Determining the correct class of electrical mat involves checking the electrical apparatus that you are working with. The equipment will have a tested and working voltage range indicated on the equipment and the recommended standard that it has been tested under.
Always consult an electrical engineer before purchasing any electrical switchboard safety matting to ensure any product you purchase is suitable for the equipment being worked on.
DO NOT ASSUME that 1 type and class will suit similar pieces of equipment in the same area.
CHECK each piece of equipment that you are purchasing the matting for to ensure suitability.