Earthing Types
Earthing Types
BS 7671 lists five types of earthing system:
- TN-S
- TN-C-S
- TT
- TN-C
- IT
Where those letters indicate:
- T = Earth (from the French word Terre)
- N = Neutral
- S = Separate
- C = Combined
- I = Isolated
An explanation can be found here.
A useful IEE document on earthing (presumably most DIYers can ignore the section on earthing caravan pitches)
You can find details on installing a TT earth here.