Surely you know the most dangerous troubles regarding electrical wiring in the house: short circuits, network overloads, etc. It is precisely the latter trouble that is effectively protected by the device, also called a residual current switch (RCB). We will talk further about how to choose an RCD for an apartment and a house!
Importance of the event
If you choose the wrong RCD model, that is, make a mistake with its characteristics, this is fraught with the following consequences:
- The automation will be triggered during a false alarm, because... minor electrical leaks are always present in the wiring, especially if it is old (in a wooden house in the country).
- The overly high power rating of the RCD you choose will not operate during a dangerous situation, resulting in an electric shock.
- The device will not be able to function when connecting the aluminum conductors of your home wiring, since most modern models are designed only for connecting copper conductors.
To prevent these errors, you first need to understand the characteristics of the differential switch, and then proceed to its selection.
Main characteristics of the device
So, among the most important technical characteristics that you need to rely on when choosing an RCD for an apartment or private house are:
- Rated network voltage: 220 V (single-phase) or 380 V (three-phase).
- Number of poles: two-pole (if 1 phase) and four-pole (if 3 phases).
- The rated load current can be 16A, 20A, 25A, 32A, 40A, 63A, 80A, 100A.
- Rated residual 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 . On the front panel, the value is displayed in a rectangle in amperes, or after the “Inc” symbol.
- Switching capacity (designation “Im”) – represents the maximum value at which the product is able to react normally. Must be no less than 10 rated load values, or no less than 500 A (modern products have a switching capacity of 1000 to 1500 A).
- Operating principle: AC - operation with alternating current, A - alternating + constant pulsating, B - constant + alternating, S - there is a time delay before operation, G - there is also a delay, but its time is shorter.
- Design: electronic (works from the network) or electromechanical (does not require power). , we talked about in a separate article.
We have provided you with the existing characteristics, now we will consider in detail how they need to be taken into account in order to correctly select the RCD based on power (in this case, amperage), leakage current and other parameters.
Criteria for correct selection
Rated current
The first thing you need to pay attention to is what current the device is designed for. To choose the right RCD for current, you must first decide for what purpose the product will be installed. If you want to protect a separate network element, for example, a washing machine, an electric heated floor system or a water heater (boiler), the value can be no higher than 16 A. For all electrical wiring in the apartment, you need to install the unit at least 32 A. To select the correct value, you first need to calculate the load from all connected electrical appliances and, based on the resulting amount, select the most suitable RCD model. Manufacturers usually indicate the rated current load on the case of modern equipment, so calculations should not be difficult.
Differential current
We have considered all the existing values, which range from 10 to 500 mA, now we will figure out which RCD is better to choose based on amperage in certain situations. Protection of a person from electric shock is provided 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 children’s rooms and bathrooms, and 30 mA to protect sockets and lamps.
It should also be noted that each electrical appliance has a natural leakage current, which is indicated in the attached technical data sheet. When choosing an RCD based on leakage current, be sure to take into account the following rule: the sum of natural leakages should not exceed the rated value of the protective device by more than 30% (1/3). Otherwise, false positives will occur, which will cause a lot of trouble.
Product type
So, in simple words we explain the purpose of each type of RCD:
- AC– mainly used to protect electrical appliances at home when using both single-phase and three-phase networks. Such a product cannot protect household appliances with pulsating current, for example, a washing machine.
- A– used specifically for separate protection of washing machines in apartments and private houses.
- B– are mainly used in production, so there is no point in choosing this type for home.
- S– as we have already said, 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 at the input panel, servicing all electrical wiring (therefore, the setting for the leakage current is selected at least 100 mA).
- G– mainly connected to a separate electrical device for control and timely fire protection. Unlike the “S” type, it has a shorter exposure time.
Design
There is nothing special to talk about here; electronic ones have a more complex operating principle and function only if there is a power source (external or mains power). Electromechanical ones are more reliable and durable, so it is better to choose an electromechanical RCD for an apartment or house, and the cost will be much lower.
Manufacturer
Well, the last, no less important criterion for choosing an RCD is based on the manufacturer. Today, the best companies in the production of these products are the following companies:
- Legrand;
- Schneider electric;
- Siemens;
- DEKraft.
Among budget models, the highest quality is from the companies Austro-UZO and DEK.
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 purchasing, we advise you to visit electrical forums and read customer reviews about the chosen model! This way you will probably find out all the advantages and disadvantages of the product and determine exactly which RCD is better to choose.
Let's sum it up
Private house (or cottage). At the input there is a residual current device with a rating of at least 100 mA to respond to leakage, type S and a rated current of 63 A. Today, a three-phase network is often used, so the RCCB in this case must be four-pole. Into separate groups: sockets, lamps, etc. It is recommended to install one RCD of type A (or AC) at 30 mA and a rated current load according to calculations - 16/25/32A.
Apartment. Everything is simpler here. Input panel - 32A, 30 mA device, type A/AC, usually two-pole (if not installed on a new one). For a washing machine or bathroom, you can choose another RCD separately for 16A.
The residual current device prevents fire due to current leakage and eliminates the risk of electric shock. Therefore, many people are interested in installing this device. True, an RCD cannot be bought at random; its choice must be careful - taking into account the design, type and other criteria.
The importance of purchasing a quality RCD
An irresponsible approach to choosing a residual current device, that is, purchasing a device that does not suit the characteristics of a house or apartment, can cause certain problems:
- false alarms of the automation, since small electrical leaks are a natural situation for wiring that was installed a relatively long time ago;
- untimely receipt of information about a dangerous incident if an overly powerful RCD is selected, which can lead to electric shock;
- the inability of the RCD to function with existing wiring made of aluminum conductors, because almost all devices operate only on copper wires.
In order not to make a mistake when choosing an RCD, it does not hurt to carefully familiarize yourself with the device’s parameters before purchasing.
