If you decide to do it in your home, then remember that you should make an estimate for the materials. This is necessary to calculate the cost of electricity installation work. Thanks to this, you will never again face the problem of not having enough money for sockets or switches.
After compiling a special table, you can easily understand whether you have enough material resources or whether you need to switch to a choice of cheap materials. Now in this article we will tell you how to make an estimate for electrical work. Here you will find videos and instructions to help you complete these tasks.
Document preparation
Before installing wiring, you need to prepare documentation. Based on all the documents, you can draw up the necessary diagram. To perform calculations, you will need the following documents:
- Plan of the room in which you plan to install electrical wiring.
- A project that will indicate the placement of electrical equipment.
- Technical specifications that you can easily obtain from the supplier.
- Permission for future connection to the electrical network.
Depending on the situation, additional elements may also be required. These include: a document on the limitation of operational liability, a work order for the supply of finished electrical equipment. In most cases, these documents can be used in enterprises. To draw up an estimate for electrical work in a residential building, it will be enough to simply prepare the first two documents.
How to calculate the cost of electrical installation work
Calculating the cost of installing electrical wiring is quite simple. The only thing you may need is responsibility for carrying out such a procedure. The more points you can include in the estimate, the less chance you have of overpaying. Drawing up an estimate for electrical installation work will consist of the following steps:
- Getting a room plan linked to electrical appliances. You can find a similar plan in the BTI.
- Obtaining permission to connect to the electrical network.
- Correct cast technical specifications to the standards.
- Search for profitable materials.
- Final calculation of all costs.
If, after drawing up a diagram for electrical installation in the house, you realize that you do not have enough money, then you should reconsider your project. You can also simply replace expensive appliances with cheaper ones.
This instruction is perfect for people who want to independently calculate the cost of electrical installation. If you are not confident that you can correctly draw up an estimate for electrical installation work, then you should contact a specialist. Another and most important point is who will do the electrical installation. Do you want to do your own electrical wiring? own home? Then you just need to skip this moment. If the electrician will be carried out by a company, then you should first find out how much the cost of electrical installation or dismantling will be. If you live in old apartment, then the dismantling service should be indicated in the estimate.
At the moment, many companies that offer their services have their own, which allow you to quickly calculate the cost of electrical installation. If necessary, you can find prices for the installation of certain electrical points yourself. Thanks to this, you can easily calculate the cost of electrical installation work at new prices.
Estimates today may have a number of differences. The most common options include complex or local estimates. You can create your own cost plan in Microsoft Excel. After switching to the program, you just need to create a table. All formulas and data should be written down in the table. If you want to know how to prepare an estimate for electrical work in Excel, then you can find this information in the video.
Prices for 2016-2017
This is the last information we want to bring to your attention. These are approximate prices for electrical installation in residential premises. In 2016-2017, the cost of electrical installation will be as follows:
- Installation of 1 meter of cable channel will cost 150 rubles.
- Cable laying open method 50 rubles per meter.
- Installation circuit breaker 500 rubles.
- Installation of socket 250 rubles.
- Installation of a shield from 2000 to 5000 rubles. It all depends on the complexity of the work.
- Connecting a sconce costs 500 rubles.
These are the basic prices for electrics that you can find in various companies. When drawing up your own estimate for electrical wiring work, you can use them as a guide.
The total cost of electrical installation in 2016-2017 will be:
- 20 thousand rubles in a one-room apartment.
- 30 thousand in a two-room apartment.
- 40 thousand in a three-room apartment.
- 100 thousand in wooden cottage up to 100 sq. meters.
- 75 thousand in brick house up to 100 sq. meters.
These are the prices that you need to focus on when using the services of an electrician.
This is all the information we wanted to convey about how to make an estimate for electrical work in an apartment or house. We hope our information will be useful and interesting.
In multi-storey buildings, communications are laid by the builders, and there is no need to install the electrical network yourself, but if you are building a house, electrical wiring calculation will definitely be needed.
1 Where does the electrical wiring calculation begin?
Scientists still have a rather vague idea of what current is. It is known how to use it, it is known how to change it, how to direct it, but all its properties and features have not been solved. However, today it is impossible, or very difficult, to do without a stream of electrons running along a cable, especially for those who are accustomed to comfort. Light, heat, fresh conditioned air, communications, and often cooking - all this provides us with electricity, which powers all kinds of household and industrial equipment. In order for current to start flowing into a house or area, it is not enough to simply stretch the wires; you need to know exactly what material they should be made of and what cross-section. But let's take things in order.
