The CIGRE Working Group A3.43 has published the technical brochure (TB) 953 Tools for lifecycle management of T&D switchgear based on data from condition monitoring. This work is a continuation of the previous working group that produced the CIGRE technical brochure 737 and it builds on other ones as well. The main objective is to develop a method for assessing the condition of the switchgear, considering mechanical, dielectric and electric wear as well as the functioning of the auxiliary circuits. It covers both transmission and distribution (T&D) equipment.One of the results is a large table that shows the correlation between condition indicators and degradation mechanisms. Based on data mining of that table, we propose the monitoring of 23 condition indicators out of 39 ones. This table is part of a systematic approach for lifecycle management of switchgear. A systematic methodology is outlined to group the potential degradation mechanisms and derive a well-defined conservative subset of 23 condition indicators out of the total set of 39, thereby providing a coherent strategy to minimize the number of sensors required to be installed for condition assessment of switchgear.