How to select a residual current device

RCCBs and RCBOs are classified in different categories according to their suitability to grant protection against several types of earth fault currents.

Type AC

Sinusoidal alternating residual current

They are suitable for all the installations with potential sinusoidal earth fault currents.

They are aimed to protect from linear loads, such as electric ovens, hair-dryers, tungsten/halogen lighting, electric heating.

Type A

Same features as type AC + pulsating direct current

They are aimed to protect installations provided with electronic devices for rectifying current or for phase-cut regulation of a physical quantity (temperature, speed, light intensity, etc.), directly fed by the network without interposition of transformers and insulated according to class I. It’s the typical form of earth fault currents of single-phase devices containing diodes, dimmers for lamps’ regulation, rectifier bridges of various types.
TV. Microwaves, PC, printers, electronic weighing machines, induction ovens, single-phase UPS.

Type A-HI

Same features as type A + high resistance to unwanted tripping

They are suitable to protect installations with electronic loads such as fluorescent lamps, data-centers, electronic ballasts, anti-noise filters.

They are suggested when service continuity is a must (hospitals etc) and they also grant functioning of main loads (fridge, etc) in case of lightning in residential applications.

Type F

Same features as type A-HI + detection of fault currents with mixed frequencies up to 1kHz

They are the ideal solution in case of loads with single-phase inverters (for example these are common in most of modern household appliances).

Typical applications are industrial and domestic appliances with single-phase inverter motor, such as: washing machines, air conditioning, heating pumps, dryers, dishwashers.

Type B

Same features as type F + smooth DC currents

Their purpose is to protect three-phase systems and appliances of class I which contain electronic circuits that, in the event of a ground fault, may generate smooth DC currents or high frequencies.

Lifts, ventilation systems, EV charging, PV, inverters for speed control, UPS, molding machines.