Selection of circuit breakers. Current characteristics of circuit breakers Rated currents of circuit breakers over 100

To control electrical wiring in an apartment or house, special protective devices are used that turn off the electricity when the network is overloaded. Characteristics such as load current and network voltage determine the ratings of circuit breakers.

Types of devices

There are several types of devices that can monitor wiring and, if necessary, cut off electrical power. They are:

1. Miniature (mini-models);
2. Air (open version);
3. Enclosed molded case switches;
4. RCD (Residual Current Devices);
5. Automatic switches additionally equipped with RCD (differential).

Miniature devices are designed to work in networks with light loads; as a rule, they do not have additional adjustment functions. This model range is represented by circuit breakers with a breaking capacity designed for a misfire current from 4.5 to 15 kA. Therefore, they are used most often in household wiring, since higher current strength is required for production capacities.

Models produced by Schneider Electric are very popular. There are machines on sale with ratings from 2 to 125 A, which allows you to select a separate device even for a small group of devices, for example, for connecting lighting or other electrical equipment (sconce, electric kettle, etc.).

If devices with a higher rating are required, say, to control the operation of electrical networks to which powerful consumers are connected, air-type circuit breakers are selected. Their cutoff current rating is an order of magnitude higher than that of miniature models. As a rule, they are produced in a three-pole design, but now many companies, including IEK, produce four-pole models.

Installation of automatic switches is carried out in a special cabinet where DIN rails are installed for their fastening. Distribution cabinets with the appropriate protection class (at least IP55) can be placed in open space (poles, street switchboards, etc.). The waterproof housing, made of refractory materials, ensures the proper level of safety.

The model line of these circuit breakers allows a slight deviation (up to 10%) from the specified characteristics. The biggest advantage of these machines over miniature ones is the ability to customize the operating parameters of the device.

For this purpose, special inserts are used, with which you can control the current strength at the contacts. In other words, when installing a calibrated insert on the active contact, it becomes possible to change the parameters of the switch, which in some conditions makes it possible to expand the nominal characteristics. Regardless of the range of action and ratings, circuit breakers have the same size across the entire model range, the only dimension that changes is the width (modularity). It depends on the number of poles (there can be 2 or more).

Automatic switches are mounted in a vertical position, with the exception of devices designed over 5000 A and 6300 A. They can be used for installation in open areas or in special switchboards. The advantage of such devices is the presence of additional contacts and connections, which significantly expands the scope of use and installation possibilities.

Enclosed circuit breakers are manufactured in a cast housing made of refractory material. This makes them completely sealed and suitable for use in extreme conditions. On average, the range of such machines is used with a current of up to 200 Amperes and a voltage of up to 750 Volts. Based on their operating principle, they are divided into the following types:

1. Adjustable;
2. Thermal;
3. Electromagnetic.

Depending on the needs, you need to choose the optimal operating principle of the devices. Electromagnetic type devices are considered the most accurate, since they determine the rms value of active currents and are triggered in the event of a short circuit. This allows you to prevent all negative consequences in advance.

Any of the listed types of devices can be manufactured in one of four standard sizes, with a cut-off current in the range from 25 to 150 A. The design can be two, three and four poles, which allows them to be used when connecting to the power supply network of both residential and production premises.

Electromagnetic machines have proven themselves to be excellent devices that can control the operation of the motors of machine tools or other equipment. A distinctive feature is the ability to withstand current impulses of up to 70,000 Amperes. The rated operating current is indicated on the device body.

RCDs cannot be considered independent devices for protecting networks from overvoltage. It is recommended to use them either in tandem with automatic machines, or immediately buy a switch equipped with an additional protection device (differential automatic devices). At the same time, during installation of wiring, the RCD is installed in front of the machines, and not vice versa. Otherwise, the device may simply burn out due to high short-circuit current pulses.

Video: load switches

Machine denominations (calculation according to the table)

To select the correct ratings for home and industrial circuit breakers, a special table is used:

Calculating the ratings of circuit breakers is also very simple. You need to select a group of devices, for example, it will be a kettle, a lamp, a refrigerator, after which you need to find out their power to determine the rated current. Let's use Ohm's law: I=P/U, Where:

• I – current consumed by the equipment (A);
• P – equipment power (W);
• U – mains voltage (V).

