Step-by-Step Guide to Earthing Installation for Plants

 

Earthing System 

Earthing systems, also known as grounding, form the backbone of electrical safety in industrial environments like manufacturing plants and factories. Proper earthing protects workers from electric shocks, safeguards equipment from faults, and ensures compliance with standards such as India's Central Electricity Authority (CEA) regulations and IS 3043. Faulty grounding contributes to over 20% of industrial electrical incidents annually, making it a priority for safety engineers. This guide expands on essential DO's and DON'Ts with practical steps, real-world examples from stainless steel processing units (common in Tamil Nadu), safety tips, and tables for quick reference.

Why Earthing Matters in Industry

Earthing provides a low-resistance path for fault currents to dissipate into the ground, tripping protective devices like circuit breakers. In a Tambaram factory, imagine a short circuit on a 415V motor panel: without earthing, the metal casing energizes at lethal voltage, endangering operators. With proper setup, current flows safely to earth (<1 ohm resistance), activating relays in milliseconds. Key benefits include:

• Personnel safety: Limits step and touch voltages to safe levels (<50V AC).
• Equipment protection: Prevents insulation breakdown and surges.
• Fire prevention: Diverts arcs away from flammables.
• Compliance: Meets Factories Act 1948 and CEA Measures for Safety (as per your expertise).

Recent audits show 40% of Indian plants fail earthling tests due to poor maintenance, leading to fines or shutdowns the safety gear.

Essential DO's for Installation and Maintenance

Adhering to these ensures long-term reliability.

1. Engage Qualified Professionals

Hire certified electricians (with IEEMA or DISCOM credentials) for design and install. Step-by-step:

1.     Conduct soil resistivity survey using Wenner 4-point method (e.g., 0.5-2 ohm-m in Tambaram red soil).

2.     Design per IS 3043: plate electrode (60cm x 60cm x 3mm GI) buried 3m deep.

3.     Install with supervision, documenting via photos and as-built drawings.

Example: In a Coimbatore steel mill, pros reduced resistance from 10 ohms to 0.8 ohms, averting a shutdown.

Safety tip: Verify credentials via PESO license; DIY risks invalid insurance.

2. Comply with Local Codes

Follow CEA 2010, State Department guidelines, and NBC Part 8. For TT systems (common in industries), max earth resistance is 5 ohms for LT.

3. Select Quality Materials

Use Cu-clad steel rods (16mm diameter, 3m long) for acidic soils or GI strips (40x6mm) for general use. Table below compares options:

For Example:

Material	Pros	Cons	Best For	Cost (per unit)
Copper Rod	Low resistance, corrosion-resistant	High cost	Sensitive electronics	₹2000
GI Strip	Affordable, easy bend	Rusts faster	Motors, panels	₹500/m
Chemical Earth	Maintains low resistance in dry soil	Needs periodic refill	Dry Tambaram areas	₹3000

 

Tip: Galvanize connections to IP65 rating for humid factories.

4. Ensure Proper Bonding

Connect all exposed metal (frames, ducts, cranes) via 25mm² Cu bus bar. Steps:

1.     Main panel: Bond neutral to earth via 2.5 ohm resistor if TN-S.

2.     Equipotential grid: 50x6mm ring around substation.

3.     Test continuity (<0.1 ohm) with micro-ohmmeter.

Example: A Chennai pharm plant bonded HVAC pipes, preventing stray currents from igniting solvents.

5. Inspect and Test Regularly

Quarterly checks per CEA. Practical protocol:

1.     Visual: Corrosion, theft, rodent damage.

2.     Measure resistance (fall-of-potential method).

3.     Continuity and insulation tests.

4.       For Example:

Test Type	Tool	Acceptable Value	Frequency
Earth Resistance	3-point Tester	<1 ohm (critical)	Quarterly
Soil Resistivity	Wenner Probe	<10 ohm-m	Annually
Bonding Continuity	Micro-ohmmeter	<0.2 ohm	Bi-annual

Tip: Log in Excel; flag >20% rise for refill with bentonite.

6. Dedicated Electrodes for Sensitive Gear

For PLCs or VFDs, use isolated earth pit (separate 80ft trench).

7. Label Clearly

Use engraved tags: "Earth Do Not Disconnect" at every joint.

Critical DON'Ts to Avoid Hazards

Ignoring these invites disasters.

1. No Amateur Installs

Improper setups cause 30% of shocks. Risk: High resistance leads to flashovers.

2. Avoid Undersized Conductors

Never use <16mm²; calculate per I²t fault energy.

3. Never Use Pipes for Grounding

Gas lines explode under fault; water pipes corrode electrolytically. CEA prohibits.

Example: A Virudhunagar foundry fined ₹5L for pipe grounding, causing pipe bursts.

4. Don't Skip Maintenance

Neglect doubles resistance yearly via corrosion.

5. Customize per Application

HV substations need grid; domestic needs rod.

6. Document Everything

Records prove compliance during audits.

7. No Unauthorized Changes

Modifications need HAZOP review.

Case Study: Factory Fix

A local stainless steel unit had 25-ohm resistance (faulty GI plate). Fix steps:

1.     Dug new chemical pit (2 no’s parallel).

2.     Added 50x6mm riser to panel.

3.     Tested: 0.5 ohm achieved.
Result: Zero shocks in 2 years, saved ₹2L in downtime.

Safety checklist:

• PPE: Insulated gloves during tests.
• Lockout-tagout before digs.
• Warn workers: "Earth Pit Work – No Entry."