveform illustrated in Figure 3 from the impulse voltage generator The oscilloscope will be used to observe the pulse waveform, ensuring that the rise time and pulse duration are verified for each test conducted.
!Conducting glue (resistance < 1 Ω, measuring area: 625 mm )."
To ensure test reproducibility, the test is carried out at room temperature and relative humidity below 75% The impulse test is conducted in accordance with IEC 60060-1, following a specific procedure.
The pass criteria stipulate that there must be no signs of dielectric breakdown or surface tracking on the module during testing, and there should be no significant visual defects as outlined in section 10.1.
The parameter 0 1 represents the starting point of the impulse voltage, which is identified as the intersection of the time axis and the line connecting points A and B on a linear time scale diagram.
Figure 3 – Wave-form of the impulse voltage according to IEC 60060-1
Dielectric withstand test MST 16
To determine whether or not the module is sufficiently well insulated between current carrying parts and the frame or the outside world
The test shall be made on modules at ambient temperature of the surrounding atmosphere (see IEC 60068-1) and in a relative humidity not exceeding 75 %
This test is identical with test 10.3 from IEC 61215/IEC 61646 with test levels depending on the application class and the maximum system voltage.
The maximum test voltage for application-class A is set at 2,000 V plus four times the maximum system voltage, while for application-class B, it is defined as 1,000 V plus two times the maximum system voltage.
Temperature test MST 21
This temperature test aims to identify the maximum reference temperatures for different components and materials utilized in module construction, ensuring their suitability for use.
The ambient temperature during the test may be in the range of 20 °C to 55 °C
The test requires that the irradiance be at least 700 W/m², measured coplanar with the module using a calibrated device with an accuracy of ±5%, following IEC 60904-2 and IEC 60904-6 standards Additionally, all measurements must be conducted at wind speeds below 1 m/s.
The module being tested must be placed on a platform made of wood, pressed wood, or plywood, with a thickness of about 19 mm The side of the platform facing the test sample should be painted flat black, and it must extend at least 60 cm beyond the module on all sides.
The test module must be installed on the platform following the manufacturer's guidelines In cases where multiple installation options are available, the option that presents the worst-case scenario should be selected If no specific instructions are given, the module should be mounted directly onto the platform.
The module component temperatures shall be measured by a calibrated device or system, with an maximum uncertainty of ±2 °C
The module will be tested under both open- and short-circuit conditions, with stabilized temperature data collected for each scenario Thermal stability is achieved when three consecutive readings, taken five minutes apart, show a temperature variation of less than ±1 °C.
The measured component temperatures (T obs) will be normalized by adjusting for the difference between the 40 °C reference ambient and the actual measured ambient temperature (T amb) This is achieved using the equation T con = T obs + (40 – T amb), where T con represents the normalized temperature.
If unacceptable performance is observed during a temperature test, and this performance is linked to a test condition that, while within specified limits, is deemed excessively severe—such as an ambient temperature near the allowable limits—the test may be repeated under conditions that are more representative of normal circumstances.
When the irradiance deviates from 1,000 W/m², it is essential to measure temperatures at two additional irradiance levels that are at least 80 W/m² apart A quadratic extrapolation is then performed to estimate the temperature corresponding to an irradiance of 1,000 W/m².
Module superstrate above the centre cell
Module substrate below the centre cell
Terminal enclosure interior air space
Insulation of the field wiring leads
External connector bodies (if so equipped).
Diode bodies (if so equipped).
NOTE Due to the many possible variations in construction, more than one data gathering point for each cited location may be used, at the discretion of the test laboratory
The module must meet specific requirements, ensuring that no measured temperatures surpass the limits outlined in Table 9 Additionally, there should be no signs of creeping, distortion, sagging, charring, or any similar damage to any component of the module, as specified in section 10.1.
