During the certification process, the capacitors are subjected to ten impulses of alternating polarity. After that an endurance test is performed. This test is to confirm that the capacitors can withstand multiple impulses and still perform reliably under AC voltage conditions. The endurance test is an AC life test at 425VAC/60Hz with an hourly a 1000VAC impulse applied for 0.1 seconds. The length of this test is 1000 hours.