We highly recommend that the safety rubber matting, even those held in storage, should not be used unless they have been electrically tested in accordance with the relevant standard within a maximum period of twelve months. Here are the Do's and Don't with High Voltage Insulating Mats.
The electrical insulating mats should not be exposed unnecessarily to heat or light or allowed to encounter oil, grease, turpentine, white spirit or strong acid. It should be placed on a clean, smooth floor and the feet should be positioned in the center of the electrical mat. When rubber matting becomes soiled, it should be [...]
Each time before use, the safety matting should be visually inspected. If the matting is thought to be unsafe, it shall not be used and should be returned for testing or destroyed.
Insulating mats should be properly stored to avoid the risk of damage to the insulating material. Care should be taken to ensure that the electrical matting is not compressed, folded, or stored in proximity to steam pipes, radiators or other sources of artificial heat or exposed to direct sunlight, artificial light or ozone for prolonged [...]