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When a fault occurs,
where does current go?

Choose a familiar situation and follow the current back to its source. Compare what happens with a working protective path and when protection is missing.

Illustration for discussion · not a site design

Show a client what changes.

Normal current returns through neutral. The protective wire is available if a fault occurs.

Earthing arrangement
Fault current completes a return loop to the sourceA supply feeds a metal enclosure through a protective device. With a fault present, the intended return is either a metallic protective conductor in TN-S or electrodes and soil in TT. A broken conductor interrupts that intended path.SUPPLYSource connection METAL ENCLOSURE Protective deviceNeutral · normal return Protective conductor (PE)Electrodes & soil (TT return path) !A fault needs a complete circuit.Change the conditions. See which protective path is available.
Conceptual circuit, not wiring instructions. The animation is deliberately slowed down; it does not show a verified disconnection time.
Line: supply to equipmentNeutral: normal returnPE: protective return

What should your client remember?

Fault current needs a return circuit to its source. Earthing and bonding provide protective paths; correctly selected protective devices must disconnect the affected circuit. A ground electrode alone does not prove safety.

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Read the result correctly

TN-S uses the illustrative relationship I = 230/Zs. TT uses I = 230/(RA + RB), with an assumed source electrode RB = 20 Ω and other impedances omitted. These are teaching assumptions, not site values. A B16 magnetic band is not a complete disconnection-time assessment.

TT RCD behavior is a simplified residual-current illustration. Actual selection and testing must consider the full installation, RCD type, characteristic, permitted touch voltage and disconnection requirements. Schneider Electric: TT principle · TN principle.