Earthing Types

Earthing Types

http://groups.google.co.uk/group/uk.d-i-y/msg/14a0b8a90fca226b

BS 7671 lists five types of earthing system:

 TN-S 
 TN-C-S 
 TT 
 TN-C
 IT 

Where those letters each indicate:

 T = Earth (from the French word Terre)
 N = Neutral
 S = Separate
 C = Combined
 I = Isolated

A useful link to an IEE PDF on the subject (presumably most DIYers can ignore the section on earthing caravan pitches) [1]