Electrical wiring calculation
Using the buttons, draw up a diagram of the planned electrical network.The wire goes:
Wire used Copper Aluminum
Exit from the counter
Add a wire going to...
Calculate wire cross-sections -
It is also known from a school physics course that current has parameters such as power, voltage and, in fact, a certain force determined by the intensity of movement of charged particles. It is recommended to start calculating electrical wiring with the ratio of these quantities, which influence many factors when choosing a cable and other network elements. The formula looks like this: P = I U, Here P– power, measured in Watts (W and kW), I– current strength (Amps, A), U– voltage (Volts, V). Based on the formula, you can find any parameter if the other two are known.
The cable cross-section is directly related to the current strength. If you take a wire 0.5 mm2 thick and pass 17 Amperes of electricity through it, the wiring will simply burn out, since with such a current strength you need a copper or aluminum core of 1 mm2. In addition, its ability to maintain a certain power at a particular voltage depends on the cross-section and material of the cable. The following is a table that will help you select the desired wire diameter for various network options.
Dependence of cable cross-section on current strength
|
Open wiring |
Closed wiring |
Cable cross-section mm² |
||||||||||
|
Copper |
Aluminum |
Copper |
Aluminum |
|||||||||
|
Current A |
Power kW |
Current A |
Power kW |
Current A |
Power kW |
Current A |
Power kW |
|||||
2 How to calculate electrical wiring on a site
In the local area, along, sometimes even in the garden and flower bed, as well as along the perimeter of the site, there is always some kind of lighting. And if some especially economical owners find it more convenient to use lanterns and decorative lamps on solar powered, then traditionally power lines from the nearest substation are stretched to the land plots. This can be an overhead cable or underground; in the first case, it passes through insulators on the tops of the poles, and in the second, through a special dielectric pipe buried deep in the ground.
Based on how electricity is supplied, it is necessary to calculate the continuation of the line on the site. The simplest solution is from two wires, one of which is phase and the other neutral, sometimes a house may have three wires to provide two separate phases. A four-wire input is necessary if there is a need for a three-phase version, if there is an appropriate consumer (industrial and professional equipment, machine tool). The latter type of connection can only be used after obtaining permission from the electricity supply organization.
So, let's focus on a single-phase two-wire connection to the substation, which still needs to be extended if you do not want to pay for the work of specialists. Before calculating the electrical wiring, you should take into account that the length of the cable from the common line to your site should not exceed 25 meters; at a greater distance (and in case of strong winds in your area and at a shorter distance) you need to install a support. The height of the cable above the road is at least 6 meters; it is advisable to install an overhead line into the house at a level of 3 meters.
At the output from the substation where the transformer is located, the current usually already has a voltage of 220 V. But drops in electrical network- this is a common thing, and it may turn out that you are receiving some 160 V. To obtain the required voltage level, you need to install a stabilizer at the cable input, as well as circuit breakers that will protect the network from overload. Their parameters are indicated in Amperes, that is, they are measured against current consumption. Having completed the distribution panel, we place it in a place where there is no dampness.
To everyone outbuildings, be it a barn or a summer one, wires are pulled, this can be done by air and directly, it will be more economical. It is better to provide lighting along the paths with an underground cable, and the lights should be connected in parallel rather than in series, so that the burnout of one lamp does not turn off the entire circuit. We take a plan, and on it we mark the overhead line connecting the buildings with the distributor, and the underground cable stretching from it along the paths (and repeating all their bends). We measure the resulting wiring and multiply its length by 2, since at least two wires are needed (double insulation is recommended on the street), for phase and zero.
3 House wiring calculator
To begin with, we calculate the power of the machine for all current consumers present and switched on simultaneously. If your refrigerator and computer are working, and you still start washing machine, to supply which water is needed instantaneous water heater and a pump, then the consumption will be about 11 kW. This is even if we exclude lighting. It is logical that a 16 A machine will not withstand such a load. You can see what power these or other devices have in the following table; then, using the above formula, we calculate the rating of the machine.
