Earthing guideline for hazardous area

Earthing guideline in hazardous area

Earthing is required for –

·         Safety of working personnel

·         Equipment safety

·         Protection against fault

earthing in hazardous location

Size of earth conductor

Sr.no.	Type of equipment	Earth conductor size
1	Street light poles	10 mm dia solid GI wire rope
2	Motor upto 3.7KW	8 SWG solid GI wire
3	Motor upto 5.5KW to 30KW & welding receptacle	10 mm dia solid GI wire rope
4	Motor above 37KW including HT motor	16 mm dia solid GI wire rope / 40mm x5 mm GI strip
5	Building columns	40mm x 5 mm GI strip
6	Storage tank vertical or horizontal	40mm x 5 mm GI strip
7	Loading racks	40mm x 5 mm GI strip
8	Pipe racks, heat exchanger, Vessel	40mm x 5 mm GI strip
9	Small equipments and instruments	8 SWG solid GI rope
10	Lighting, power and instrument panel	10 mm dia solid GI wire rope
11	Main earth bus /MV &HV switchgear interconnection /power transformer	As per calculation
12	EHV/HV substation	As per calculation
13	Push button station	8 SWG solid GI wire
14	Bonding of pipe	25 mm2 insulated flexible copper cable
15	Lighting transformer	16 mm dia solid GI wire rope

General:

1. Earth connections to individual equipment from nearest earth plate/ grid may also be done alternatively using Aluminum/ Copper conductor PVC insulated core of size not less than half the cross-section of respective power cable to the equipment (Motor, Panel etc.). Connections shall be made using crimped type of lugs.

2. Earth rods and conductors shall be designed to cope with the conditions imposed. The earth conductor shall be adequately sized to carry the applicable maximum earth fault current without undue temperature rise. All joints shall be protected against corrosion.

3. All the electrical equipment operating above 250 volts shall have two separate and distinct connections to earth grid.

4. Lighting Fixtures shall be earthed through the extra core provided in the lighting cable.

5. The cross sectional area of earthing conductor shall be minimum 4 sqmm.