ASTM D257 : 99

1.1 These test methods cover direct-current procedures for the determination of dc insulation resistance, volume resistance, volume resistivity, surface resistance, and surface resistivity of electrical insulating materials, or the corresponding conductances and conductivities.

1.2 These test methods are not suitable for use in measuring the electrical resistivity/conductivity of moderately conductive materials. Use Test Method D4496 to evaluate such materials.

1.3 The test methods and procedures appear in the following sections:

Test Method or Procedure Section Calculation 13 Choice of Apparatus and Test Method 7 Cleaning Solid Specimens 10.1 Conditioning of Specimens 11 Effective Area of Guarded Electrode X2 Electrode Systems 6 Factors Affecting Insulation Resistance or Conductance X1 Measurements Humidity Control 11.2 Liquid Specimens and Cells 9.4 Precision and Bias 15 Procedure for the Measurement of Resistance or Conductance 12 Referenced Documents 2 Report 14 Sampling 8 Significance and Use 5 Specimen Mounting 10 Summary of Test Methods 4 Terminology 3 Test Specimens for Insulation, Volume, and Surface 9 Resistance or Conductance Determination Typical Measurement Methods X3

1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Note 1.