​​​​​​​​​​​Figure 1 - Conceptual difference between grounding (earth reference) and bonding (equalizing potential).

 

What is Grounding?

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Grounding connects an electrical system or equipment to the earth. Its purpose is to:

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• Provide a reference point for system voltage.

• Safely dissipate fault currents into the earth.

• Stabilize voltage during normal operation.

• Reduce lightning and static discharge hazards.

 

In high-voltage systems, grounding grids, rods, and conductors must be properly sized and interconnected to handle fault energy and step/touch potential hazards.
 

​What is Bonding? 

 

Bonding is the intentional connection of conductive parts to eliminate voltage differences between them.

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Bonding:

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•  Ensures metal parts stay at the same electrical potential.

• Reduces shock hazards during faults.

• Prevents arcing between equipment enclosures and structures.

• Supports proper clearing of overcurrent devices.

 

Bonding does NOT imply connection to earth; it is equipment-to-equipment or structure-to-structure equalization.
 

Why Grounding and Bonding Must Work Together

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Grounding alone cannot prevent shock hazards if equipment housings or structures become energized. Bonding alone cannot dissipate fault current safely. Together, grounding and bonding:

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• Create low-impedance fault paths.

• Ensure breakers and protective devices operate quickly.

• Minimize step/touch voltage during faults.

• Reduce induced voltages near high-voltage lines.

 

Common Grounding and Bonding Mistakes

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• Loose or corroded bonding connections.

• Using the earth as a current-carrying conductor.

• Broken or missing equipment grounding conductors.

• Improperly sized grounding electrode conductors.

• Bonding only at one location (creates potential differences).

• Failure to bond fences, gates, and metallic structures in substations.
   

High-Voltage Applications (Substations, Switchyards, Transmission)

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• Ground grids are engineered to control fault current distribution and step/touch potential.

• All metallic structures, including fences, must be bonded to the grid.

• Portable grounds must be applied in the correct sequence: ground end first, line end last.

• Equipotential grounding reduces risk during maintenance on de-energized circuits.

• Induced voltages can energize conductors—bonding and grounding mitigate this risk.

 

​Emergency Response

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• Do not touch a person in contact with energized equipment – de-energize first.

• Maintain safe clearance until power is confirmed off.

• For shock victims: call emergency services and begin CPR/AED if trained.

• For arc injuries: use dry, sterile dressings and avoid ointments.

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Discussion Questions

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• Are grounding and bonding connections intact and properly sized?

• Are we using equipotential grounding for de-energized tasks?

• Do temporary grounds meet the correct sequence of application?

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RATTLIR Takeaway

 

Grounding protects equipment. Bonding protects people. Understanding and applying both ensures we strike before it bites – especially around high-voltage systems.