Table: main parameters of RCD
| RCD parameter | Letter designation | Description | Additional Information |
| Rated voltage | Un | The voltage level that is selected by the device manufacturer and is necessary for its operation. | Usually the rated voltage is 220 V, sometimes 380 V. Uniform voltage in the electrical network and the rated voltage of the residual current switch, as the RCD is also called, is an important condition for the trouble-free operation of the device. |
| Rated current | In | The highest current value at which the RCD operates for a long period. | The rated current value can be as follows: 10, 13, 16, 20, 25, 32, 40, 63, 80, 100 or 125 A. In relation to the differential circuit breaker, this value also acts as the rated current of the circuit breaker in the RCD configuration. For differential automatic machines, the rated current value is selected from the range: 6, 8, 10, 13, 16, 20, 25, 32, 40, 63, 80, 100, 125 A. |
| Rated residual current | Idn | Leakage current. | This characteristic of a residual current device is considered the main one, since it indicates what amount of differential current will cause the device to react. RCDs are produced with the following parameters of the rated residual current: 6, 10, 30, 100, 300 and 500 mA. |
| Rated conditional short-circuit current | Inc | An indicator by which one can judge the reliability, strength and quality of an RCD. | The rated conditional short-circuit current shows how well the electrical connections of the mechanism are made. The value of the rated short circuit current is standardized and can be equal to 3000, 4500, 6000 or 10000 A. |
| Rated differential short-circuit current | IDc | Another indicator of the quality and reliability of the device. | Similar to rated conditional short-circuit current. The only difference is that the overcurrent passes through one conductor of the residual current device, and testing of the operation of the device is carried out after turning on the test current in turn across different poles of the RCD. |
| Limit value of non-switching overcurrent | - | This is a characteristic that reflects the ability of the residual current switch to ignore symmetrical short circuit currents and situations where the network is overloaded. | This indicator has nothing to do with the current value at which the residual current device is required to block the power supply. The minimum non-switching current must correspond to the rated load current increased by 6 times. |
| Rated making and breaking (switching) capacity | Im | A parameter that depends on the degree of technical preparation of the RCD, that is, on the power of the spring drive, the raw materials used and the quality of the power contacts. | The switching capacity can be 500 A or 10 times the rated current level. For high-quality devices it is 1000 or 1500 A. |
| Rated making and breaking capacity for differential current | IDm | A characteristic that is also determined by the technical design of the residual current switch. | This parameter is comparable to the previous one (Im), but differs from it in that the flow of differential current is taken into account. It is often assessed during a short circuit to the housing of the electrical receiver in the TN-C-S system. |
Device parameters measurements
Before purchasing an RCD, you should determine the maximum current and leakage current. When making calculations, it is necessary to take into account that the network voltage on all wiring cores is usually 220 V.
To find a suitable overcurrent protective device, it is enough to determine what the maximum level of power consumption will be and divide its value by the voltage in the electrical network. In other words, the calculation is carried out according to the formula I = P/U. For example, if it is determined that the total household appliances in the apartment absorb 6000 W of electricity, then the maximum current value will be 27 A. In such a situation, it is better to choose a 32 A RCD, since this value is standardized and is as close as possible to 27 A.
A 32 Ampere RCD is suitable for equipment consuming 6 kW of electricity
The second characteristic - leakage current - is determined by a simple method. The dependence of various types of RCD on the individual characteristics of the apartment or house where it is necessary to install a differential current switch is taken into account.
Table: dependence of leakage current on the type of room
Criteria for selecting an RCD
When searching for a suitable protective shutdown, the first thing they look at is the rated and differential current indicators. After this, attention is focused on the type and design of the device, and they also find out which company produced the RCD.
Rated current
Craftsmen who specialize in working with electricity advise buying a residual current device with a rated current an order of magnitude higher than the calculated one. Thanks to this, it will be possible to achieve reliable operation of the differential current switch and not have to repair or replace it for a long time. For example, for a 40 A machine, it is more advisable to choose a 63 A RCD.
Leakage current
The rated differential breaking current of the RCD must be at least 3 times greater than the leakage current of the electrical circuit protected from accidents, i.e. the condition IDn> = 3*ID must be met.
The total leakage current of an electrical installation ID is determined by a special device or calculated using certain data. If it is not possible to carry out measurements, it is recommended to determine the leakage current at the rate of 0.4 mA per 1 A of load current, and the circuit leakage current at the rate of 10 μA per 1 m of phase conductor length.
Acceptable values of the rated breaking current can be found in a special table.
Table: dependence of the recommended value of RCD leakage current on the rated load current
Types of residual current devices
The residual current switch can be one of the following types:
Type B RCD is quite rare; on its body you can see an icon in the form of solid and dotted straight lines RCD design
If we consider the design of residual current devices, they are divided into the following types:
- electronic RCDs with a built-in board that instantly responds to any changes in the specified parameters and turns off the power from the network, but is not able to work without power supply from an external source;
- electromechanical RCDs, which are reliable because they do not require power and are easily triggered in response to the appearance of differential current.
Manufacturers of residual current devices
As electricians note, the most durable and reliable residual current devices are those produced under the following names:
Features of RCD operation
- in areas that should fundamentally be safe;
- in areas where power outages could cause moderate-hazard incidents.
When connecting an RCD, it is fundamentally important to insulate the neutral wire from grounding and the neutral wires of other similar devices In most cases, electricians accept the use of a grounded residual current device. The main thing is to connect it correctly. The RCD is triggered only when exposed to a leakage current that is higher than the standard value. And artificially created, like natural or home-made grounding, is distinguished by resistance, whose level does not allow a current with the required value to appear. It turns out that in this situation the RCD will not be able to operate.
Another option for incorrectly connecting an RCD is poor-quality insulation of the output neutral wire relative to the ground. If the neutral conductor is connected to the grounding circuit, the RCD will constantly generate false alarms.
Checking the functionality of the RCD
To make sure that the RCD performs its task, you can use the “Test” button located on the front panel of the device. When a button is pressed, an electrical circuit should be created inside the device, replicating the leakage situation.
If there is no shutdown, the following situations are possible:
- the device is not connected to the network correctly;
- the button is broken or its electrical circuit does not work;
- The device protection is faulty.
You can make sure that the reason the RCD does not operate is due to a broken button or protective mechanism using other methods.
Accurate results are shown by checking the residual current switch using a simple AA battery. The type A device operates regardless of the polarity of the battery connection. And an AC type device operates only with a certain polarity. This is explained by the fact that type A RCD reacts to any electric current.
Using a battery, you can accurately check whether the RCD is working A method that uses an incandescent lamp and a resistor allows you to simulate a real accident to evaluate the operation of the device. This method differs from testing with the “Test” button by creating a circuit for current leakage not inside, but outside the device.
