What types of RCDs are typically used in residential installations?

In residential installations, the commonly used types of Residual Current Devices (RCDs) are Type AC, Type A, and sometimes Type B.

Type AC RCDs are designed to detect sinusoidal alternating currents and are suitable for standard household circuits where the load does not produce pulsating DC. Type A RCDs have the capability to detect both alternating current and pulsating direct current, which makes them ideal for circuits that may include devices such as modern appliances with electronic components or variable speed drives, which could create residual currents that are not purely sinusoidal.

Type B RCDs, while often utilized in commercial or industrial settings, can occasionally be found in residential contexts especially if specific appliances that generate smooth direct currents, such as electric vehicle chargers or photovoltaic systems, are in use.

The other options include types that are either not typically used in residential contexts or do not exist within the RCD classification. For instance, Type C, D, E, F, G, H, and I are not standard classifications for RCDs in a residential setting, making them less relevant to the question. The focus on Type AC and Type A in residential installations aligns with safety regulations and the types of appliances most commonly found in homes.