Antipyretics for children are prescribed by a pediatrician. But there are situations of emergency care for fever, when the child needs to give the medicine immediately. Then the parents take responsibility and apply antipyretic drugs. What is allowed to give to infants? How can you bring down the temperature in older children? Which medications are the safest?
During installation electrical wiring some "competent" customers ask why I put a 2.5 mm² wire on the sockets rather than 1.5 mm² as a luminaire and why in some cases I use a wire with a cross section of even 4 mm². They are not interested in idle curiosity, but because the larger the cross-section of the wires, the more expensive it is. In this article I will try not only to answer them, but also to all comers, why and how to choose wire cross-section for this or that site electrical wiring in an apartment or a private house.
Based on how correctly and correctly we select the section of mounted wires and cables, our household electric consumers will work so reliably and long.
As we know, all electrical wiring begins with an input cable - a cable that is laid from a power line (power line) to a common (input) or electric meter. This wire carries the entire total load of all consumers who are in an apartment or house. In order to determine the cross-section of the conductors of the input cable, you need to know the total power (Watt) of all electrical appliances installed in your home - microwave, air conditioning, washing machine, water heater, electric stove, etc. It is necessary to take only powerful devices, small ones can be ignored, such as a razor, a coffee grinder, a small TV, etc. Having combined the power of the devices, we will get the total power of all our consumers. Multiply this figure by a factor of 0.75 and obtain a cross-section of the phase (or phase) core of the input cable. The cross-section of the zero core is allowed a little less, or the same.
Another aspect: when calculating the total capacity it is necessary to take into account the capacities of only those consumers that will be included in the electric grid simultaneously. Otherwise your calculations can lead to the selection of a wire cross-section with a small tree!
The power of the household electric appliance can be found either on its housing or in the technical passport, which is attached to it.
Below is a table with which you can determine the cross-section of the wire you need, while knowing the power consumption on this line of electrical wiring. Or vice versa: knowing the cross-section of the cores, you can determine what current and power it can pass and sustain. The table shows the values for a copper wire, since aluminum wires are forbidden by the Electrical Installation Device (PUE) Rules.
Cable and wire section selection table
Then we will need to calculate the cross-section of wires and cables for the line of outlets and the line of illumination.
If we start only from our table or formulas for calculating the cross sections, it will be that a 1.5 mm² wire is sufficient for the line of outlets, and for the lighting line, less than 1.5 mm². But in practice, the wires are mounted here such a section: for sockets - at least 2.5 mm², for lighting - at least 1.5 mm². Why is this done?
As for the lighting line, it is not possible and inexpedient to mount a wire with a cross section of less than 1.5 mm². This is justified by the fact that it will not withstand mechanical loads and chemical reactions (oxidation). A laying of wire for sockets with a cross section of at least 2.5 mm² is provided in order that in the future you can include in them electrical appliances of higher power than there is at the moment. For example, you had an iron for 1.5 kW, it went out of order, you bought a new 2.5 kW. Do you really need to change the whole electrical line for this outlet because of this?
With regard to the cross-section of wires in the wiring and protection devices, their installation is also carried out based on this table. For example, for outlets in the kitchen, you pulled a 2.5 mm wire that withstands an electric current of 27 amps and is rated at 5.9 kW. In the switchboard for this line of electrical wiring with a socket is installed a circuit breaker or an RCD with the maximum current operate no more than 25 Amps.
Also, when designing the electrical wiring, the length of the main line, which will feed the final consumer of the electric current, should be taken into account. Also, during the design, and then, do not forget about the selectivity of machines. Selectivity is a specific feature of relay protection to detect a damaged wiring element (short-circuit, overload) and disconnect it by nearby circuit breakers, without stopping the normal operation of the remaining zones of the electrical circuit.
What cable cross-section for outlets should be in the apartment? This is a very important issue, when all the wiring changes to copper, instead of old, from aluminum. After all, it is important that the wires withstand all electrical devices, which are in your house. And today there are a lot of them, and they consume electricity in large amounts, respectively. But for this, before asking yourself how to connect the cable to the outlet, it is important to understand how many outlets you need.
Only after you figure out all these issues, it's to talk about choosing a cable cross-section in terms of power. Undoubtedly, the most the best options, these are copper wires. In which the whole cores, well, or, in extreme cases, multi-core, as well as excellent isolation of vinyl. One thing surely pleases that today in the store or in the market you can buy these products, and it is offered in the widest range. To connect internal sockets, the wires should have a cross-sectional diameter of two and a half sq. mm. And when using sockets in which there is grounding, you will need wires in general, three-core, and with the same cross-section. Choosing a cross-section of the cable for wires that illuminate the room, the diameter will fit in a half a square. mm.
Cable cross-section - where and how to use?