To test an RCD in this way, you need to prepare:
- 10 W incandescent lamp;
- resistor 2.3–2.5 kOhm with a power of 5–10 W;
- lamp socket;
- insulated wire.
Testing using a lamp and resistor is carried out in stages:
If the protection works, the outlet will instantly disconnect from the network.
Video: RCD check
RCD and automatic
Since the residual current device is not equipped with its own “shield” that protects against short circuits and network overloads, an automatic circuit breaker must be installed along with it. The associated devices function in a special way: if a leak is detected, the RCD reacts to the situation, and when overcurrents appear, the machine is triggered.
The residual current switch must be protected from accidents by an automatic circuit breaker, the rating of which is equal to the rated current of the RCD. The installation location of the machine (before or after the protective device) does not play a special role. It is also not so important how many protective devices are connected to the RCD.
Connecting an RCD to several machines
As an example, consider a circuit consisting of two 25 A RCDs and a 40 A input circuit breaker, to which their own groups of circuit breakers are connected.
The residual current device must be protected by a circuit breaker having an equal or lower operating current rating In this case, two circuit breakers with a rating of 6 A and 16 A are additionally connected to the first device, and three circuit breakers with a rating of 16 A and one circuit breaker with a rating of 10 A are connected to the second device. The input circuit breaker cannot serve as a shield for the first RCD, since 40 A> 25 A. Therefore, additional machines with a nominal value of no more than 25 A are placed in front of it (6 A + 16 A = 22 A).
The second RCD (40 A) is connected to circuit breakers with a total rating of 58 A. They do not protect the RCD from too high a current, so it may fail before the input circuit breaker disconnects this section of the circuit from the voltage. Therefore, here it is recommended to replace the second RCD with a more powerful one, for example, rated 63 A, or protect the existing one with a separate 32 A circuit breaker installed one step higher than the machines being serviced.
In a private house, one RCD can be installed for lamps and sockets. In the apartment, in addition to the input panel, you should protect the washing machine from emergency situations by installing a 16 A RCD.
You need to think carefully and responsibly about which RCD to install in a private home. The device must have the necessary operating power and, in all technical parameters, correspond to the electrical system available in the room. How to correctly select a protection element that meets the requirements?
We'll tell you how to find a device that will function correctly for a long time. The selected model will protect your home from fire situations, protect equipment from burnout, and protect users from burns and electric shocks. A list of the best offers on the market will help you make your choice.
The abbreviation “UZO” stands for residual current device.
The unit is used for such important purposes as:
- differential protection of a person from electric shocks at the moment of touching a household electrical appliance that, due to various circumstances, is energized;
- protecting residential property from fire caused by low-quality insulation of in-house electrical wiring.
From a physical point of view, the basic function of the device is to protect the electrical network from high leakage currents by instantly and completely shutting down the system at the moment of recording indicators exceeding the maximum permissible standards.
Some parameters of RCDs built into instrument panels can be set using a practical and convenient multimeter or an indicator screwdriver
There are certain requirements for installing and using the module. You can learn about them clearly and in detail in the relevant documents, for example, in the latest editions of the PUE or in brochures describing the current series of standards for electrical installations of buildings IEC 60364 and the impact of electric current on people IEC 60479-1.
Design features of devices
The residual current device is not too complicated and consists of only four main working elements, such as:
- differential current transformer;
- a special mechanism responsible for breaking the connected circuit;
- electromagnetic type relay;
- test node.
Opposite windings - zero and phase - are connected to the transformer device. When the network operates in normal standard mode, conductors in the area of the transformer core control magnetic fluxes, which are initially in the opposite direction.
Based on the type of design, they are divided into electromechanical and electronic. Products of the first type are a simplified type of safety module, and are triggered immediately upon initial detection of a current leak, regardless of what voltage is currently available in the network.
The main working component of an electromechanical device is a toroidal core with windings. When a leak appears in the area of responsibility of the device, voltage appears in the secondary winding level to activate the relay. This process causes the mechanism to shut down the network
For correct operation, the device does not require an external power source. It has good operational stability, since it does not have any electronic parts in its design that can be damaged or burned when the network is overloaded or as a result of sudden power surges.
It is quite cheap and is sold in almost any store that sells an assortment for household needs or the construction of electrical networks. It works reliably and for a long time, without requiring complex additional maintenance.
An RCD that has been triggered to open the network cannot be turned on immediately. First you need to find the area of the problem and fix it. Only then is it permissible to return the device to working condition
The electronic type RCD is a more modern control module and is equipped with sensitive microcircuits that respond to any changes that occur in the network. It works even if the mains voltage drops, since the transformer element “notices” only the difference in current flow.
The main working element is an electronic board located inside with a special amplifier. For correct functioning, it certainly needs power supplied from an external network. If the system has a base voltage of 220 V, the protective device immediately reacts to the leak and opens.
Despite a more advanced design device, electronic protection devices are not always able to perform their functions. For example, when the neutral wire in the network burns out, they may not work
The electronic device is very sensitive and as a result of constant voltage fluctuations it can fail and lose its protective functions, and this will not be noticeable outwardly.
In order not to suffer due to this situation, experts strongly recommend that users monthly check the RCD for functionality by pressing the “Test” button located on the device body.
How does the protection device work?
The connection of the protective module to the main electrical system is always carried out after the input and electricity meter. A single-phase RCD, designed for a network with a standard rating of 220 V, has in its design 2 working terminals for zero and phase. Three-phase units are equipped with 4 terminals for 3 phases and a common zero.
While in activated mode, the RCD compares the parameters of incoming and outgoing currents, and calculates how many amperes go to all electrical consumers in the room. When working correctly, these indicators are no different from each other.
Sometimes an RCD can trip for no apparent reason. This situation is usually caused by sticky buttons and unbalanced devices caused by excessive operating load or condensation.
The difference between the input and output currents clearly indicates that there is an electrical leak in the house. Sometimes it occurs due to human contact with an exposed wire.
The RCD detects this situation and immediately de-energizes the controlled section of the network in order to protect the user from potential electric shock, burns and other household injuries associated with electricity.
The lowest threshold at which the residual current device is triggered is 30 mA. This indicator is called the non-release level, at which a person feels a sharp electric shock, but is still able to let go of an energized object.
At an alternating voltage of 220 V with a frequency of 50 Hz, a current of 30 milliamps is already felt very strongly and causes a convulsive contraction of the working muscles. At such a moment, the user is physically unable to unclench his fingers and throw aside a part or wire that is under high voltage.
