Choosing an RCD: Tips and Tricks

First1 of all, it is desirable to pay attention to the total leakage current. Usually it should not exceed a third of the rated current of the RCD. If there is no data on leakage currents (which most often happens), then it is necessary to navigate with the calculation of 0.3 mA per load ampere.

It is advisable to buy RCD, which is able to disconnect not only the working conductors (phases), but also the neutral wire. In this case, there is no need to purchase an additional zero overcurrent protection device.

In the wiring area that is controlled by the RCD, the neutral wire should not be connected to the "ground"; and protective neutral conductor. In addition, the residual current device must be selected in such a way

so that it remains operational during sudden voltage drops for a short period of time (up to five seconds).

Modern RCD must necessarily guarantee reliable switching of the existing load. In this case, probable congestion in the network should be taken into account.

It should be borne in mind that some RCD models have overcurrent protection, while others do not. Priority should be given to devices that provide this protection.

If the RCD is installed in a residential building, then it is necessary to choose a class "A" device that will respond to pulsating and alternating currents of probable damage.

It is advisable to install an RCD in groups of networks where there are power outlets. For lighting lines, the installation of an RCD is usually not required.

To control leakage in rooms with high humidity, for example, in showers, bathrooms, it is necessary to select an RCD with a trip current of up to 10 mA, but only if a separate line is allocated for them. For other rooms, the operation current should not exceed 30 mA.

In principle, the above recommendations should be enough to select a quality device that can protect the whole family from the dangerous effects of electric current.