Part, material or component Temperature limits °C Insulating materials: c)
Field wiring terminals, metal parts 30 above ambient
Field wiring compartments that wires may contact d) a) or d) , whichever is greater, or b)
The mounting surface and adjacent structural members must adhere to specific temperature guidelines The material's relative thermal index (RTI) should be less than 20 °C If a marking indicates the minimum temperature rating for conductors, terminals within a wiring compartment may exceed this rating but must not exceed 90 °C Higher temperatures are permissible if it is confirmed that they do not pose a fire or electric shock risk Additionally, temperatures on insulated conductors must not surpass their rated temperature.
Fire test MST 23
PV modules installed as roofing materials or mounted above existing classified roofing must meet the single burning brand and spread of flame tests specified in Annex A, following ANSI/UL 790 standards Adequate samples must be supplied to form a single test assembly for both the spread of flame and single burning brand tests.
Products meeting these standards are designed to be non-flammable, provide significant fire protection for the roof deck, remain securely in place, and are unlikely to generate flying embers.
The PV module system must achieve a fire resistance classification in accordance with Annex A requirements For modules installed over existing roof coverings, compliance with the single burning brand and spread of flame test is mandatory Furthermore, additional sequential testing as specified in ANSI/UL 790 is necessary for modules that serve as roof covering materials.
IEC Technical Committee 82 aims to adopt international standards like ISO 834 for fire resistance testing of PV modules In the interim, the outlined tests will serve as the minimum safety qualification requirements.
Reverse current overload Test MST 26
Modules consist of electrically conductive materials housed within an insulating system During reverse current fault conditions, the module's tabbing and cells must dissipate energy as heat before the circuit is interrupted by an over-current protector This test aims to assess the risk of ignition or fire resulting from such conditions.
The module under test is to be placed with its superstrate face down onto a 19 mm thick
The back surface of the module must be covered with a single layer of untreated cotton cheesecloth, which has a weight of 26 m²/kg to 28 m²/kg and a thread count of 32 by 28.
Any blocking diode provided shall be defeated (short-circuited)
The test shall be conducted in an area free of drafts
The irradiance on the cell area of the module shall be less than 50 W/m 2
To conduct reverse testing on the module, connect a laboratory DC power supply with the positive output linked to the module's positive terminal The reverse test current (\$I_{test}\$) must be set to 135% of the module's overcurrent protection rating as specified by the manufacturer Ensure that the test supply current does not exceed \$I_{test}\$, and gradually increase the test supply voltage to initiate reverse current flow through the module.
! " soft pine board, covered by a single layer of white tissue paper
The test shall be continued for 2 h, or until ultimate results are known, whichever occurs first
NOTE 1 Concerning the maximum overcurrent protection rating, see 12.2 of EN 61730-1
The maximum over-current protection rating of a module is equivalent to its series fuse rating, which may be necessary in the design of photovoltaic (PV) arrays As specified in Subclause 12.2 of EN 61730-1, this maximum rating must be supplied by the manufacturer.
The pass criteria stipulate that there must be no flaming of the module, nor any flaming or charring of the cheesecloth and tissue paper in contact with it Additionally, MST 17 must adhere to the same requirements as those established for the initial measurements.
Module breakage test MST 32
The purpose of this test is provide confidence that cutting or piercing injuries can be minimized if the module is broken.
NOTE If the glass is qualified in accordance with EN 12150-1 this test can be omitted
The test described herein is derived from ANSI Z97.1, Impact test
The apparatus consists of leather punching bags that are uniform in shape and size These bags must be filled to the specified weight with chilled lead shot or pellets, ranging from 2.5 mm to 3.0 mm in diameter.
The impactor bag design, as illustrated in Figure 4, requires the exterior to be wrapped in 1.3 cm wide glass filament reinforced pressure-sensitive tape for testing To ensure stability during testing, a test frame similar to those depicted in Figures 5 and 6 must be constructed from steel channel (approximately C100 mm × 200 mm or larger) with a minimum moment of inertia of about 187 cm\(^4\) The frame should be securely welded or bolted at the corners and anchored to the floor to prevent movement and twisting during impact When filled with lead shot, the impactor bag will weigh approximately 45.5 kg and is capable of delivering 542 J of kinetic energy from a vertical drop of 1.2 m.
