Diesel Generator Backup Supply
A standby generator feeding emergency lighting and an alarm, earthed to its own rod. Backup generation is a small installation in its own right, with its own earth reference.
Components Needed
Text Wiring Path
Generator L → MCB → Light + Siren Light/Siren N → Generator N Generator PE → Earth Rod
Schematic
Steps
- 1Place a diesel generator as the source, with an earth rod below it.
- 2Place an MCB on the generator's live output, then an emergency light and an alarm siren.
- 3Wire the generator Live through the MCB to both loads.
- 4Return both neutrals to the generator N terminal.
- 5Run the generator's PE conductor down to the earth rod.
- 6Press Run: both loads energise. Break the earth path and read the warning that appears.
A generator is the origin of its own installation, so its protective devices need an earth reference to fault against — here a rod, a TT arrangement. Changeover must be interlocked: back-feeding the network can kill someone working on the cable.
A generator must never back-feed the supply network — that can energise the incoming cable and kill a linesman working on it. Use an approved changeover arrangement, and earth the generator to its own rod so its protective devices have a fault path.
Terms used here
Defined in the glossary — each one opens at its own entry.
Now wire it for real.
Build this circuit in the browser, inject a fault, and watch the protection respond.