| Type of ground network | Description |
| TN-ะก | TN system in which protective and neutral conductors are grouped into one conductor along the whole length of system. |
| TN-S | TN system in which protective and neutral conductors are isolated from each other. |
| TN-C-S | TN system in which protective and neutral conductors are grouped into one conductor at the advance section, but further protective and neutral conductors are isolated from each other. |