All this leads to dangerous situations that threaten not only health, but also life. Only a properly selected and correctly installed RCD can prevent these troubles.
Classification according to operating principle
All protective devices offered today on the market of related electrical equipment and accessories differ from each other in the type of operation. AC modules are installed in systems designed to protect household appliances from surges or slowly rising voltages and are triggered by alternating current.
Products A detect a constant pulsating current that increases in steps and react precisely to it. They are usually installed in homes for individual protection against extremes and combustion of washing machines, televisions and dishwashers. They have a structurally complex structure and are much more expensive than other elements of this class.
The most suitable place to locate an RCD in a residential building is an area close to a power source. Experts recommend placing the device directly next to the common meter
Units B are not suitable for homes or other residential areas. Their area of operation is enterprises and production workshops with a large amount of electronic equipment.
Selective devices S and G are triggered 1-4 seconds after a leak is detected. They are usually implemented in networks where several protective devices are present on one power line.
Main parameters of product selection
It is necessary to select an RCD in strict accordance with the main operating indicators of the electrical system located in the house.
Too strong protection, far exceeding the power of all household appliances available to the owners, will not cope with the task in the future and will not be able to protect the user and home from fire hazards because it will not detect a dangerous leak.
It is better to purchase an RCD with a small margin. Otherwise, the appearance of any new household appliance module in the house will cause an overload and lead to the constant operation of the protective device
A device designed to operate at relatively small excesses simply cannot withstand a basic load. In addition, it will start to operate too often, thus causing a lot of inconvenience to the owners of the premises.
Selection by type of network voltage
Voltage 220 V is a classic indicator relevant for single-phase networks used to supply power to standard consumers. The normally permissible deviation from the indicator is within +/-5%.
According to these data, the voltage range of 209-231 V is considered optimal and does not put unnecessary stress on the system and the devices connected to it.
If several electrical branches come out of the distribution panel, you need to equip each of them with a separate RCD. This will entail additional costs, but if there are problems and the device is triggered on one line, everyone else will be able to continue working as usual
To protect such a network, usually laid in a small house, a simple RCD is used, designed to withstand minor voltage surges and work correctly with the circuit breakers already in the house.
The indicator should be an order of magnitude higher than the total total power of all household appliances available in residential premises.
In large houses with a large number of household appliances and the presence of specific electrical appliances that ensure the vital functions of the room, a more powerful and operationally stable three-phase 380 V network is often used.
A special protective device is used for it, slightly different in configuration from the standard single-phase one. The response threshold level of such a product is very high. It is placed in a special shield. are arranged in a certain order according to their purpose and selectivity rules.
The distributor, regardless of the number of floors of the building, is always located below in the area of the entrance to the house. As a rule, “S” protection is mounted on it with a certain delay time and a leakage current of 100 mA.
To avoid false alarms of the device, in some rooms where the wiring is outdated and has served its useful life, an RCD built into the socket is installed. Such a device monitors the level of current flow when activating household or lighting equipment and reduces the load on the system
Electrical lines across floors, living rooms, technical rooms, kitchens and bathrooms are laid from an input machine. In separate rooms where, according to fire safety requirements, the leakage current cannot exceed 30 mA, an individual single-phase protective unit is installed.
Number of poles for devices
The presence of a certain number of poles for safety devices is also an important selection criterion. Bipolar products are used only in single-phase networks where it is necessary to connect one working phase and zero.
If a single-phase network is equipped with a grounding system, then the RCD is installed according to the diagrams given in. It describes in detail the options and rules for connecting the protective equipment to phase, grounding and zero.
Located in ordinary electrical panels, RCDs with two poles occupy two seats according to the generally accepted DIN standard. For correct operation, a four-pole device requires 4 places
In three-phase systems with a base voltage of 380 W, units with four active poles are used, designed to activate zero and three phases.
Forward current level
The throughput or rated current of the RCD directly depends on the number and total power of devices and equipment connected to the electrical network.
In order for the input protective device to work correctly and not lose phase when the user simultaneously activates several units of household appliances, this indicator must be calculated for all energy-consuming modules available in the house.
The most common products used in everyday life are designated 16, 20, 25, 32, 40, 63, 80 and 100 amperes. For linear-type protective units, the operating power is calculated based on the number of electrical products connected to each individual branch
For ease of selection, manufacturers mark safety elements with numbers indicating the maximum throughput current in amperes.
Difference in leakage current
Leakage current is a certain value, upon reaching which the RCD opens the electrical circuit and stops powering the devices. This extreme threshold is called the rating and is usually 10, 30, 100, 300 and 500 Ma for different protective devices. How to install a selective RCD, you will learn from the contents of which we advise you to familiarize yourself with.
A 30 mA unit is considered optimal for small private houses. It copes well with the assigned task and turns off the line when a leak is detected that does not pose a danger to human life.
Products of a lower rating are overly sensitive and will deactivate the energy supply to devices with the slightest network fluctuation. There are others that a prudent owner should know about.
The best RCD manufacturers
The market for modern automatic equipment designed to monitor and control electrical systems is experiencing a period of active growth. Established manufacturers and promising newcomers are trying to offer the client the highest quality products with good functionality.
ABB Automatic Products
The Swiss-Swedish company ABB has confidently held the leading position in this segment for many years. Residual current devices manufactured at the company's production facilities are considered very reliable, durable and completely safe.
At the same time, in all respects they meet the latest requirements imposed in the EU for equipment and accessories of this kind.
ABB modules are more expensive than similar domestically produced devices. However, experts claim that all costs are completely justified, since RCDs of this brand are many times higher in all respects than similar devices of other brands
In the manufacture of its devices, the company uses innovative materials and parts with unsurpassed high operational stability. The range of models is very wide and satisfies the needs of electrical systems of any power and complexity.
What does IEK offer users?
IEK is a leading domestic manufacturer and supplier of lighting and electrical products. It has been successfully operating in the Russian and post-Soviet markets for more than 17 years. It creates a variety of high-quality equipment and provides an extended warranty for its products.
Residual current units from IEK are in great demand in Ukraine, Russia and Belarus due to the combination of optimal quality and affordable cost. The products are included in the line of budget products and allow you to equip the safety of your electrical system at a reasonable price.
