The Exchange Test Method

LABORATORY TEST METHOD NO. H-12: DIELECTRIC VOLTAGE BREAKDOWN

1. PURPOSE:

   To verify the integrity of electrical component insulation used in appliances through the application of a specific high voltage to the input power circuit over a period of time. In normal operation of the appliance, insulation breakdown (dielectric failure) could allow electrical current to pass directly to the user.

2. REFERENCE:

   Various UL Standards

3. TEST APPARATUS AND MATERIALS:

   3.1 Slaughter Model No.105-5 OW, Hi-pot tester or dielectric strength tester or similar equipment.

4. PROCEDURE:

   CAUTION : Because of the high voltage output, the dielectric strength tester can be very dangerous. Therefore, do not come in personal contact with the exposed test probe lead tips when testing. Do not leave the dielectric strength tester "ON" when not in actual use.
   • 4.1 Allow appliance to be tested to operate until the normal operating heat build-up has been attained. 
   • 4.2 Turn on the dielectric strength tester and set the voltage output to the specific amount required by the applicable UL Standard for the appliance being tested. 
   • 4.3 Touch one test probe to one prong of the bi-polar AC plug, then touch the other test probe to an exposed "DEAD" metal part, such as the outside case or chassis. Maintain this contact for 60 seconds. The buzzer and light of the dielectric tester will remain "OFF" if insulation of the appliance being tested does not breakdown. Repeat the same procedure using the other prong of the bi-polar AC plug.

5. REPORT:

   Report the result of this test in terms of whether the appliance being tested passed or failed applicable UL Standards. In case of failure, note the voltage at which the insulation breakdown occurred.