GFCI is American for RCD, more or less. Except that our GFCIs are almost always 5mA, whereas yours seem to mostly be 30mA. And ours don’t generally live on DI

GFCI is American for RCD, more or less. Except that our GFCIs are almost always 5mA, whereas yours seem to mostly be 30mA. And ours don’t generally live on DIN rails. The rule here is that, if you replace an old ungrounded outlet, you ought to find a way to ground it and, if you can’t, you must add a GFCI. (Sadly this often can’t be done in the breaker box, so it means a GFCI in the receptacle. The issue with adding GFCIs in the breaker box is that a lot of old knob and tube installations didn’t match up neutrals with their corresponding hots, so individual circuits don’t have circuit-specific neutrals to run through the GFCI.) American GFCI breakers generally look like this: https://www.homedepot.com/p/Square-D-Homeline-20-Amp-Single-Pole-GFCI-Circuit-Breaker-HOM120GFICP/100002959 https://www.homedepot.com/p/Square-D-Homeline-20-Amp-Single-...