[rainbowzootsuit]

This must be a European design. In the USA, governed by NFPA 70 - The National Electric Code, the ground rod's purpose is to establish the ground voltage reference to reference the electrical systems of a building to it and to dissipate any charge buildup on the circuits.

The ground rod is not there to carry current to interrupt a fault to "protective earth" - the green or green/yellow. The circuit breaker interrupts a short as you bring the protective earth wire back to the main disconnect of a building where it bonds to the neutral wire.

If a fault occurs, an unregulated amount of current flows on the protective earth wire to the breaker panel and a circuit breaker interrupts the circuit.

[magicalhippo]

I'm no expert, but here in Norway we predominantly have IT systems[1], though new installations are mainly TN.

In the IT systems, the protective earth is not bonded to the neutral. Thus in case of a fault, the protective earth should be low impedance to ground so that the circuit breakers trip. At least that's my understanding.

[1]: https://aktif.net/en/types-of-earthing-systems/#IT_System

[rainbowzootsuit]

Thanks for the link. I don't know all the symbology there so it will take some reading up.

[taneq]

Technical nitpick, if it detects earth leakage and trips based on that, it's an RCD, not just a circuit breaker. Otherwise yeah, there's different approaches to earthing - in Australia for domestic stuff we have mandatory RCDs which work as you describe above, but then also in industrial/mining settings we have the big green/yellow cables which will directly sink current (potentially hundreds of amps) to ground, hopefully stopping you from getting bitten.

[rainbowzootsuit]

A thermal breaker won't trip on leakage current or arc faults either. I was trying to describe the classic "dead short" that will trip a thermal circuit breaker or fuse without the circuitry for arc or leakage detection.