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  7. Abrupt Pull Test

What is the Abrupt Pull Test?
UL 817 is the U.S. standard for cord sets and power supply cords. NEMA plugs used in these cords are required to pass a strain relief test in UL 817 section 99, known as the abrupt pull test.

Who requires the test?
Underwriters Laboratories (UL). They are an independent product safety certification organization, headquartered in Northbrook, Illinois. UL generates standards and test procedures for products, materials, components, assemblies, tools and equipment, primarily focusing on product safety. For more information on Underwriters Laboratories, you can visit their website at:

What are the UL requirements?
UL requires the mechanical strength of the plug to be tested by repeatedly impacting the cord at the cord exit. This ensures that a pull force on the cord does not damage the internal plug terminations. During this test, the plug is mounted in a 45 degree steel plate. The plug blades and ground pin are anchored in the plate. A fixture with a rod, striker plate and a 1.1 kg (2.5 pound) weight are clamped to the cord. The weight is dropped 25 times. During and at the completion of this test, there is to be no loss of electrical continuity.

How does Interpower Corporation meet these requirements?
UL visits our production facilities 4 times each year. During each visit, they witness our testing a sample of 6 plugs. In addition, our Quality Assurance test lab conducts occasional testing to repeat this test as well throughout the year.You can view a video demonstration of an abrupt pull test, along with other testing videos on our Quality Topics webpage.If you have any questions about testing, or another topic you would like to see on our blog, please let us know by emailing