Optimization of power equipment lifecycle is one the most important problems of power system management. At the first stage of analysis an expert judgement is a key element in the smooth transition from preventative maintenance system to condition monitoring under the present technological conditions of grid equipment diagnostics. A comparative analysis of experts judgements consistency during electrical equipment diagnostics is described in this study. The research have shown that conclusions can be made concerning reasons of some failures with appropriate signs of transformer or switching equipment failure, as well as with fuzzy linguistic estimates of the signs made by experts. The considered examples show the possibility of precedence ranking of reasons for pre-failure state, which is defined by the membership function values within the range from 0 to 1. Credibility of the result is achieved through the expert judgements consistency, setting fuzzy relations between criteria and possible reasons of the defects. In connection with the above results, the research of real recommendations to use the statistics methods for expert judgements analysis depending on the real technical state of electrical equipment. Also, the study provides the comparative analysis of mean and median rankings of experts judgements consistency using the Kemeny median method.