15.2 Entry of water (rainwater, seawater, etc.) into outdoor equipment
[Basic requirements]
Equipment installed outdoors shall be constructed in such a way to avoid water from coming into contact with any live parts etc., in order to prevent smoke emission, ignition, fire and electric shock hazards. Furthermore, the insulating parts adjacent to conductive parts to which hazardous voltages are applied shall have sufficient tracking resistance characteristics, in order to prevent smoke emission, ignition, and fire hazards.
[Design standards]
1) Equipment shall be constructed in such a way to prevent water gaining entry through the openings or gaps in the equipment from coming into contact with any live parts or any current-carrying parts which may give rise to hazardous malfunctions.
2) Equipment shall be constructed in such a way to prevent the drainage openings in the equipment from being blocked by foreign matter such as sand, dust, dirt and the remains of dead insects, leading to the collection of water and resulting in hazards such as the emission of smoke, ignition, fire and electric shock.
3) The insulating parts adjacent to conductive parts to which hazardous voltages are applied shall have sufficient tracking resistance characteristics. The following structures can be regarded as having sufficient tracking resistance characteristics.
a) The insulating parts on PWB units that are fully sealed with resin that has sufficient tracking resistance.
b) The insulating parts on PWB units that are partially sealed with resin that has sufficient tracking resistance.
Note: If the partial potting complies with ANNEX 3 (Definition of the term "covered by materials"), then it can be regarded as having sufficient tracking resistance characteristics.
c) The insulating parts such as contact components (switches, relays and thermostats), coil parts (feed valves) and PWBs that have sufficient tracking resistance characteristics.
[Criteria]
1) Compliance is determined by conducting the following water spray test:
a) Check for the adhesion of water by spraying water according to the water spray test specified in IEC 60529: 2001 (JIS-C-0920: 2003) "Degrees of protection provided by enclosures (IP Code)." (IPX4 or above is recommended.)
Measure the insulation resistance of the equipment, two minutes after water spraying.
b) No water shall come into contact with any live parts or any current-carrying parts which may give rise to hazardous malfunctions. Furthermore, the insulation resistance of the equipment
shall be 1 M or more, two minutes after the test is completed.
2) Compliance is determined by conducting tests appropriate to the actual use of the equipment.
3) Compliance is determined by conducting the following tracking resistance test.
Criterion: No ignition shall occur up to 200 drops.
Test sample: The insulating parts adjacent to conductive parts to which hazardous voltages are applied in actual equipment under actual operating conditions
Test liquid: An aqueous solution (whose water is either distilled water or ion-exchanged water) of ammonium chloride with a 0.2% concentration (NH4Cl which meets the standard for reagent class 1)
Voltage: The rated voltage
If scintillation exceeds the drip interval, the dripping shall be temporarily suspended until the scintillation subsides, after which the dripping shall be resumed.
Note1: If non-resetting protective devices in actual equipment operate before igniting, then the test can be regarded as being conformant and the test can therefore be concluded.
However, if protective devices that are not of the non-resetting type operate, then the test shall be resumed and continued until 200 drops are applied after the protective devices are reset.
Note2: If it is impossible to apply the drops to the target insulating parts adjacent to conductive parts in actual equipment, then the test shall be conducted by taking out the parts. In this case, test liquid may be dripped onto the insulating parts in the same position as actual equipment.
Note3: Whenever the test liquid is dripped, currents must flow between conductive parts through an aqueous solution of ammonium chloride, unless currents cannot physically flow between conductive parts through an aqueous solution of ammonium chloride because distances through the insulation between conductive parts is too long or there is a partition between conductive parts.
Note4: In the case of the conductive parts on a PWB, only the conductive part under the worst conditions among them may be tested. The following are cases where conductive parts are under the worst condition.
a) Conductive parts most unfavorable in the relationship between the voltage and insulation distance
b) Conductive parts presumed to accumulate a lot of dust, such as near the fresh-air intake of a cooling fan
3-a) Compliance is determined on the basis of Level I in PCSS-Q-07003 "Moisture resistance test of fully resin-sealed PWB unit."
3-b) Compliance is determined by conducting tests appropriate to the actual use of the equipment (Composite Temperature/Humidity Cyclic Test).
3-c) Compliance is determined on the basis of PCSS-Q-08002 "Resistance to tracking of live parts."