For example, we have a kettle with a power of 1.5 kW (1500 W), a lamp - 100 W, a refrigerator - 300 W; in total, the total value will be 1.9 kW (1900 W), we calculate the rated current: I = 1900/220 = 8.6. The closest automatic device in terms of operating current is 10 A. Naturally, in practice this figure will be higher; modern wiring must be designed for a load current of at least 16 A.

A slight overestimation of the parameters will not cause harm, but an underestimation may result in a short circuit and fire. Experts recommend that when there are a large number of amperes, use not one powerful machine, but several with an average rating - this ensures greater operational reliability.

The main characteristic of automatic protective equipment is the rated currents of the circuit breakers. This parameter is displayed on the device body along with the manufacturer's trademark and serial number. This value represents the maximum. The time for this current to flow through the circuit breaker can be infinitely long, without disconnecting the protected circuit. If the nominal value is exceeded, the machine is triggered and the protected circuit is opened.

Machine parameters

The main current ratings are standardized and represent the following range of values: 6, 10, 16, 20, 25, 32, 40, 50, 63, 80 and 100 amperes. These values ​​correspond exactly to their value when the temperature surrounding the machines does not exceed 30 degrees. If the temperature increases, the corresponding rated current will decrease.

This can happen when several devices are installed in an electrical panel at a very close distance from each other. Mutual heating occurs, as a result of which the value of the switched electric current decreases. In order to take this error into account, special correction factors can be used.

When several consumers are connected to the network at once, inrush currents may arise for a short time, many times exceeding the rated current of the circuit breaker. To avoid spontaneous shutdowns at such moments, it is practiced to use automatic machines with different time-current characteristics.

Time-current characteristic

When considering the rated currents of automatic machines, we must not forget about the time-current characteristic of their operation. Here the time of switching off the circuit and the strength of the current flowing through it depend. The actual flowing electric current is correlated with the nominal current and shows how many times it exceeds it. That is, with the same current, shutdown can occur in different ways.

There are several types of circuit breakers, depending on the time-current characteristics. Each type shows how many times it exceeds the current value. The scope of application of this or that type of circuit breaker also depends on this.

In some device models there is a C marking, meaning the ability to release as quickly as possible. This characteristic of the machines is a graph where the rated current is indicated horizontally, and the operating time of the device is indicated vertically.

Selecting a circuit breaker

To protect electrical circuits, various safety devices are used - RCDs, AVs, differential circuit breakers - which are largely similar in their purpose and operating principle. Some are a “set” consisting of several devices placed in one housing.

But they are all united by a common feature - protecting lines and connected equipment from current “surprises”, more precisely, exceeding the calculated value of a given parameter for a specific “thread” or the entire circuit. In this article we will look at the existing current ratings of circuit breakers.

People who do not understand the true purpose of the AV and the meaning of current protection are often guided by the principle “more is better” (in this case, the setting value is implied). This approach can lead to the fact that, figuratively speaking, everything around will melt and ignite, but it will not work. That is why for each circuit, AB is selected individually, after determining its parameters.

Calculation of the rated current value

What is taken into account:

• Voltage (V). In everyday life it is mainly 220/50.
• Total line load (W). It is determined by adding the powers of all connected devices (devices).

AB denominations

All current values ​​are in A.

1. Non-tunable AB. These are the simplest machines, installed mainly on individual threads. Their denominations are set by the manufacturer - 6, 10 and 16.
2. Adjustable AV. With rare exceptions, you can change the current in them by selecting the required value. AB denominations are 20, 25, 32, 40, 50, 63, 80 and 100.

When choosing a circuit breaker, you should read its data sheet. It indicates, in addition to the main characteristics, a correction factor. It is important if the device may overheat. For example, installation in rooms with high temperatures, dense layout of the power panel, and so on.

When assembling an electrical panel or connecting new large household appliances, the home master will certainly encounter such a problem as the need to select circuit breakers. They provide electrical and fire safety, so choosing the right machine is the key to the safety of you, your family and your property.

What is the machine used for?

A machine is installed in the power supply circuit to prevent overheating of the wiring. Any wiring is designed to carry a certain current. If the current passed exceeds this value, the conductor begins to heat up too much. If this situation persists for a sufficient period of time, the wiring begins to melt, resulting in a short circuit. A circuit breaker is installed to prevent this situation.