Ensure the module sample is securely mounted and centered on the test frame according to the manufacturer's instructions The initial setup should maintain a distance of no more than 13 mm from the surface of the module sample.
To test the durability of the module sample, position the impactor 50 mm from its center Lift the impactor to a height of 300 mm, stabilize it, and release it to strike the sample If the sample remains intact, repeat the process from a height of 450 mm, and if there is still no breakage, continue testing from a height of 1,220 mm.
The module passes the breakage test if it meets any of the following criteria: a) no openings large enough for a 76 mm (3-inch) diameter sphere to pass through develop upon breakage; b) the ten largest crack-free particles, measured 5 minutes after the test, weigh no more than 16 times the sample's thickness in millimeters; c) no particles larger than 6.5 cm² are ejected during breakage; or d) the sample remains intact without breaking.
Rod may be bent as shown or eye nut may be threated onto rod
(install before bag is taped)
Fill bag with lead shot so that total weight of assembly is 45 500 g ± 500 g
Tape bag with 13 mm wide tape
Use 3 rolls (165 m) and tape in diagonal, overlapping manner.
Cover entire surface of bag
25 mm long x 32 mm diameter (series of metal washers may be used)
8,0 mm or 10 mm threaded metal rod
5 mm ± 1,5 mm thick Eye nut for lifting bridle (see Figure 6)
Concrete wall, steel beam, or other sturdy construction
Alternate means of bracing frame, use one brace at each vertical member
Bridle for lifting impactor, use stranded steel cable approximately
Maximum 13 mm when impactor is hanging free
Width of test specimen minus 20 mm 1 525 mm min.
2 480 mm m in 2 065 mm He ig ht o f te st sp ec im en m in us 25 mm
This portion or frame not required if swivel attachment is mounted on separate construction
Swivel attachment-locate at vertical centerline of test specimen and a minimum of 1 525 mm above horizontal centerline
Su bfr am e me mb er s fo r te st s pec im en sm al le r th an 8 65 mm × 1 939 m m
NOTE Clamping frame for holding test specimen not shown
Partial discharge-test MST 15
The test refers to 4.1.2.4 of IEC 60664-1
Polymeric materials designated as superstrates or substrates must undergo the partial discharge test if they lack appropriate IEC insulation pre-qualification This requirement applies to all polymeric materials used in these roles.
NOTE In order to achieve a certain statistical relevance 10 pieces should undergo the test The size of the specimen depends on requirement originating from the test apparatus
Calibrated charge measuring device or radio interference meter according to IEC 60664-1 The geometry of the electrodes shall be in conformance with EN 60243-1.
The procedure outlined in IEC 60664-1, specifically in sections C.2.1 and D.1, requires that the test voltage be increased by 10% starting from a value below the maximum system voltage until reaching the inception voltage, where partial discharge occurs.
When conducting tests, it is essential to begin at zero voltage, as the maximum system voltage may be unspecified or unknown Any voltage below the maximum system voltage can be utilized for testing purposes.
When the test voltage is increased, partial discharges may occur intermittently The inception voltage is defined as the test voltage at which continuous discharges last for a minimum of 60 seconds Subsequently, the voltage should be reduced to the level where the partial discharge extinction voltage is attained.
Partial discharges may intermittently vanish, so it is essential that they remain below 1 pC for at least 60 seconds at extinction voltage The extinction voltage is deemed achieved when the charge intensity decreases to 1 pC, and this measurement must be taken with an accuracy greater than the specified threshold.
