This document discusses different earthing systems used in electrical installations. It describes the TN-S system where the earth terminal is connected to the star point of the secondary winding of the supply transformer. It also describes the TN-C-S system which uses a combined protective and neutral conductor. The document recommends using multiple earthing rods planted in moist soil with iron fillings to reduce earthing resistance for safety and to provide a current return path to ground.

2. 

3. 
 Clear from the noise of high or low frequency,not
have risk of neutral broken or failure
 Suitable for special application like
telecommunication.
 Suitable for premises where all AC power circuits
are residual current device (RCD) protected.
ADVANTAGES

4. 
TN-S SYSTEM

5.  Used for underground power supply to the premise
or factory from the distributor substation to
customer substation.
 Earth terminal is connected by the supply protective
conductor (PE) back to the star point (neutral) of the
secondary winding of the supply transformer, which
is also connected at that point to an earth electrode.

6. 
TN-C-S SYSTEM

7. 
 Combined earth and neutral system called the
‘protective and neutral conductor’ (PEN) or the
‘combined neutral and earth’ conductor (CNE).

8. 
 Plant in moist places
 Sprinkle iron fillings around the electrode.
 Electrode holes
 Plant two parallel rod electrodes
 Insulation resistance test.
REDUCING EARTHING
RESISTANCE

9. 
 Fire when leakage current
 Electrick shock
 Current return path to ground
 Safety for customers.
USE OF MULTIPLE
EARTHING