The second task of the circuit breaker is to turn off the power when a short circuit current (SC) occurs. When a short circuit occurs, the currents in the circuit increase many times and can reach thousands of amperes. To prevent them from destroying the wiring and damaging the equipment included in the line, the circuit breaker must turn off the power as quickly as possible - as soon as the current exceeds a certain limit.

In order for the protective circuit breaker to properly perform its functions, it is necessary to correctly select the machine according to all parameters. There are not many of them - only three, but you need to deal with each one.

What types of circuit breakers are there?

To protect conductors of a single-phase 220 V network, there are single-pole and double-pole disconnecting devices. To single-pole wires, only one conductor is connected - phase, to double-pole wires, both phase and neutral. Single-pole circuit breakers are installed on 220 V indoor lighting circuits, on socket groups in rooms with normal operating conditions. They are also installed on some types of load in three-phase networks, connecting one of the phases.

For three-phase networks (380 V) there are three and four poles. These circuit breakers (the correct name is a circuit breaker) are installed on a three-phase load (ovens, hobs and other equipment that operate on a 380 V network).

In rooms with high humidity (bathroom, bathhouse, swimming pool, etc.) two-pole circuit breakers are installed. They are also recommended for installation on powerful appliances - washing machines, dishwashers, boilers, ovens, etc.

It’s just that in emergency situations - in the event of a short circuit or insulation breakdown - phase voltage can reach the neutral wire. If a single-pole device is installed on the power line, it will disconnect the phase wire, and the zero with dangerous voltage will remain connected. This means there is still a possibility of electric shock when touched. That is, the choice of machine is simple - single-pole switches are installed on some lines, and double-pole switches on others. The specific amount depends on the network condition.

For a three-phase network, there are three-pole circuit breakers. Such a machine is installed at the entrance and at consumers, to which all three phases are supplied - an electric stove, a three-phase hob, an oven, etc. The remaining consumers are equipped with two-pole circuit breakers. They must disconnect both phase and neutral.

Example of three-phase network wiring - types of circuit breakers

The choice of circuit breaker rating does not depend on the number of wires connected to it.

Deciding on the denomination

Actually, from the functions of the circuit breaker, the rule for determining the rating of the circuit breaker follows: it must operate until the current exceeds the capabilities of the wiring. This means that the current rating of the machine must be less than the maximum current that the wiring can withstand.

Based on this, the algorithm for selecting a circuit breaker is simple:

• for a specific area.
• See what maximum current this cable can withstand (see the table).
• Next, from all the ratings of the circuit breakers, we select the nearest smaller one. The ratings of the machines are tied to the permissible long-term load currents for a particular cable - they have a slightly lower rating (see the table). The list of denominations looks like this: 16 A, 25 A, 32 A, 40 A, 63 A. From this list you choose the appropriate one. There are smaller values, but they are practically not used anymore - we have too many electrical appliances and they have considerable power.

Example

The algorithm is very simple, but it works flawlessly. To make it clearer, let's look at an example. Below is a table that shows the maximum permissible current for conductors that are used at. Recommendations regarding the use of machines are also given there. They are given in the column “Nominal current of the circuit breaker”. This is where we look for the ratings - it is slightly less than the maximum permissible for the wiring to work normally.

In the table we find the selected wire cross-section for this line. Suppose we need to lay a cable with a cross-section of 2.5 mm 2 (the most common when laying to medium-power devices). A conductor with this cross-section can withstand a current of 27 A, and the recommended rating of the machine is 16 A.

How will the circuit work then? As long as the current does not exceed 25 A, the machine does not turn off, everything works as normal - the conductor heats up, but not to critical values. When the load current begins to increase and exceeds 25 A, the machine does not turn off for some time - perhaps these are starting currents and they are short-lived. It turns off if the current exceeds 25 A by 13% for a sufficiently long time. In this case, if it reaches 28.25 A. Then the power supply will work and de-energize the branch, since this current already poses a threat to the conductor and its insulation.

Power calculation

Is it possible to choose a machine based on load power? If only one device is connected to the power line (usually large household appliances with high power consumption), then it is permissible to make a calculation based on the power of this equipment. You can also choose an introductory machine based on power, which is installed at the entrance to a house or apartment.

