You've got the basic concept, but let's refine it for clarity and accuracy, particularly in the context of electrical safety.

Here's a more precise breakdown



Bonding

The intentional electrically connecting of all normally non-current-carrying metallic parts likely to become energized, creating a low-impedance path for fault current. Its primary purpose is

equipotentiality. You want everything at the same voltage potential, so that if a fault occurs, no voltage difference exists between different metallic parts that someone could touch, preventing or minimizing shock hazards. Grounding (Earthing)

Connecting the electrical system (typically the neutral point of the service transformer or generator, and often metallic enclosures) to the earth (ground) via a grounding electrode system (GEC = Grounding Electrode Conductor, often connected to things like ground rods, water pipes, or a concrete encased electrode). The primary purposes are:

Stabilizing Voltage to Earth

Keeps the voltage of the electrical system with respect to ground within predictable limits, preventing overvoltages that could damage equipment or pose a hazard.

Facilitating Overcurrent Device Operation

Provides a low-impedance path to ground that allows sufficient fault current to flow back to the source (transformer), causing an overcurrent protection device (circuit breaker or fuse) to trip quickly and clear the fault. This is where the bonding becomes crucial. If metallic parts are not properly bonded, the fault current path becomes high impedance, potentially allowing dangerous voltage to persist for a longer period and failing to trip the breaker.

Key Differences and Emphases


Purpose

Bonding is about equipotentiality to minimize shock hazards during a fault. Grounding is about stabilizing system voltage and facilitating fault clearing.2.

Scope

Bonding applies to all non-current-carrying metallic parts that could become energized. Grounding focuses on connecting the electrical system to earth (and also metallic enclosures).3.

The Connection to Ground

Bonding does not necessarily involve a direct connection to earth. While the grounded conductor is often connected to ground, the equipment grounding conductor (EGC) and the bonding conductors might connect to the grounding electrode system at the service entrance or other defined points, but their primary role is to ensure a low-impedance path back to the source for fault current.

Think of it this way



Bonding creates the superhighway for fault current. It ensures that if a fault occurs, the current can flow quickly and easily back to the source. Grounding is like a controlled leak to earth to stabilize voltage.

Important Considerations



Impedance

The impedance of the bonding and grounding paths is critical. Low impedance is essential for effective fault clearing and minimizing voltage rise during a fault.

NEC (National Electrical Code)

The NEC has very specific requirements for bonding and grounding, and understanding these requirements is crucial for safe electrical installations.

EGC vs. GEC

It's helpful to clearly differentiate between the Equipment Grounding Conductor (EGC) and the Grounding Electrode Conductor (GEC). The EGC runs with the circuit conductors and connects metallic enclosures back to the source (transformer). The GEC connects the grounding electrode system (ground rods, etc.) to the service equipment (and potentially the grounded conductor/neutral).

System Grounding vs. Equipment Grounding

System grounding refers to grounding the neutral point of the power source (e.g., transformer). Equipment grounding refers to grounding the non-current-carrying metal parts of equipment. Both are critical for safety.

In summary, your initial definitions were on the right track, but the above clarifies the distinctions and purposes more accurately. Emphasizing equipotentiality as the goal of bonding, and fault current path back to the source as a result of grounding are key to understanding the difference. Flag for review