Overview of Residual Current Devices (RCD)
When choosing a residual current device (RCD), attention should primarily be paid to the total leakage current. Typically, this should be more than one-third of the rated current of the RCD. In the absence of leakage current data, which is quite common, it is recommended to use a calculation of 0.3 mA per one ampere of load.
Types of RCDs and Their Functions
It is recommended to purchase RCDs capable of disconnecting both live (phase) and neutral conductors. This will avoid the need for additional devices to protect against overloads in the neutral circuit.
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Installing RCDs in Electrical Wiring
In the wiring zone controlled by the RCD, nothing should be connected to the "earth" or protective neutral conductor. It is important to choose a device in such a way that it remains operational even during sharp voltage fluctuations over short periods of time (up to five seconds).
Modern RCDs should provide reliable load switching. It is important to consider potential loads in the electrical network.
One should not forget that some models of RCDs contain overload protection, while others do not. It is recommended to prefer devices that have this protection.
Choosing RCDs for Specific Conditions
If the RCD is installed in a residential building, it is advisable to choose a class "A" device that reacts to pulsating and alternating currents, probably related to faults.
Installation of RCDs is recommended in groups of networks where power outlets are located. For lighting lines, such a solution is usually not mandatory.
For rooms with high humidity, such as showers or bathrooms, it is advisable to choose RCDs with a trip current of up to 10 mA, provided that a separate line is allocated for them. For other rooms, the trip current should not exceed 30 mA.
Conclusion
In general, the above recommendations are sufficient to choose a quality device capable of protecting the entire family from dangerous electrical currents.