If we are looking for the rating of the input circuit breaker, we need to add up the power of all devices that will be connected to the home network. Then the found total power is substituted into the formula, and the operating current for this load is found.

After we have found the current, select the nominal value. It may be either slightly more or slightly less than the found value. The main thing is that its shutdown current does not exceed the maximum permissible current for this wiring.

When can you use this method? If the wiring is laid with a large margin (this is not bad, by the way). Then, in order to save money, you can automatically install switches that correspond to the load, and not the cross-section of the conductors. But once again we draw your attention to the fact that the long-term permissible current for the load must be greater than the maximum current of the circuit breaker. Only then will the choice of circuit breaker be correct.

Selecting the breaking capacity

The selection of a packager based on the maximum permissible load current is described above. But the network circuit breaker must also turn off when a short circuit (short circuit) occurs in the network. This characteristic is called breaking capacity. It is displayed in thousands of amperes - this is the order currents can reach during a short circuit. Selecting a machine based on its breaking capacity is not very difficult.

This characteristic shows at what maximum value of the short-circuit current the circuit breaker remains operational, that is, it will not only be able to turn off, but will also work after being turned on again. This characteristic depends on many factors and for accurate selection it is necessary to determine the short-circuit currents. But for wiring in a house or apartment, such calculations are done very rarely, and are based on the distance from the transformer substation.

If the substation is located close to the entrance to your house/apartment, take a circuit breaker with a breaking capacity of 10,000 A; for all other city apartments, 6,000 A is enough. If the house is located in a rural area or you are choosing a circuit breaker for a summer residence, it may well be enough and a breaking capacity of 4,500 A. The networks here are usually old and the short-circuit currents are not large. And since the price increases significantly with increasing breaking capacity, the principle of reasonable savings can be applied.

Is it possible to install bags with a lower breaking capacity in city apartments? In principle, it is possible, but no one guarantees that after the first short circuit you will not have to change it. He may have time to turn off the network, but will be inoperative. In the worst case scenario, the contacts will melt and the machine will not have time to turn off. Then the wiring will melt and a fire may occur.

Type of electromagnetic release

The machine must operate when the current rises above a certain level. But short-term overloads periodically occur in the network. They are usually associated with inrush currents. For example, such overloads can be observed when turning on the refrigerator compressor, washing machine motor, etc. The circuit breaker should not turn off during such temporary and short-term overloads, because they have a certain delay for operation.

But if the current has increased not because of an overload but because of a short circuit, then during the time that the circuit breaker “wait”, its contacts will melt. This is what an electromagnetic automatic release is for. It operates at a certain current value, which can no longer be an overload. This indicator is also called cut-off current, since in this case the circuit breaker cuts off the line from the power supply. The magnitude of the operating current can be different and is displayed in letters that appear in front of the numbers indicating the rating of the machine.

There are three most popular types:

What characteristics should you choose? In this case, the choice of a circuit breaker is also based on the distance of your household from the substation and the state of the electrical networks; the choice of a circuit breaker is carried out using simple rules:

• With the letter “B” on the body they are suitable for dachas, houses in villages and towns that receive power supply through air ducts. They can also be installed in apartments of old houses in which the internal electrical network has not been reconstructed. These circuit breakers are not always on sale; they cost a little more than category C, but can be delivered to order.
• Bags with a “C” on the body are the most widely used option. They are installed in networks with normal condition, suitable for apartments in new buildings or after major renovations, in private houses near the substation.
• Class D is installed in enterprises and workshops with equipment with high starting currents.

That is, in essence, the choice of a circuit breaker in this case is simple - type C is suitable for most cases. It is available in stores in a large assortment.

Which manufacturers should you trust?

And finally, let’s pay attention to the manufacturers. The choice of a circuit breaker cannot be considered complete if you have not thought about which brand of circuit breakers you will buy. You definitely shouldn’t take on unknown companies - electrical engineering is not a field where you can conduct experiments. Learn more about choosing a manufacturer in the video.

Modern power supply to private houses and apartments is not recommended without circuit breakers. They provide safety and guarantee long service life of the wiring. We will talk about choosing a circuit breaker in this article.

The main purpose of a circuit breaker is to protect the wiring from overheating and the insulation from melting. And it does this by turning off the power supply at those moments when the conductor heats up to critical temperatures due to connecting an excessively high power load. The second task of the package operator is to disconnect the line during short-circuit currents. The goal is the same - to protect the wiring from destruction.

