Residual current

Also known as earth leakage current

Residual current is the imbalance left when current in a circuit does not return through the same intended conductors that supplied it.

Residual current is the imbalance left when current in a circuit does not return through the same intended conductors that supplied it. In everyday single-phase terms, an RCD looks for a difference between current in line and neutral. Electrical Safety First explains that an RCD monitors current in the circuits it protects and switches off quickly if it detects electricity flowing down an unintended path. IET model forms record RCD type, rated residual operating current and measured operating time, while EV charging guidance also uses DC residual current wording.