How to choose an RCD for the house and apartment?
The importance of the event
If you choose the RCD model incorrectly, that is, make a mistake with its characteristics, this is fraught with the following consequences:
- Automation will be triggered during a false alarm, as Minor leakage of electricity is always present in the wiring, especially if it is old (in a wooden house in the country).
- Too high characteristics of the RCD in terms of power, to which you give preference, will not work during a dangerous situation, as a result of which an electric shock can be obtained.
- The device will not be able to function when connecting the aluminum conductors of your home wiring, because most modern models are designed only for connecting copper conductors.
In order to prevent these errors, you must first understand the characteristics of the differential switch, and then proceed to its selection.
Key Features
So, among the most important technical characteristics that you need to rely on when choosing an RCD for an apartment and a private house, there are:
- Nominal voltage of the network: 220 V (single-phase) or 380 V (three-phase).
- Number of poles: bipolar (if 1 phase) and four-pole (if 3 phases).
- The rated load current can be 16A, 20A, 25A, 32A, 40A, 63A, 80A, 100A.
- Rated breaking differential current (leakage) 6 mA, 10 mA, 30 mA, 100 mA, 300 mA, 500 mA.
- Rated conditional short circuit current - varies from 3 kA to 15 kA. In simple words, this value shows the reliability of the RCD and its stability at short circuit. On the front panel, the value is displayed in a rectangle in amperes, or after the symbol “Inc”.
- Switching capacity (designation “Im”) - represents the maximum value at which the product is able to react normally. It should be not less than 10 values of the rated load, or not less than 500 A (modern products have a switching capacity from 1000 to 1500 A).
- Principle of operation: AC - operation at alternating current, A - variable + constant pulsating, B - constant + variable, S - there is a time delay before operation, G - there is also a delay, but its time is shorter.
- Design: electronic (works from a network) or electromechanical (does not demand food). What is the difference between electronic RCD and electromechanical, we told in a separate article.
We have provided the existing characteristics for you, now we will consider in detail how to take them into account in order to choose the right RCD in terms of power (in this case, amperage), leakage current and other parameters.
We recommend that you look at a selection of video tutorials in which the RCD calculation procedure is described in more detail, as well as the strategy for choosing the appropriate model using the example tables:
Right Criteria
Rated current
The first thing you need to pay attention to is what current the device is designed for. In order to choose the right RCD according to current, it is necessary to initially determine for what purpose the product will be installed. If you want to protect a separate network element, for example, a washing machine, an electric underfloor heating system or a water heater (boiler), the value can be no higher than 16 A. For all electrical wiring in the apartment, you must put the unit at least 32 A. To choose the right value, you first need to calculate the load from all connected electrical appliances and, starting from the amount received, choose the most suitable RCD model. On the case of modern technology, manufacturers usually indicate the rated current load, so there should be no difficulties with the calculations.
Differential current
We examined all the existing values, which range from 10 to 500 mA, now we will figure out which RCD is better to choose for amperage in certain situations. Protection of a person from electric shock is ensured by settings from 6 to 100 mA. At the same time, leaks above 30 mA will be felt by the human body. That is why it is better to choose a 10 mA model for a child’s and a bathroom, and 30 mA for protecting sockets and fixtures.
It should be noted immediately that each appliance has a natural leakage current, which is indicated in the attached technical data sheet. When choosing an RCD by leakage current, be sure to consider the following rule: the sum of natural leaks should not exceed the rated value of the protective device by more than 30% (1/3). Otherwise, false positives will occur, which causes a lot of trouble.
Product type
So, in simple words, we explain the purpose of each type of RCD:
- AC - It is mainly used to protect electrical appliances at home when using both single-phase and three-phase networks. Household appliances with pulsating current, for example, a washing machine, will not be able to protect such a product.
- AND - It is used just for separate protection of washing machines in apartments and private houses.
- B - mainly used in production, so choose this type for the home does not make sense.
- S - as we already said, the shutdown does not occur immediately when a leak is detected, but after a certain time setting. As a rule, it is used to prevent fire and is connected to the input panel, serving all the electrical wiring (therefore, the setting for the leakage current is selected at least 100 mA).
- G - basically connected to a separate electrical appliance for monitoring and timely fire protection. Unlike type “S”, it has a shorter holding time.