Turning off the power in a timely manner in the event of problems is very important, as it prevents damage to the wiring and fire. Therefore, choosing a circuit breaker is a responsible task. You need to choose according to the rules, and not according to the principle “so that it turns off less often.” This method may cause a fire. In general, the selection of a circuit breaker is carried out according to three parameters:

• denomination;
• breaking capacity (cut-off current);
• type of electromagnetic splitter (time-current characteristic).

Each parameter is important and is selected depending on the load connected to a particular line, the location of the electrical wiring relative to the distribution substations.

Types of circuit breakers

Circuit breakers are produced for single-phase and three-phase circuits. For a single-phase network there are two types of packets - single-pole and double-pole. Only the phase wire is connected to single-pole ones and, when triggered, only the phase is disconnected. It is recommended to install such machines in houses and apartments in rooms with normal operating conditions. Usually they are installed on lighting lines, socket groups, which are located in living rooms, corridors, and kitchens.

Circuit breakers - single-pole, double-pole and three-pole

Both phase and neutral wires are connected to two-pole circuit breakers. He breaks both chains. The degree of protection here is much higher since the shutdown is complete and not partial. Such a machine will ensure safety even if during an accident voltage reaches the neutral conductor. It is recommended to install two-pole circuit breakers on dedicated lines to which powerful household appliances are connected. They are also installed in rooms with difficult operating conditions. These include a bathroom, swimming pool, sauna.

For three-phase networks, three-pole and two-pole circuit breakers are used. All three phases are turned on to three-pole ones. Accordingly, they all turn off at the same time. Such packets are placed at the entrance to a house or apartment, as well as on the lines to which three-phase consumers are connected - a hob, an oven and other similar equipment. For the same consumers, four-pole circuit breakers can be installed. They will also disconnect the neutral wire.

On other power lines, on which one of the phases is used, two-pole packets are installed. Simultaneous disconnection of phase and zero is more preferable. And only on the lighting line can single-terminal circuits be installed.

Selecting a load current circuit breaker

When planning electrical wiring, the main task is to choose the correct circuit breaker rating. When current passes through a conductor, it begins to heat up. The more current passes through a conductor of the same cross-section, the more heat is generated. The circuit breaker's job is to cut off the power before the current draw becomes higher than is acceptable. Therefore, the rating of the circuit breaker must be less than the permissible wiring current.

The ratings of circuit breakers are standardized: 6 A, 10 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A and 63 A. In practice, six and ten amp options are almost never used anywhere - equipment in our homes is becoming more and more and small cross-section lines cannot cope with the load.

Choice of denomination

The circuit breaker is not selected based on the load, the power of the connected devices, or the current. These parameters are taken into account when choosing the conductor cross-section. And the choice of circuit breaker is made depending on the cross-section of the conductors. There is a special table that indicates the permissible load currents and the recommended rating of the circuit breaker. Using the table is simple: find the desired cross-section, in this line look for the rating of the circuit breaker. All.

How it all works

Looking at the table, the question arises: why is the rating of the machine so much less than the maximum permissible current load. The answer lies in the mechanics of the circuit breaker. It turns off only when the current in the circuit is 13% higher than the trip current.

For example, a 10 A machine will work when the current in the circuit is 16 A + 13% (2.08 A) = 18.08 A. That is, there is a small gap left to the permissible load. This gap is required to ensure the integrity of the insulation.

A modern power supply system for a house or apartment cannot do without automatic switches.

What will happen if you install a 16 A circuit breaker on a wire with a cross-section of 1.5 mm2? After all, its rating is lower than the permissible load current? Let's count. The current at which the packetizer will operate is 25 A + 3.25 A (13%) = 28.25 A. It is higher than the permissible long-term load current. Yes, it will rarely turn off, but after a while the insulation will melt and the wiring will have to be changed. Therefore, it is better to select a circuit breaker according to this table, and not according to the long-term permissible current.

Selection by load

If the power supply line is laid with a power reserve, and the load on it is far from the maximum, you can install a machine with a lower rating. In this case, it will protect not so much the line from overheating, but the equipment from short-circuit currents.