Wires for room lighting coming from the separation box are laid separately from the wire to which the sockets themselves need to be connected, since they consume much more electricity, which is why they become too hot. Accordingly, they are connected to very powerful electrical appliances. If you find it difficult to calculate the cross-section of the cable, do not worry. In fact, it's not at all difficult, moreover, in this also to your help our cable section table!
If we talk about stationary electrical appliances having a high power, then here it is necessary to lay a separate wire with a large cross section. Here we are talking about an electric stove, a microwave oven, a washing machine. Well, before buying wires, it is important to accurately make a miscalculation of the required footage. Let it stay a little better than not be enough.
To save time and nerves, take, ten percent "in reserve."
For each room in your home you need one junction box. In this case, it is correct to conduct the wire from the reading machine itself to each junction box, separately.
Power in junction boxes
For each of the rooms, you should calculate the total, connected to the junction box, the power. This will help you to find out what their total power is, and also to find out which cross-section you need to choose, including from switchboard - to the junction box.
If in total the power of the devices is a maximum of three kilowatts, a diameter of two and a half millimeters is needed. As for the kitchen area, in which there are a lot of powerful electrical appliances, the wire cross section should be 6 square meters. mm.
Replacement of electrical wiring is a complicated matter, and not everyone can. If you belong to those who doubt their capabilities to solve this issue, then it is definitely worthwhile to hire a specialist who will perform the work qualitatively and promptly.
Calculation of the cable cross-section for concealed wiring
| Cable cross-section, mm² | copper. Here prices for copper scrap in Moscow very profitable. | aluminum | ||||
| current A | kW | current A | kW | |||
| 220V | 380V | 220V | 380V | |||
| 1,0 | 14 | 3,0 | 5,3 | |||
| 1,5 | 15 | 3,3 | 5,7 | |||
| 2,5 | 21 | 4,6 | 7,9 | 16,0 | 3,5 | 6,0 |
| 4,0 | 27 | 5,9 | 10,0 | 21,0 | 4,6 | 7,9 |
| 6,0 | 34 | 7,4 | 12,0 | 26,0 | 5,7 | 9,8 |
| 10,0 | 50 | 11,0 | 19,0 | 38,0 | 8,3 | 14,0 |
| 16,0 | 80 | 17,0 | 30,0 | 55,0 | 12,0 | 20,0 |
| 25,0 | 100 | 22,0 | 38,0 | 65,0 | 14,0 | 24,0 |
| 35,0 | 135 | 29,0 | 51,0 | 75,0 | 16,0 | 28,0 |
Calculation of the cable cross-section for external wiring
| Cable cross-section, mm² | copper | aluminum | ||||
| current A | kW | current A | kW | |||
| 220V | 380V | 220V | 380V | |||
| 0,5 | 11 | 2,4 | ||||
| 0,75 | 15 | 3,3 | ||||
| 1,0 | 17 | 3,7 | 6,4 | |||
| 1,5 | 23 | 5,0 | 8,7 | |||
| 2,5 | 30 | 6,6 | 11,0 | 24 | 5,2 | 9,1 |
| 4,0 | 41 | 9,0 | 15,0 | 32 | 7,0 | 12,0 |
| 6,0 | 50 | 11,0 | 19,0 | 39 | 8,5 | 14,0 |
| 10,0 | 80 | 17,0 | 30,0 | 60 | 13,0 | 22,0 |
| 16,0 | 100 | 22,0 | 38,0 | 75 | 16,0 | 28,0 |
| 25,0 | 140 | 30,0 | 53,0 | 105 | 23,0 | 39,0 |
| 35,0 | 170 | 37,0 | 64,0 | 130 | 28,0 | 49,0 |
| Copper wires | ||||
| Voltage, 220 V | Voltage, 380 V | |||
| current, A | power, kWt | current, A | power, kWt | |
| 1,5 | 19 | 4,1 | 16 | 10,5 |
| 2,5 | 27 | 5,9 | 25 | 16,5 |
| 4 | 38 | 8,3 | 30 | 19,8 |
| 6 | 46 | 10,1 | 40 | 26,4 |
| 10 | 70 | 15,4 | 50 | 33,0 |
| 16 | 85 | 18,7 | 75 | 49,5 |
| 25 | 115 | 25,3 | 90 | 59,4 |
| 35 | 135 | 29,7 | 115 | 75,9 |
| 50 | 175 | 38,5 | 145 | 95,7 |
| 70 | 215 | 47,3 | 180 | 118,8 |
| 95 | 260 | 57,2 | 220 | 145,2 |
| 120 | 300 | 66,0 | 260 | 171,6 |
| Current conductor cross-section, sq. Mm | Aluminum wires | |||
| Voltage, 220 V | Voltage, 380 V | |||
| current, A | power, kWt | current, A | power, kWt | |
| 2,5 | 20 | 4,4 | 19 | 12,5 |
| 4 | 28 | 6,1 | 23 | 15,1 |
| 6 | 36 | 7,9 | 30 | 19,8 |
| 10 | 50 | 11,0 | 39 | 25,7 |
| 16 | 60 | 13,2 | 55 | 36,3 |
| 25 | 85 | 18,7 | 70 | 46,2 |
| 35 | 100 | 22,0 | 85 | 56,1 |
| 50 | 135 | 29,7 | 110 | 72,6 |
| 70 | 165 | 36,3 | 140 | 92,4 |
| 95 | 200 | 44,0 | 170 | 112,2 |
| 120 | 230 | 50,6 | 200 | 132,0 |
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If you, yourself think to do a replacement wiring at home, change the current to a new one. The question arises, what to do first, what section should be the wire for the sockets? At the very beginning, it is necessary to see whether it is possible to change the wires completely - this is one option, or to use the one that is, and from it to make new sockets and switches - this is another option. The second option is easier, simpler and very cheap (but there is no guarantee that it is safer).