Design
There is nothing special to talk about, electronic ones have a more complex principle of operation and function only if there is a power source (external or mains). More reliable and durable - electromechanical, so it is better to choose an electromechanical RCD for an apartment and a house, in addition, the cost will be an order of magnitude lower.
Manufacturer
Well, the last, no less important criterion for choosing an RCD is by manufacturer. To date, the following companies are the best in the production of these products:
- Legrand;
- ABB;
- AEG;
- Schneider electric;
- Siemens
- DEKraft.
Among budget models, Austro-UZO and DEK have the highest quality.
We recommend giving preference to more expensive products, but if the budget does not allow, domestic manufacturers will also cope well with protection.In any case, before buying, we advise you to visit the forums on electrics and read customer reviews about the selected model! So you will surely learn all the advantages and disadvantages of the product and determine exactly which RCD is better to choose.
To summarize
So we provided recommendations on choosing a residual current device, now I would like to summarize and highlight those models that are used most often:
Private house (or cottage). At the input, a residual current circuit breaker with a rating of at least 100 mA for responding to leakage, type S and to a rated current of 63 A. Today, a three-phase network is often used, so the RCCB in this case should be four-pole. On separate groups: sockets, lamps, etc. It is recommended to install one RCD of type A (or AC) at 30 mA and rated current load according to calculations - 16/25 / 32A.
Flat. Everything is simpler here. Input shield - 32A, 30 mA device, type A / AC, usually bipolar (if not implemented replacement of wiring in the apartment to a new one). For a washing machine or a bathroom, you can choose another RCD separately at 16A.
This is all I wanted to tell you about this issue. We hope that now you know how to choose an RCD for an apartment and a house in terms of power, leakage current, and the manufacturer!
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I carefully re-read several sites on electrics, the conclusion is, in the bathroom, the ouzo or difavtomat should be at a leakage current of 10mA, but everywhere the power of the washing machine or hairdryer is considered up to 2.5 square meters. I want to install a flowing water heater with a capacity of 8 kW at home. Respectively, the current of the device is 36.4 A at 220 volts, with an increase in voltage above. The wire laid 6mm / sq; automatic shutdown at 40A at the entrance to the apartment. But it was not possible to find an RCD or a difavtomat with a leakage current of 10 mA. The question is what to do, you cannot go to a lower capacity of the water heater, because 8kW minimum power that will heat water in the winter to the required temperature. It is embarrassing that everywhere the focus is that the leakage current in the bathroom should be no more than 10 mA, on other devices outside the bathroom 30mA. Will a leakage current of 30 mA in a bathroom be safe? I would like to know your opinion on what I need to deliver. The line to the washing machine in the bathroom is separate.
Regards, Mikhail
Hello! Catalog number - MAD10-2-040-C-010 from IEK makes such devices.
Hello, tell me which is better to install the Van difavtomat on a boiler and a washing machine, on each device separately? Is it necessary to make a connection with grounding? There is no way to carry out grounding. Thanks
I did not read it carefully.
However, I did not understand what the author wrote about.
Either about ouzo, or about differential.
In the end, the article is relevant, but not about the topic of the topic.
if you are about the first lines where it says "differential current switch", then this is one of the names of the RCD. And what is called a "differential" is a "differential current switch with overcurrent protection" or AVDT, which stands for AUTOMATIC differential current switch.
Does it make a difference to install a machine before an RCD or after? - found such connection schemes on the network ...
Irrelevant. if you install an RCD before the group machine, it will still be UNDER the introductory one, and vice versa.
Hello! Everywhere the information that the RCD must be one rating higher than the AB that protects it. And if the RCD Hager 16A / 10mA, this manufacturer does not have 25A / 10 mA.If you put AB of the same rating of 16A, then the RCD will not be protected against short circuit. Putting AB 10A is not enough. How to be
But why is there an RCD protection from a short circuit? The nominal value is higher than the automatic machine RECOMMENDED to choose an RCD and it shouldn’t do anything ... If there is a short circuit, then the AB should disconnect, it protects not the RCD, but the wiring from the short circuit. No matter what his denomination is. A higher rating is recommended to extend the life of RCD contacts, such that they do not work to the limit of their capabilities.