IEK products sell very well due to the price, which is significantly lower than the cost of products from world brands
Each device fully complies with the declared characteristics and, when used correctly under the conditions described by the manufacturer, always performs for the prescribed period.
True, buyers sometimes complain that the devices have a weak plastic case that can crack or come apart if the clamping screws are tightened and often make a hum, even when there is very little load on them. But nevertheless, these disadvantages have practically no effect on IEK’s turnover, which only increases from year to year.
Nuances of products from the Kontaktor company
The Kontaktor plant is one of the largest-scale production facilities engaged in the manufacture of electrical products and related parts in Russia. Since 2007, it has been part of the group of companies that own the famous French brand Legrand. The concern specializes in the creation of lighting and electrical equipment.
Electricians and electricians speak very highly of the products of the Kontaktor plant and call them one of the highest quality, reliable and durable among products of budget Russian brands
The peculiarity of the plant’s products is that they are made in the same way as at Legrand’s European enterprises, and the cost does not exceed the price of similar domestically produced devices.
Classic installation solution
Of course, in each individual case, the RCD is selected taking into account the individual characteristics of the electrical system and the household appliances present in the living room. However, there is also a universal option suitable for most average homes.
All work on installing an RCD must be carried out with the electricity turned off and in strict compliance with basic safety regulations
In reality, the circuit looks like this: after the input circuit breaker, a 100 mA protection device is installed first. Outgoing lines that distribute current flow directly across floors and rooms are protected by more sensitive and sensitive devices with a reading of 30 mA.
On the line supplying electricity to devices located in rooms with high levels of humidity, for example, in a bathroom, bathroom or kitchen, a 10 mA protection device is placed with a rated current no less than the current of the circuit breaker mounted in front of the RCD itself.
You will find out how a residual current device differs from its “closest ally”, a differential circuit breaker, by reading. It examines in detail a difficult but very interesting topic.
Conclusions and useful video on the topic
What is an RCD, why is it needed and how to correctly install this device in a private home:
Rules for choosing RCDs for residential private houses based on differentiated current and length of electrical wiring. Detailed explanation of the process from a professional master:
Installing an RCD in a private home will not require significant material investments from the owners, but will increase the safety of the electrical system, protect residents from electric shocks and burns, and protect the property from fires.
For the device to work properly, it is better to choose a reliable product from a popular brand, rather than a Chinese nameless one. You won’t be able to save money here, but the result of the proprietary module will be many times higher than that of a cheap analogue.
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According to the PUE, residential properties must be connected to the power supply network through a residual current device (RCD). Any electrician will tell you that this device must be selected very carefully. How exactly to do this and why it is so important - this is what we will talk about now.
Why should an RCD be of high quality and reliable?
Types of RCD
The high demands placed on the RCD will seem quite justified if you understand the purpose of this device. It has only one function: to turn off the power supply if there is a current leak of a certain (threshold) value. A current leak is not fraught with harmless economic damage, as it might seem at first glance, but with much more serious consequences - it always indicates that one of the following situations is occurring:
- a person or animal has been struck by an electric shock;
- due to insulation damage, contact has appeared between a current-carrying element and some grounded metal structure, which can lead to a fire;
- the grounded body of any device or equipment is energized, as a result of which the user who touches it runs the risk of receiving an electric shock.
Thus, no less than the user’s life depends on whether the RCD works at the right moment. Therefore, you should never skimp on the quality of this device.
What you need to know about RCDs
The main element of the RCD is a differential transformer consisting of three coils. The first is connected to the phase, the second to the neutral conductor. In this case, the currents flowing through these coils generate magnetic fields with oppositely directed lines of force.
If the currents in the phase and neutral conductors are equal, then the geometric sum of the field lines will be equal to zero, that is, they will simply destroy each other. If the currents differ, then a residual field will form in the device, which will excite a current in the 3rd coil, and it, in turn, will force the shutdown relay to operate.
Note. The current that causes the RCD to trip is called differential current; accordingly, the RCD is also called a residual current switch.
Thus, to put it in simple language, the RCD compares the currents at the input and output of the circuit connected to it, and if “debit and credit do not match,” it blocks the supply of electricity. Two important conclusions can be drawn from this:
- The RCD does not protect against overcurrents (short circuit) or overloads, since in such situations the currents at the input and output of the circuit remain equal (there is no leakage). Thus, this device cannot be considered as an alternative to a fuse or circuit breaker - at least one of these devices must be installed at the entrance to the apartment or house. Instead of separate RCDs and circuit breakers, you can use a so-called differential circuit breaker, in which both of these devices are combined.
- The RCD will not turn off if a person touches the live element and the neutral wire at the same time. In this case, there will be an electric shock, but there will be no leakage - all the current will remain in the circuit.
Therefore, even with an RCD, one must not lose vigilance: live parts must be protected by casings, potentially dangerous places must be fenced off and marked with warning symbols and inscriptions.
Device characteristics
The most important characteristic of an RCD is the differential current setting, that is, the minimum value of the leakage current at which the device will disconnect the circuit. It is most often displayed in milliamps (mA) and can be 6, 10, 30, 100, 300 and 500 mA. This parameter is also called the sensitivity of the RCD: the lower it is, the more sensitive the switch is.
Another important characteristic is the response time of the device, that is, the duration of the period between the appearance of a leak and the shutdown of the RCD. Obviously, this period should be as short as possible, but there are special RCDs that are triggered with a time delay. They will be discussed below.
The third parameter is the rated current of the RCD, that is, the maximum current that the device can withstand without failure.
Calculation of RCD parameters
When calculating RCD parameters, manufacturers take into account the following data:
- A current of 50 mA is considered dangerous to humans. Therefore, all RCDs designed for protection against electric shock have a differential current setting of no more than 30 mA. Switches with a higher setting are fire protection.
- The response time is ensured so that in the event of an electric shock, fibrillation of the heart muscle does not occur. A period of 20–40 ms is considered safe in this regard.
- Each current strength corresponds to its own heat generation power. For example, with a current leak of 500 mA, 100 W of heat is generated. Based on this, the differential settings. current of fire-fighting RCDs does not exceed 500 mA.
The lower the ignition temperature of the building material of the building, the lower the leakage current setting of the fire protection RCD should be.
Criterias of choice
Now let's see how to select an RCD depending on its operating conditions.