Choosing a circuit breaker based on load power is the wrong idea

The choice of the circuit breaker rating in this case can also be made using the same table. Just take the load power as a starting point. But let's repeat it again. This is the case if the line parameters can withstand a much greater load than exists.

Type of electromagnetic splitter (switch-off curve)

The next parameter by which the circuit breaker is selected is the type of electromagnetic splitter. It is responsible for the delay that occurs when triggered. It is necessary to avoid false shutdowns during the start of motors of various equipment.

When you turn on the motor of a refrigerator, dishwasher or washing machine, the current in the circuit increases briefly. This phenomenon is called inrush currents, and they can exceed operating consumption by 10-12 times, but do not last long. Such a short-term increase does not cause harm. So, the electromagnetic splitter must have a delay that allows you to ignore these inrush currents. This characteristic is displayed in Latin letters B, C, D. This letter is placed before the rating of the circuit breaker (photo). Selecting a circuit breaker based on this criterion is not difficult. You just need to know the nature of the planned load:

Actually, choosing a circuit breaker in this case is simple. On the lighting line it is enough to install category B machines; on the rest you can install C.

Selecting the degree of protection against short-circuit currents (cut-off current)

The second function of the protective circuit breaker is to turn off the power when excess currents appear that occur during a short circuit (short circuit). Circuit breakers are designed for different values ​​of these currents, and the characteristic that displays it is the breaking capacity or cut-off current. It shows at what short-circuit current the machine will still remain in working condition. The fact is that the burster does not fire instantly, because there is a delay in response to ignore starting overloads. During this delay, the contacts may melt and the device will become inoperable. So, the cut-off current or breaking capacity shows how much current the contacts can withstand without compromising performance.

In the household electrical network, circuit breakers are used with three degrees of protection against short-circuit currents: 4500 A, 6000 A, 10000 A. On the device body, these numbers are placed in a frame just below the rating of the machine. In terms of price, the difference is quite noticeable, but it is justified - more “resistant” bags use refractory materials, and they are much more expensive.

How to choose a circuit breaker in this case? The choice depends on the location of the network relative to the substation. If a house or apartment is located nearby, the short-circuit currents can be very large, therefore the breaking capacity should be at least 10,000 A. If the household is located in a rural area, the networks there are old and/or the supply occurs via an overhead network, an automatic circuit breaker with a breaking capacity of 4,500 A is sufficient In all other cases they set it to 6000 A.

Housing protection degree

The degree of protection of the case is in the characteristics. It is denoted by the Latin letters IP and two numbers. The first number shows how protected the device is from dust and foreign objects. The lowest level of protection (absent) is 0, the highest level is 6 (complete protection from long-term exposure). The second number indicates protection from moisture. Without protection - 0, maybe in the water for some time - 8. The decoding of the numbers is given in the table.

If the electrical panel is installed in an apartment, in a dry room, the degree of protection IP20 is sufficient. On landings, a higher degree of protection is desirable. At least IP32. If the machine is installed outdoors, you should set it to at least IP55.

Expensive or cheap?

There are two price categories for circuit breakers in stores and markets. One part is produced by well-known brands and has a very respectable price tag. These are Schneider Electric, ABB, LeGrand and others. These brands have been on the market for a long time, have European roots and an established reputation. The quality of their products is always high, so those who do not like to take risks and can afford to spend a lot of money on assembling an electrical panel prefer to purchase products from these manufacturers.

Next to them there are usually the same machines, but they cost 2-5 times less. These are IEK (IEK), EKF (EKF), TDM (TDM), DEKRAFT (Derkaft), etc. These are Chinese machines, but produced in factories. Some brands (the same Dekraft) have European roots (in this case Germany), but production facilities are in China. These brands are also considered quite good and show stable results. So for those who try not to spend extra money, this is a good option. Affordable and good quality.

What you should not do is buy products from unknown manufacturers. Even if their price is very attractive and the seller praises them very much.

There are also pitfalls when buying famous brands: there are too many fakes. Moreover, they are sold at almost the same price as the original and it is very difficult to distinguish them by external signs. The only thing you can focus on is less weight. Counterfeits contain less metal and may be missing some elements. Due to this, the weight is less. There may also be errors in the application of inscriptions; sometimes paints of other shades are used. To notice all this, you must first thoroughly study all the nuances of the originals on the official websites, or even better, hold them in your hands.