5 % d) The partial discharge extinction voltage may be influenced by environmental conditions These influences are taken into account by a basic safety factor F 1 of 1,2. e) f) Repeat the measurement with 10 test samples.
It is advisable to perform the partial discharge-test before using the polymeric material in the PV module construction
According to section 4.1.2.4 of IEC 60664-1, the hysteresis factor is set to 1, while an additional safety factor of F3 = 1.25 is mandated for safety class A Consequently, the initial test voltage is established at 1.5 V OC, as specified by the module manufacturer.
The solid insulation is deemed acceptable if the mean value of the partial discharge extinction voltage, when reduced by the standard deviation, exceeds 1.5 times the specified maximum system voltage.
Conduit bending test MST 33
Modules equipped with junction boxes for permanent wiring systems using conduit must ensure that the box construction can endure the load forces applied to the conduit both during and after installation.
Two 460-mm lengths of the correct trade size conduit, along with suitable fittings, must be installed on opposite sides of the box For boxes designed for non-metallic conduit, the test lengths should be welded to the fittings and allowed to cure for at least 24 hours before assembly.
The test assembly, featuring a centrally located box, should be positioned on supports as shown in Figure 7 The supports must be spaced 760 mm apart, in addition to the distance between the conduit ends within the box, to ensure the necessary bending moment is applied to the sample being tested.
The load indicated in Table 10 for the conduit size must be suspended from the center of the box for 60 seconds During this period, the box and the conduit lengths should be rotated through a full revolution around the major axis of the assembly.
The attachment walls of the module junction box shall not rupture or separate from the conduit
NOTE If breakage of the conduit occurs prior to damage to the box or separation of the joint, performance of the box is considered acceptable.
Trade size of conduit mm Force load
Terminal box knockout tests MST 44
Removable hole covers, known as knockouts, in module terminal enclosures must securely stay in place under normal force while allowing for easy removal when installing permanent wiring system components in the field.
A sample of the polymeric terminal box with knockouts will be tested in an “as-received“ condition at a 25 °C ambient temperature.
Another sample of the polymeric box is to be conditioned for 5 h in air maintained at –20 °C ±1 °C The test shall be repeated on the box immediately following this conditioning
The knockout shall be easily removed without leaving any sharp edges or causing any damage to the box The procedure is as follows:
To initiate the process, apply a force of 44.5 N to the knockout for 1 minute using a mandrel that is at least 38 mm long and 6.4 mm in diameter, featuring a flat end Ensure the force is directed perpendicularly to the knockout plane at the optimal point for movement After waiting for 1 hour, measure the displacement between the knockouts and the box.
Step 2 – The knockout shall then be removed by means of a screwdriver, used as a chisel.
The edge of a screwdriver blade may be run along the inside edge of the resulting opening once only, to remove any fragile tabs remaining along the edge.
Step 3 – Repeat steps 1 and 2 on two additional knockouts
For a box employing multi-stage knockouts, there shall be no displacement of a larger stage when a smaller stage is removed
The knockout must stay securely in position after a steady force is applied, ensuring that the gap between the knockout and the opening does not exceed 0.75 mm when measured.
The knockout shall be easily removed without leaving any sharp edges or causing any damage to the box
IEC 60068-2-21:1999, Environmental testing – Part 2-21: Tests – Test U: Robustness of terminations and integral mounting devices
NOTE Harmonized as EN 60068-2-21:1999 (not modified).
IEC 60364-1:2001, Electrical installations of buildings − Part 1: Fundamental principles, assess- ment of general characteristics, definitions
NOTE Superseded by IEC 60364-1:2005, which is at draft stage for harmonization as HD 60364-1 (modified)
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
NOTE Harmonized as EN 60529:1991 (not modified)
IEC 61345:1998, UV test for photovoltaic (PV) modules
NOTE Harmonized as EN 61345:1998 (not modified)
IEC 61721:1995, Susceptibility of a photovoltaic (PV) module to accidental impact damage (resistance to impact test)