IEC 60335-1 is a general specification that governs the safety of household appliances. Within the specification, glow wire testing is used to evaluate flammability of non-metallic materials supporting current carrying connections used within the appliance. The glow wire test severity prescribed in IEC 60335-1 is determined by whether the appliance is attended or unattended during use, and by the amount of current that is carried by the connection. Attended appliances are basically any appliance that is operated by an attending consumer such as vacuum cleaners, irons, and coffee pots. Unattended appliances are those that are set in place and operated on their own. Such examples include refrigerators, cooking units, dishwashers, washing machines, and dryers.
Connectors used in an application that is categorized as unattended with current greater than 0.2A are subject to the most severe evaluation. To comply with this specification, three levels of flammability evaluation may be required:
1. In order to pass the first level of evaluation, the material must have a minimum GWFI 850 ºC OR the end product must pass the glow wire test at 850 ºC. It is important to note that for the end product to pass, the sample must self-extinguish within 30 seconds as identified in the above passage. The test is subject to the procedure 60695-2-11.
2.In order to pass the second level of evaluation, the material must have a minimum of GWIT 775 ºC OR the end product must pass the glow wire test at 750 ºC. It is important to note that if the end product is tested, any ignition must self-extinguish within 2 seconds or the surrounding components must pass a third level of evaluation.
3.The third level of evaluation (performed only if the connector exhibits a flame for longer than 2 seconds) is not performed directly on the connector, but instead is performed on any components within the appliance falling within a theoretical envelope above the connector. Components within the envelope made from a material that has a minimum flammability designation as UL 94 V1 are not subject to further evaluation. However, components within the envelope that have less than UL 94 V1 are subject to a needle flame test.
Refer to the flow diagram located in the Appendix A for an illustration of the testing required for materials supporting connections carrying current greater than 0.2 A in unattended appliances.
Connectors used in Appliances that are categorized as unattended with a current less than 0.2A or categorized as attended appliances are subjected to less severe testing methods. It is important for the appliance manufacturer to understand the appropriate categorization of their finished product, so as to apply the correct level of testing per IEC 60335-1 to the components.
Conclusion:
TE Connectivity is committed toward providing a range of products to help Appliance customers meet the flammability requirements of IEC 60335-1. TE is continuously evaluating new resins to determine if these materials are suitable for applications where Glow Wire compliance is needed.
Our experience has shown that simply using a resin material that meets the minimum Glow Wire Flammability Index (GWFI) and the Glow Wire Ignition Temperature (GWIT) values for a connector housing will not necessarily produce a final part that will pass the Glow Wire Test (GWT) at 750 ºC without flames (≤ 2 seconds). It is important to keep in mind that GWFI and GWIT values are derived from testing performed on test plates, while the GWT is performed on end products. Often times this means the end product will see contact with the heated element for the duration of the test, while the test plates will only see limited contact due to the element burning through the thickness of the plate soon after initial contact. At TE, we work to eliminate any doubt regarding the performance of our products in glow wire tests. Because of this, TE only declares a product to be “Glow Wire Compliant” when the end products have satisfactorily passed TE testing to the most stringent current Glow Wire requirements in IEC 60335-1. Please look to TE Connectivity to answer any questions regarding its commitment to offering the best solutions for your needs.
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