In general test results and the performance of electrical apparatus are significantly influenced by variations in such parameters as temperature, barometric pressure, and humidity. A meaningful comparison of the results of two tests made under different ambient conditions is possible when the result of one of the tests is corrected or adjusted to indicate the results that would have been obtained if the ambient conditions for that test had been identical with those for the other. Especially in the situation where several tests performed under different conditions are to be compared, it is advantageous to select standard reference values for all pertinent parameters and then to correct or adjust the results of each test to indicate the results that would have been obtained if all tests had been performed under identical conditions, that is, under the reference ambient conditions. It is the purpose of this document to identify and recommended a set of standard reference values for certain ambient parameters which are significant in electrical test measurements. Even though agreed-upon correction factors may not be available, the ambient temperature, the barometric pressure, and the relative humidity should always be recorded and reported. In this way retesting will not be necessary when agreed-upon correction factors become available.