Rated current
The rated current of the RCD must be one step higher than the circuit breaker installed in front of it. Thus, after a 16 A machine it is necessary to install an RCD with a rated current of 25 A, and after a 40 A machine - with a rated current of 50 A.
It would be a mistake to install an RCD with the same rated current as the machine: the circuit breaker, although triggered quickly, is still not instantaneous. So in the event of an overload, during its operation time, a current higher than the rated current will flow through the RCD. This time may be quite enough for it to fail.
Differential current (leakage)
Selecting the differential setting current, you should first of all take into account the amount of rated current flowing in the circuit. The point here is this: if you install an overly sensitive RCD at a high current, frequent false alarms will occur. Acceptable values of the leakage current setting for rated currents of different values are shown in the table:
However, as mentioned above, protection against electric shock can only be provided by an RCD with a leakage current setting of up to 30 mA inclusive. More precisely, for dry rooms - 30 mA, for rooms with high humidity (this includes bathrooms) - 10 mA.
To be able to install such RCDs, a section of the network with a large rated current is divided into several subsections (all consumers are divided into several groups) and each of them is equipped with its own differential switch. Current with sufficient sensitivity.
Let us draw the reader's attention to one exception: in networks with a “TT” type grounding system, it is mandatory to install an RCD with a leakage current setting of 30 mA, regardless of the rated current.
Note. Imported RCDs with a leakage current setting of 6 mA are produced to US standards - according to the requirements of local standards, the sensitivity of an RCD that provides protection against electric shock must be within the range of 4 - 6 mA.
Please also note that there are RCD models with an adjustable differential setting. Current, and it can be adjusted both discretely and smoothly.
Device type
RCDs are divided into several types according to two criteria. The first sign is a type of leakage current:
The second sign is the response time. Conventional RCDs, as mentioned, turn off 20 - 40 ms after the leak appears. But there are varieties that operate with a time delay:
These “inhibited” switches are installed to protect the usual ones. The connection is organized according to a cascade scheme: an RCD with a delay is installed on a common line, then the line branches into several groups and a regular RCD is installed on each of them. If a failure occurs with one of the conventional devices and it does not react to the leak, after a split second the common RCD will trip.
RCD design
According to their design, differential switches. Currents are divided into two types:
- Electromechanical. They consist only of a differential transformer (see above) and a shutdown relay.
- Electronic. Additionally, they include an electronic amplifier, which amplifies the current arising in the third (control) coil of the differential transformer in the presence of a leak. By equipping the RCD with an amplifier, the manufacturer has the opportunity to use a less powerful differential. Transformers and electronic switches are more compact and less expensive than electromechanical ones.
It would seem that the choice should definitely be made in favor of an electronic RCD. But you should know that not all of them are reliable enough. The point is this: an amplifier, like any electrical device, needs power and in the absence of it the switch cannot work. The power, of course, is taken from the circuit being serviced, that is, the RCD amplifier is connected to it at the very beginning in parallel with other loads.
Let us now imagine that the neutral wire breaks somewhere above the RCD (most often, the conductor is disconnected from the neutral bus). The integrity of the phase was not violated, therefore, all current-carrying elements remained energized, but the circuit was open, which means that all consumers, including the RCD amplifier, are inoperative. That is, the user will not be able to turn on any electrical appliance.
But if he touches, for example, a bare wire or a housing that has suffered a breakdown, he will receive an electric shock.
By the way, the likelihood that the user will touch a current-carrying element is quite high: seeing that the device is not working, 9 out of 10 citizens will think that this is happening precisely because of the lack of voltage, and will lose their vigilance.
So, in such a situation, if a person is struck by electric current, the electromechanical RCD will work, but the electronic one will not, since its amplifier will be inoperative due to lack of power. To increase the reliability of electronic RCDs, they began to be equipped with an additional disconnecting mechanism that is triggered when the amplifier's supply circuit is opened - this is the model you need to look for.
At the same time, it makes sense to find an option that “can” turn on automatically when the power is restored, otherwise the RCD will have to be turned on manually every time after a power outage.
We should also talk about how to recognize which RCD you are holding in your hands. There is no direct indication of its type in the form of the inscription “electronic” or “electromechanical”, and even sellers often cannot clarify the situation. Here's what to do:
- First of all, look at the diagram of the device shown on it itself. Electronic RCDs must have an amplifier in its composition - some kind of symbol to which power is supplied. In the vast majority of cases, the amplifier is indicated by a triangle. Nothing like this will be shown on the electromechanical RCD diagram.
- If, due to lack of experience, you are unsure about the correct interpretation of the circuit, pass a current through one of the poles of the RCD, connecting it to the most ordinary battery. Before this, of course, you need to remember to turn the device to the “on” position. If it turns off, then you have an electromechanical model. If not, reverse the polarity of the battery to allow current to flow in the opposite direction. If this time the switch does not work, then it is definitely electronic.
If there is a permanent magnet, bring it to the front panel of the RCD and move it slightly. The electromechanical switch will turn off during these manipulations, but the electronic switch will not.
Manufacturers
Today, the highest quality products are offered by manufacturers from Europe and the USA. First of all, these are companies:
- "ABB" (Sweden + Switzerland);
- Legrand, Schneider Electric (France);
- Moeller (German company, but recently acquired by Americans);
- General Electric (USA).
Of course, RCDs from these manufacturers are relatively expensive.
Devices from Siemens (Germany) are somewhat cheaper, but in terms of quality they are slightly inferior to RCDs from leading companies.
Products from domestic manufacturers may differ greatly, since some factories are owned by foreign investors. For example, a plant that produces RCDs under the Kontaktor brand is owned by the French company Legrand. This determines both the quality - it is much higher than that of many other domestic brands, and the price - it is comparable to the cost of a European-made RCD.
The following settled in the middle class:
- Kursk plant "KEAZ";
- DEKraft company.
The latter is notable for the fact that there are almost no negative reviews of its products online.
But IEK devices, on the contrary, are criticized quite often. Users report that they hum even under moderate loads and have a flimsy body that is easily deformed when the clamping screws are tightened. However, IEK brand equipment is quite popular because it has a very attractive price.
Devices from the well-known Chinese manufacturer EKF Electrotechnica can be included in the same category as the products of the IEK brand, both in price and in quality. But at the same time, the “Chinese” have a fairly long warranty period, for example, for circuit breakers it is 5 years. For comparison, the warranty for similar products from the KEAZ plant is 2 years.
