Lightning, Arrestors Earthing, LT Distribution Box
Pipe earthing or rod earthing is given for the distribution substation. Three electrodes creating an equilateral triangle are given so that adequate earth buffer is available.
11 kV lightning arrestors 9 (kV) of outdoor type are used for diverting the lightning surges to earth resistance of earth. A lightning arrestor should be installed on the HT side and its lead should be remain at a minimum.
LT Distribution Box
For transformers of 100 kVA and above, sheet metal LT distribution box consisting of LT breaker and fuse cut-outs is given from where distribution feeders are to be taken out. The size of the box has to be suitable for accommodating MCCB, fuse cut-outs, bus-bars, cable connectors and etc.