SIZE OF EARTH LEADS



SIZE OF EARTH LEADS :

For Transformer Neutral Point Earthing :

Transformer
Rating

Electrolytic bare copper condutor or strip

Insulated (PVC Signle Core Stranded aluminium

Galvanised Iron Conductor Or Strip

50 KVA& below

8 SWG

16 Sq.mm

25mm/3mm

63 KVA/75/ KVA

8 SWG

25 Sq.mm

40mm/6mm

100 KVA

4 SWG

35 Sq.mm

40mm/6mm

150 KVA/160 KVA

2 SWG

70 Sq.mm

40mm/6mm

200 KVA

25mm x 1.5mm

95 Sq.mm

40mm/6mm

250 KVA

25mm x 3 mm

225 Sq.mm

40mm/6mm

300 KVA

25mm x 3mm

225 Sq.mm

40mm/6mm

500 KVA

25mm x 6mm

300 Sq.mm

50mm/6mm

750 KVA

25mm x 6mm

300 Sq.mm

Above 500 KVA only Coper / Aluminium Strips to be used

Above 750 KVA size of earth to be determinal as per IS : 1886 – 1967

For Equipment Earhing:

(Applicable to Transformer , Mortors Generators , Switchgeras etc.)

Rating 400-V, 3ph 50 cy equipment in KVA

SIZE OF EARTH CONDUCTOR

Bare Copper

Aluminium PVC insulated

Galvanised Iron wire/strip

upto 5

14 SWG

6 Sq.mm

22-Jul

6 to 15

10 SWG

16 Sq.mm

8 SWG

16 to 50

10 SWG

16 Sq.mm

25 mm x 1 1/2 mm

51 to 75

8 SWG

25 Sq.mm

25 mm x 1 1/2 mm

76 to 100

6 SWG

35 Sq.mm

25 mm x 3 mm

101 to 125

4 SWG

50 Sq.mm

25 mm x 6mm

106 to 150

2 SWG

70 Sq.mm

25 mm x 6 mm

 

25 x 1 1/2 MM

   

151 to 200

25 x 1 1/2 mm

70 Sq.mm

38 mm x 6mm

201 and above

25 x 3mm

185 Sq.mm

50 mm x 6 mm

Note:

Conductor be Protected so that no mechanical damage could be caused. Earth connections for all H.V. equal and switch gear should not be less than 62.5 Sq.mm copper or 185 Sq.mm PVC insulated standard aluminium conductor or      50 x 6mm G.I Strip.

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