Let us remind the reader once again that the quality of the RCD is often a matter of life and death, so it is not worth purchasing switches from dubious and little-known manufacturers for the sake of saving money. We should also not forget that products from well-known brands are actively counterfeited, so it is better to purchase RCDs in large stores that work directly with the manufacturer, or from official dealers.
Rated voltage
When choosing an RCD, be sure to look at whether it is 1-phase or 3-phase. In the first case, the rated voltage of 230 V will be marked on the case, in the second - 400 V.
Installation method
It is useful to know that, along with stationary RCDs intended for installation in a switchboard on a DIN rail, portable RCDs are produced. They are similar to a regular extension cord - they are plugged into an outlet and at the same time they themselves have several outlets for connecting electrical appliances.
It should be taken into account that the cost of such switches is significantly higher than that of stationary models.
Functionality check
All modern RCDs have a button labeled “TEST” (test). When you press it, current is supplied to a special test wire, as a result of which the RCD, if it is operational, should turn off. But there are two important points to consider:
TEST button
- Turning off the RCD when you press the “TEST” button only indicates the integrity of the internal circuits, but this fact does not guarantee that the characteristics of the device (breaking leakage current and response time) comply with regulatory requirements. Therefore, do not lose your vigilance and if you purchase an RCD in a small store or market, ask to see the certificate.
- In the same way, the operation of a switch that has already been installed in place when this button is pressed does not mean that it is connected correctly. It is likely that when the “TEST” button is pressed, the device will turn off, and will ignore the real current leakage due to a connection error.
If you want to truly test the performance of the RCD, you need to invite a professional electrician and ask him to perform a current leak test. We specifically draw the reader’s attention to the fact that this operation should be performed by a specialist.
Features of operation: Once a month, it is recommended to check the RCD using the " buttonTEST".
Connecting RCDs and circuit breakers
If electrical consumers in a house or apartment are divided into several groups, each of which is protected by its own circuit breaker, then in order to save money, you can install one RCD for 2 - 3 such groups. Today, it is possible to organize a connection in this way in almost any household network: among modern RCDs with a differential setting. current 30 mA, there are models designed for fairly high rated currents - up to 100 A.
When selecting an RCD for a group of machines, you should take into account the rated current of not only the higher-level machine, but also the lower ones. Let's explain with examples.
Example 1
Scheme for example 1
Let us recall that in the general case it is recommended to install an RCD with a rated current that is one step higher than the rated current above the installed circuit breaker. But in this case, as you can see, each of the two RCDs does not exceed the rated current, but, on the contrary, is inferior to the input circuit breaker: its rated current is 50 A, while the rated current of each of the RCDs is only 40 A.
However, the diff switches current are reliably protected from overload: the total rated current of the machines connected to each of them is only 32 A (2x16 A), which is 20% less than the rated current of the RCD of 40 A.
Example 2
The following scheme is not so reliable:
Scheme for example 2
The rated current of the 1st RCD is 25 A and the input circuit breaker with a rated current of 40 A does not protect it. But there is no risk of overloading this device, since the current passing through it cannot exceed 22 A (6 and 16 A circuit breakers are connected to the RCD). But the 2nd RCD, designed for a rated current of 40 A, can burn out: it is not protected by the circuit breakers connected to it, since their total rated current is 58 A (3x16 + 10), and the input circuit breaker is protected, so to speak, end-to-end .
If there is an overload, then before the input circuit breaker is triggered, a current higher than the rated one will flow through RCD No. 2, as a result of which it may fail. It is recommended to either install an RCD with a higher rated current (the next level is 50 A), or protect it with an additional circuit breaker with a rated current one step lower (32 A).
Example 3
But this scheme is clearly incorrect:
Scheme for example 3
Both RCDs with a rated current of 40 A are not protected by either the upstream circuit breaker (50 A) or the downstream ones (total rated currents are 57 and 48 A).
The optimal option for connecting an RCD
If there are several RCDs with their own group of circuit breakers, then it is very important not to mix wires from different groups. It is better to provide each group with its own zero bus - when all consumers are connected to a common zero bus, false alarms of the RCD are possible. The connection with individual buses is shown in the following diagram. Also shown here is the connection of a selective RCD.
RCD connection diagram
Red indicates phase (L), blue indicates neutral conductor (N), yellow-green indicates ground (PE).
As you can see, a selective RCD with a leakage current setting of 300 mA (position 3) protects RCDs 7 and 14 with a leakage current setting of 30 mA and at the same time protects the lighting circuits (circuit breakers positions 5, 6, 12). Protect the lighting wiring of the RCD with the differential setting. a current of 30 mA does not make sense, since here the probability of electric shock is practically zero.
It is understood that the differential machine 13 serves a dedicated line intended for connecting, for example, a computer or a washing machine, so the neutral conductor from it is routed directly to the load, and not to the neutral bus.
Additional zero buses are indicated by pos. 11 and 18. Groups of sockets 2, 3, 4 are connected to the first and a wire is laid from it to RCD 7; to the second - groups of sockets 5, 6, 7, the bus itself is connected to RCD 14.
Note that this circuit has the same drawback as that shown in example No. 2: the rated current of the input circuit breaker (item 1) is the same as the RCD pos. 7 and 14 - 40 A, while the total rated current circuit breakers connected to each of these RCDs is 3x16 = 48 A. For greater reliability, an RCD designed for a higher rated current should be installed.
When connecting an RCD to a group of machines, identifying the location of the leak is quite simple. For example, the RCD, pos. 7. It is necessary to turn off the automatic machines pos. 8, 9 and 10, then turn on the RCD and turn on the mentioned machines one by one. As soon as the circuit breaker with a leak is turned on, the RCD will immediately turn off.
Whether it will be able to save your life in the event of an emergency depends on whether you have chosen and installed the RCD correctly. Therefore, this issue should be approached with all due care. The recommendations outlined in our article will help you avoid mistakes that could be fatal.
How does an RCD work, where is it placed and why is it needed? If you find out the answers to these questions, your apartment or house will become more secure and safe to live in. After all, a residual current device (RCD) protects the home from fires in the wiring and the resulting troubles. Therefore, every prudent homeowner should become familiar with the design, installation method and calculation of its ratings.
