Consider a high specification conductive grease if you are seeking to ensure a path to earth in a component or device. Any rotating component supported by ball bearings is essentially isolated from the rest of the device by the lubricant in the bearing raceway, so a conductive bearing grease would be the solution to avoid the build up of static electricity.
A non-conductive lubricant allows static charges or arcs to pit the rolling elements which accelerates wear. With a conductive grease the charge passes through the bearing with minimal electrical damage and often motor life is also extended. A synthetic electrically conductive grease will give you increase temperature capabilities and temperature stability, also better performance and much improved functional life.
Please take a look at the various conductive grease related articles below, including test videos, theory and product selection help.