In country areas, electricity suppliers often use a different method of earthing the system known as PME (Protective Multiple Earth). In this method, the earth leakage current is fed back to the electricity board's sub-station along a neutral return wire, and then to earth.
Regulations regarding the PME method of earthing are very stringent and cross bondings to gas or water services usually need to be larger. If you are in doubt about the type of earthing method used in your area, always check with your local electricity supplier.
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