RCD - what is it and how does it work
When deciphering the abbreviation RCD in electrical engineering, we mean a special unit that opens the circuit in the event of an emergency situation in the system. This situation primarily refers to a current leak in an apartment or house caused by a person who touched a bare wire or contact. In this case, the body will be used as a conductor through which the current will flow to the conditional ground, and a power surge will be recorded in the electrical network, measured in thousandths of an ampere (mA).
Conventional automatic fuses do not respond to such surges. They open the circuit only after detecting a current imbalance of 1 to 4 amperes (above the rated value). Only an RCD can save a person from a bare wire - a more sensitive breaker that responds to 10-30 mA. It is he who opens the circuit before the careless user has time to be afraid of the “bite” of the current. As a result, thanks to such a breaker, after contact with a bare wire, we are left with only unpleasant memories, and not serious injury or disability.
In addition, the RCD reacts to dangerous heating of the electrical wiring, which can be caused by either a short circuit or a jump in current characteristics caused by a fault on the line. The device also protects the network from connecting electrical appliances with excessively high power, which heat the wiring to boiler temperature, which is why in electrical engineering it is customary to use a special term - fire protection RCD.
Typical types of devices - 3 classifications
Why you need an RCD in an apartment or house, we have already figured it out. Now we should study the standard types of such interrupters. In this case, we will use three classification methods: by poles, by design features and by functional features. The first classification method involves dividing the product range of such devices into 2-pole and 4-pole groups. The module from the first group is installed exclusively in single-phase (household) electrical networks. Devices from the second group are installed on a three-phase (industrial) power supply network.
When choosing an RCD based on design features, we are dealing with two groups - electromechanical and electronic. The first includes non-volatile breakers that continue to operate even after the zero line in the wiring is broken. The second group includes volatile breakers that require constant power, since their main component is not a differential transformer, but an electronic board.
The third method - classification by functionality - distinguishes several types of breakers: AC, A B, F, G. The AC type is focused on sinusoidal current and increasing loads, and for such a device to work, both a sharp jump and a smooth increase in characteristics are enough. Type A responds to pulsating direct and alternating current, and loads can increase either gradually or intermittently. Type B is a classic industrial circuit breaker, and you most likely will not see it in an apartment, and F and G are fire protection RCDs used both in everyday life and in production.
Of course, the complete classification of breakers is not limited to the above methods, and in each case there will be a little more groups than we indicated, but the options mentioned are quite enough to understand which breakers should be used in an apartment or other residential premises.
How many and what kind of RCDs do you need for your apartment or house?
Before choosing an RCD for an apartment or house, we need to assess the needs and expectations of the home owner who needs such protection. So, with the help of such a breaker we want to protect ourselves from the following troubles:
- electric shock to household members;
- fire in the wiring, socket or electrical appliance itself;
- failure of expensive household appliances;
- short circuit or breakdown in a damp room (in the bathroom, for example).
At the same time, we need to select an RCD with the level of sensitivity we need so that such a device does not respond to “false calls” caused by electrical wiring. As a result, in a city apartment the following application scheme is practiced: a fire protection RCD on the central line, a separate breaker for the kitchen, a separate module for the bathroom and another device for all other rooms (corridor, living room, bedroom). Moreover, it is considered good form to use separate RCDs for water heaters and washing machines.
All apartment blocks are of the 2-pole variety and AC type. The only exception may be a block designed to fight fire - it is a G-type. In a private house, a slightly different scheme is practiced: a fire protection RCD on the central line and breakers for each branch supplying individual rooms. That is, the number of standard security modules should be equal to the number of rooms or functional areas in the home. Plus here you need to add separate RCDs for boilers and pumping stations.
"Home" devices can be either 2-pole or 4-pole types, depending on the number of phases in the home's power supply line. The fire protection RCD will be of F or G type, and the remaining modules will be of AC type. At the same time, for a private house it is better to choose a non-volatile version of the breaker - an electromechanical RCD.
How to calculate the parameters of a specific breaker
So, we have decided on the number of breakers and their layout, but the choice of RCD for a house or apartment does not end there. Before purchasing specific models, we need to calculate their characteristics. Without this, the module will operate on its own, annoying the owner of a private house or apartment. To calculate the RCD as accurately as possible, electrical network designers use parameters such as the power of electrical appliances connected to the line, the amount of leakage current, and even the length of the wiring.
For example, calculating a breaker for a room with a total energy consumption of 5 kW, connected to a 220-volt meter with an 11-meter-long wire, begins with determining the maximum current consumption, in this case it is 22.7 A (5000/220). Next comes the determination of the leakage current in wires and electrical appliances - this is about 11 and 9 mA (phase current minus neutral current), after which we select from the model range of RCDs with parameters closest to these values - 22.7 A and 20 mA. This will be a 25A/20mA machine, and before calculating the final parameters, all values must be increased by at least 30 percent. As a result, we will have to install a 32A/30mA breaker on the service line of such a room. That's all, now you know which RCD to choose in this case.
If long calculations bore you, instead of making an exact calculation, you can use the standard recommendations for breaker characteristics, which are as follows:
- The fire module requires parameters at the level of 62A/300 mA.
- A 16A/10 mA module is suitable for the bathroom and nursery.
- In rooms without energy-intensive electrical appliances (refrigerator, washing machine or dishwasher), you can install a 25A/30mA unit.
- It is better to install a 40A/30 mA breaker on the power line of a boiler or kitchen (or other energy-intensive room).
If you remember this data, you will not need to make complex calculations and select RCDs based on power and other parameters. And don’t let the high current values scare you - at 40 amperes the unit does not disconnect from the network (like a machine), but completely melts. And 30 mA of differential current, at which, will not scare even a teenager.
How to install the device - example with a boiler
Technically, it is very easy to install an RCD - strip the contacts of insulation and secure them with clamping screws.
Let's look at an example of connecting a breaker to a Termex boiler:
- We test the wiring contacts and find the line and neutral.
- We insert the neutral into the RCD socket marked with the letter “N”.
- We insert the line into the free socket on the same side. At the same time, in order for the breaker to start working, the connection to the network can be made both from the top and from the bottom of the unit body.
- We connect the free contacts in the RCD body with the corresponding connectors of the boiler.
Ready! Now the electrical appliance will work under protection. Just don’t forget to test the RCD at least once a month. To do this, just press the "Test" button on the case. And if the breaker opens the circuit, then it is fully operational.
