The way that an earthing mat works: When an electrical fault occurs in a circuit, the fault current will flow through the earth mat and into the ground. The earth mat is designed to have a very low resistance path to electrical current, which allows it to safely and efficiently dissipate the fault current into the ground. This helps to earth not only the fault current inside the system but also lightning, external voltage surges, etc which thereby protects from electrical shocks and prevents damage to the electrical system.