§531 — Residual Current Devices (RCDs)

Types

Type	Detects	Application
AC	Alternating current (sinusoidal)	Obsolete, no longer permitted for new installations
A	Alternating current + pulsating DC	Standard for residential buildings
F	A + high-frequency components	Frequency inverters (single-phase)
B	A + pure DC	Charging stations, frequency inverters (three-phase)

30 mA — personal protection in dwellings, bathrooms, outdoors (§411.3.3, §701, §708).
100 / 300 mA — fire protection in agriculture (§705), industry.
500 mA — distribution only, no personal protection.

RCD before the final circuits, after the main fuse.
Test button at least once every six months (recommendation: quarterly).
No shared neutral conductors between different RCD groups.
Cumulative leakage currents must remain < 30% of I∆n; otherwise, use type B or multiple RCDs.