Our DFS Type F residual current circuit-breakers are sensitive to mixed frequencies and reliably protect against sinusoidal AC residual currents, pulsating DC residual currents at the mains frequency, and residual currents with multiple frequency components not equal to 50 Hz. Furthermore, they are short-time delayed and lightning-resistant. This reduces the risk of unwanted tripping caused by inrush or surge currents, for example during thunderstorms or due to ballasts.

You can find our Type F residual current circuit-breakers here.
You can find our Type F residual current operated circuit-breakers with integral overcurrent protection (RCBOs) here.

But: Which type of RCD is the right one, and when should it be used?

Since 1984, residual current circuit-breakers have been mandatory for rooms containing a bath or shower (DIN VDE 0100-701). Since 2007, all socket circuits up to 20 A Indoors and up to 32 A outdoors that are accessible to members of the public without electrical training must be protected by a residual current operated protective device (RCD) with a rated residual current of no more than 30 mA (DIN VDE 0100-410). The requirements were further expanded in 2018 to include indoor socket circuits up to 32 A and lighting circuits in flats. And now, according to the revised version of DIN VDE 0100-701, permanently connected water heaters must also be protected by an RCD.

Guidance on the type of residual current circuit-breaker (RCCB) that must be used is provided, among other places, in DIN VDE 0100-410 and DIN VDE 0100-530. Accordingly, the use of AC-type RCCBs (for protection against pure sinusoidal AC residual currents) is no longer permitted in new installations. Wherever only sinusoidal AC and pulsating DC residual currents can occur, a Type A RCD is sufficient.

Type F residual current circuit breakers are suitable for AC and pulsating DC residual currents at the rated frequency, as well as for AC residual currents with mixed frequencies up to 1 kHz. They were incorporated into DIN VDE 0100-530 in 2018.

This became necessary because many modern electrical appliances use single-phase frequency converters for stepless speed control. Adding to this are appliances with switching power supplies. In the event of a fault, both of these types of equipment can also generate residual currents with mixed frequencies other than 50 Hz. This applies, for example, to washing machines and dishwashers, heat pumps, fridges and LED lighting. Type A RCCBs cannot detect mixed frequencies and do not trip.

Our DFS Type F RCCBs are mixed frequency sensitive and therefore also offer reliable protection against residual currents with mixed frequencies. Unlike Type A RCCBs, they remain operational in the presence of smooth DC residual currents of up to 10 mA. Furthermore, they are short-time delayed and lightning-proof. This reduces the risk of unwanted tripping caused by inrush or surge currents, for example from ballasts or during thunderstorms, thereby ensuring in greater system availability.

Where space is limited, our mixed frequency sensitive DRCBO 3 F (two-pole) or DRCBO 4 F (four-pole) are ideal for organising the layout of the electrical installation and increasing system availability.

Our recommendation

• Type A for lighting circuits that still use incandescent bulbs, and for socket circuits where only conventional appliances areconnected.
• Type F wherever appliances with single-Phase frequency converters, single-phase Inverter motors or switching power supplies are used – the ideal residual current protection for the modern home.