In short. Earthing connects the installation to the ground. Bonding connects metal parts to each other so that no dangerous voltage can appear between them. Together they limit touch voltage during a fault, give protection a path to operate, and reduce noise and surge damage.
Purposes
- Safety: limit touch and step voltage during faults.
- Protection operation: provide a low-impedance return so devices trip.
- Equipotential zones: keep exposed metalwork at similar potential.
- Surge and lightning: give surge energy a safe path. See lightning and SPD coordination.
- Signal integrity: functional earth for controls and communications.
Elements of the architecture
| Element | Role |
|---|---|
| Earth electrodes | Connection to ground. See electrode engineering |
| Main earthing terminal / bar | Central connection point |
| Protective conductors (PE) | Carry fault current from equipment to source |
| Main equipotential bonding | Connects incoming services, structure, pipes |
| Supplementary bonding | Extra bonding in special locations |
| Neutral-earth link | Defines system earthing. See neutral-earth architecture |
| Functional earth | For electronics and shielding |
Generator installation
- Bond the generator frame, alternator, control panel, fuel tank, exhaust and mounting to the earthing system.
- Connect the generator neutral according to the system earthing design.
- Use flexible, appropriately sized bonding across anti-vibration mounts.
- Bond containers and canopies, with continuity at doors and panels.
Design and test steps
- Choose the earthing system and electrode design.
- Size protective conductors for the fault current and clearing time.
- Plan equipotential bonding including structure and services.
- Separate clean and noisy earths where needed, joined at a single point.
- Test continuity, electrode resistance and loop impedance. Retest at intervals.
Illustrative example
A generator in a canopy has a frame earth cable to the site earth bar, a separate bond across the canopy panels, and a neutral link inside the control panel. Continuity tests show a high-resistance joint at the canopy door, which is fixed with a flexible bond. Without the check, a fault could leave the door live at a dangerous voltage.
Three jobs of an earthing system
- Safety: limit touch and step voltage during faults.
- Protection: provide a low-impedance return path so devices trip.
- Performance: give a stable reference for electronics and a route for surge and noise currents.
Building blocks
| Element | Role |
|---|---|
| Earth electrodes | Connect the system to the ground mass |
| Main earthing terminal | Common point for bonding |
| Protective conductors | Carry fault current back to the source |
| Equipotential bonding | Keeps exposed metalwork at similar potential |
| Functional earth | Reference for signal and communications equipment |
Equipotential bonding
Bond generator frame, switchboards, cable trays, fuel tank, exhaust, building steel and incoming services to the main earthing terminal. Without bonding, a fault can create dangerous voltage differences between nearby metal parts.
Generator specific issues
- Whether the set neutral is earthed at the generator or at the main board.
- Skid and enclosure bonding.
- Separate earth pits for dedicated electronics where site policy requires, tied together at one point.
Verification
Measure earth resistance and continuity of protective conductors. Retest periodically and after civil works. See electrodes and soil resistivity and earthing system study.
Common mistakes
- Painted or corroded bonding joints.
- Multiple unplanned earth connections that form loops.
- Generator frame not bonded.
What to send us
Send site layout and earthing details. Send your application details. See also earthing basics.
Questions engineers ask
What is the difference between earthing and bonding?
Earthing connects to the ground. Bonding connects metal parts to each other.
Does a generator need its own electrode?
It is normally connected to the site earthing system, with electrodes as the design requires.
What is equipotential bonding?
Connecting conductive parts so that voltage differences between them are small.
How often should earthing be tested?
Periodically, per local rules and site policy, and after any change.
This guide gives general principles. Earthing design must follow local regulations.