Abstract: In this paper, influencing factors and equivalence of the dimension X for different standards were analysed by comparing and using examples in order to strengthen comprehension of the dimension X of creepage distance and electrical clearance measurement for PTP and testing laboratory in electrical field. The results indicated that it was possible to cite standards between different groups as references according to equivalence in the future PT programs. Furthermore, different test items were carried out for lamps, information, electrical and other different product testing laboratories. Testing laboratories should pay attention to the working conditions specified in the instruction manual for accurately determine dimension X when participating in such programs.

Key words: Creepage distance and electrical clearance, Standards, Dimension X