6.3 Electrodes—For a given specimen configuration, it is possible that the dielectric breakdown voltage will vary considerably, depending upon the geometry and placement of the test electrodes. For this reason it is important that the electrodes to be used be described when specifying this test
method, and that they be described in the report.
6.3.1 One of the electrodes listed in Table 1 shall be specified by the document referring to this test method. If no electrodes have been specified, select an applicable one from Table 1, or use other electrodes mutually acceptable to the parties concerned when the standard electrodes cannot be used due to the nature or configuration of the material being tested. See references in Appendix X2 for examples of some special electrodes. In any event the electrodes must be described in the report.
6.3.2 The electrodes of Types 1 through 4 and Type 6 of Table 1 shall be in contact with the test specimen over the entire flat area of the electrodes.
6.3.3 The specimens tested using Type 7 electrodes shall be
of such size that all portions of the specimen will be within and no less than 15 mm from the edges of the electrodes during test. In most cases, tests using Type 7 electrodes are made with the plane of the electrode surfaces in a vertical position. Tests made with horizontal electrodes shall not be directly compared with tests made with vertical electrodes, particularly when the tests are made in a liquid surrounding medium.
6.3.6 Whenever the electrodes are dissimilar in size or shape, ensure that the one at which the lowest concentration of stress exists, usually the larger in size and with the largest radius, is at ground potential.
6.3.7 In some special cases liquid metal electrodes, foil electrodes, metal shot, water, or conductive coating electrodes are used. It must be recognized that it is possible that these will give results differing widely from those obtained with other types of electrodes.
6.3.8 Because of the effect of the electrodes on the test results, it is frequently possible to obtain additional information as to the dielectric properties of a material （or a group of materials） by running tests with more than one type of electrode. This technique is of particular value for research testing.