Patti is the common trade and site word for an earthing strip - the flat bar used to interconnect electrodes and bond equipment. An earthing patti size is written the same way as a strip: width x thickness in millimetres. The usual GI patti sizes are 25 x 3, 25 x 6, 32 x 6, 50 x 6 and 65 x 10 mm.
Common GI earthing patti sizes
| Patti size (mm) | Where it is used |
|---|---|
| 25 x 3 | Panel and sub-distribution earthing |
| 25 x 6 | Distribution boards and small plant |
| 32 x 6 | LT panels and machinery bonding |
| 50 x 6 | Main earth grid and risers |
| 65 x 10 | Substations, power plants and HT grids |
How to choose a patti size
Pick the patti by the fault current it must carry for the clearing time, exactly as for a strip - see the earthing strip size chart and the current-carrying-capacity guide. Copper patti is used where fault current, life or HV conditions demand it; GI patti is the economical default for general earthing.
