RCD / RCCB: Types AC, A, F and B
Residual current devices (RCDs) detect leakage currents in an electrical installation and disconnect the circuit when a potentially dangerous fault is detected.
There are different RCD types AC, A, F and B. Each type is designed for different electrical loads and residual current waveforms.
Type AC RCD
Type AC detects sinusoidal AC residual currents.
What is it used for?
Suitable for simple circuits with little or no electronic equipment.
Typical applications: conventional lighting, resistive heating and basic electrical loads.
Examples available from Components4Automation:
Hager CDC240P 2P 40A 30mA
Legrand 411661 4P 40A 30mA Type AC
Type A RCD
Type A detects AC residual currents as well as pulsating DC residual currents.
What is it used for?
Suitable for many modern electrical and electronic appliances, including household appliances, hobs and power supplies.
Typical applications: hobs, washing machines, power supplies, LED lighting and other electronic equipment.
Examples available from Components4Automation:
Siemens 5SV3314-6 2P 40A 30mA Type A
Schneider A9R31240 2P 40A 30mA A-SI
Legrand 411675 4P 40A 30mA Type A
Type F RCD
Type F includes the protection provided by Type A and can also detect mixed-frequency and higher-frequency residual currents.
What is it used for?
Suitable for heat pumps, air conditioning systems and equipment with electronic speed control.
Typical applications: heat pumps, air conditioners, variable-speed motors and certain EV charging applications.
Examples available from Components4Automation:
Legrand 411592 2P 63A 30mA Type F
Hager CDF540A 2P 40A 30mA Type F
Type B RCD
Type B also detects smooth DC residual currents, in addition to the residual currents covered by the previous types.
What is it used for?
Used in more demanding applications such as EV chargers, variable frequency drives, UPS systems and industrial equipment.
Typical applications: EV charging, frequency converters, UPS systems, power converters and industrial installations.
Example available from Components4Automation:
Hager CDB525E 2P 25A 30mA Type B
Which RCD type should you choose?
The choice between Type AC, A, F or B depends on the equipment connected to the circuit and the manufacturer's recommendations.
Browse our range of RCDs and RCCBs and choose the right protection for your electrical installation.
