In the TN-C power distribution system, the neutral and the protective earth functions are
combined in a single conductor.
A
Power system earth
B
Exposed conductive parts
Network type TN-C-S (Terra Neutral-Combined-Separate) :
In the TN-C-S power distribution system, the neutral and the protective earth functions are
combined to some degree in a single conductor, a direct earth to the exposed conductive parts of
the installation exists in part. The connection is achieved through the PEN conductor.
A
Power system earth
B
Exposed conductive parts
Network type TT (Terra Terra) :
The TT power distribution system has one point that is directly earthed. In addition, the exposed
conductive parts of the installation are connected to earth electrodes that are independent from
the power system's earth.
Instruction book
AIF999999
51