Proceeding from this, we will consider the number one option. First it is necessary to make a project (it needs to be coordinated in Energonadzor).
You can connect the house to the food in two ways. For example, all premises are connected to a electric counter by means of one machine, the sockets are connected to another, or it is possible (the most correct variant) to connect each room to electricity with the help of an autonomous machine. The automatic machines are connected on the switchboard near the meter. The positive properties of this connection is that if there is a malfunction or other need, you can disconnect the necessary room from the network, and in the remaining rooms there will be electricity.
In any room, you can put a mark on the wall where you want to make electrical outlet and switches. According to the latest standard, the switches are located at a distance of 80-90 cm from the floor, but preferably, of course, at a distance of the lowered arm (for comfort). It is necessary to take into account that the sockets are not behind the wall of furniture or under the pictures. They are mounted approximately 30 cm from the floor Banquet in the hallway with shelves for shoes .
Why not save on rosettes
You can not save at the expense of outlets. In one room they should be made 2-3, appearance the room will not suffer from this. In the kitchen, the sockets are attached above the kitchen table, but not over the gas stove or above the sink.
Next, go around the rooms and count how many "points" came out. For one given point, you need to buy a box in which the sockets and switches will be located. Do not forget that you need to purchase switches and sockets, both single and double, as well as sockets equipped with a grounding wire and without it (often, appliances working in the kitchen and bathroom are subject to grounding, and in the bathroom, in addition, it is necessary install sockets with safety caps).
How to choose the right connection cables for sockets
Now consider the connecting wires. What should be the wire cross-section for the sockets? The most suitable for this is a wire with copper stranded with double insulation, such as VVG. A wire with a cross-sectional diameter of more than 2.5 mm2 is connected to the sockets, and to triplets with a grounding - a triple wire of this diameter. The wire for lighting is used with a diameter of 1.5 mm2. IMPORTANT: wires for lighting for sockets stretching separately from the distribution box. For energy-intensive stationary electrical appliances, such as an electric stove, a washing machine, it is also necessary to pull out separate grounded wires. An electric stove or oven is connected by a wire with a diameter of more than 4 mm2.
Next we need distribution boxes, which are installed in each room. As it was determined earlier, from the start-up device the main wire will be held separately in each room to the junction box. Count in advance how many and which appliances consuming electricity will be located in each room, and calculate their total power. From this indicator will depend on what diameter the main wire must be stretched from the electrical panel to the junction box. Most often, the main wires take a diameter of 2.5 mm2. This is perfect for a room with a total power of at least 3 kW. What section should be the wire for the sockets in the current kitchen, where the number of electrical appliances is very much the main wire should be taken with a diameter of 4-6 mm2, and when installing an electric oven in the kitchen - the diameter of the wire is taken according to the specification shown in the passport on the stove.
Let's sum up, the power is calculated, the diameters of the wires are determined. Next, you need to calculate the length of the wires from all junction boxes and the way of their extension to the fixed starters on the shield. Wires need to take a length of 1-2 meters more than the calculated, in order to have a single wire along the entire length of the gasket. Strictly forbidden to use the main wires, twisted from the pieces.
What advice to give in addition? If you live in a multi-storey building and the electricity meter is in a common shield on the site, then it is necessary to put an autonomous electric board in the apartment, as written above.
Let's sum up the section of wires:
- work on the electrical start the very first (hollow the recesses for the boxes and for the sockets, switches, junction boxes, shred the grooves for the wires) and finish with the very latest (installation of lamps, sockets, etc.).
- when choosing a socket, look at the method of fixing the wires. In imported sockets, clamping devices are used, into which the wire is inserted elementally. These sockets are easy to install and carry heavy loads.
- in a single unit it is allowed to place sockets and switches together.
- for the bathroom it is necessary to install a separate RCD with an estimated leakage current of 10 mA.
- if you do not do the wiring yourself, then entrust all the necessary electrical work to highly qualified specialists or organizations that have the necessary licenses.
Video review the choice of cable or wire cross-section