Power of electrical appliances (W)
| Hair dryer | 1200 | Drill | 800 |
| Iron | 1700 | Hammer | 1200 |
| Electric stove | 3000 | Electric sharpener | 900 |
| Toaster | 800 | Circular saw | 1300 |
| Coffee maker | 1000 | Electric planer | 900 |
| Heater | 1500 | Jigsaw | 700 |
| Grill | 1400 | Grinding machine | 1700 |
| Vacuum cleaner | 1600 | Water heater | 5000 |
| Printer | 100 | Washing machine | 2500 |
| TV | 300 | Compressor | 2000 |
| Fridge | 300 | Water pump | 1000 |
| Microwave oven | 1400 | Circular saw | 2000 |
| Computer | 500 | Air conditioner | 1500 |
| Electric kettle | 1200 | Electric motors | 1500 |
| Full coverage | 1000 | Fans | 1000 |
| Boiler | 1500 | Lawnmower | 1500 |
| Air fryer | 1700 | Welder | 2300 |
| Radio | 70 | Concrete mixer 70 liters | 250 |
| Compressor treatment plant(VOC) | 200 | Infrared heater | 600 |
To install the electrical network, branch boxes are used, from which the wiring is pulled into adjacent rooms.
It should be remembered that when wiring the electrical network around the house, you need to immediately divide it into three groups, one of which is allocated entirely for lighting fixtures, the second is for sockets, and the third is used for devices that require grounding. This will make it easier to calculate the electrical wiring calculator. In this case, in no case should you use one neutral cable for two different groups, as well as combine them with each other. It is also necessary to provide each individual group with its own automatic protective switch, the rating of which is calculated from the sum of the powers of the devices connected to this wiring.
If the wiring in the house is functioning normally, then excess heat is simply dissipated into the surrounding space, without negatively affecting either the electromechanical characteristics of the cables or the quality of the power supply. And if the calculation of the electrical wiring was carried out incorrectly, then already in the first days of its operation you may detect a violation of the integrity of the conductive conductors and the insulating layer. This happens due to simple overheating, which was caused by your own hindsight.
If you take on the task of installing the wiring yourself, you need to measure and calculate everything. For this you will need a regular tape measure. Take into account all the corners, protrusions and niches, count the number of electrical appliances that you and your household will use and multiply the final figure by 15%. This is the standard margin during technical calculations.
If you want to run around with a tape measure around a three-story cottage or an apartment of 300 square meters. you don’t have meters, but you still need to know at least an approximate figure, you can use a simple approximation: multiply the total area of all residential and non-residential premises in square meters by 2. Your apartment has an area of 72 square meters. m - you need to buy about 150 meters electric cable. Spotlights, wall sconces, LED strips, chandeliers - all this requires an insane amount of wires.
What if you need more than one type of cable? Take it at the rate of 1:2 - one part will go to lighting the apartment, the other two will go to its power supply. For laying individual cables " special purpose", - to the electric stove, air conditioners, washing machine you will have to make accurate measurements, and for small household appliances you can buy a regular three-core wire.
Types of wires and cables - the choice is huge
Correct calculation of electrical wiring
When making calculations in a house, electricians suggest buying three-core wires or cables with aluminum or copper cores enclosed in polyvinyl chloride insulation. Such materials are ideal for hidden wiring- do not heat up and can last for decades. These cables are also suitable for an open installation method - this method currently practically not used.
Old wiring is a source of increased danger
In the table you will find data on the type of cable and its maximum current strength and use this information in your calculations.
Table for calculating cable cross-section depending on the load
Bandwidth electrical wiring is determined not in kilowatts, but in amperes. When it comes to calculating wiring for connecting a section of a circuit or some device, you need to start from power, that is, from kilowatts. The relationship can be expressed by the following formula:
P=U∙I∙cosφ ,
where P is the connected power of the device (W), U is the voltage (V), and cosφ is taken as one if the calculation of electrical wiring in an apartment is carried out for large areas, or it is omitted altogether if the apartment or house is of modest size.
We express the force as the ratio of connected power to voltage by the formula:
I=P/U .
Let's calculate the power in a single-phase circuit with 10 standard incandescent lamps connected to it, power 100 W each, one microwave power 1 kW and 2 kW electric kettle.
Total power of all devices: 10x100+1000+2000=4000 W. The mains voltage is 220 V (let’s take a reference figure). Dividing the power by voltage we get 18.18 A. That is, in the area we are calculating electrical circuit The current is 18.18 A. Now look at the table and decide for yourself which type of wire is most suitable.
Do you need power reserve?
When installing wiring, the power reserve must be taken into account - everything must be within reasonable limits. Some electricians suggest buying a cable with a cross-section of 6 mm2 for a regular room (children's or bedroom), while the input cable for the entire house or apartment has a core cross-section of 4 mm2. They explain thriftiness simply: the more devices there are in the house, the more cable is needed. This power reserve is not needed - it will only lead to additional costs for the purchase of cables and their installation.
Correctly performed calculation of electrical wiring power will save money, while the electromechanical characteristics of the conductors will not be affected. This applies not only to the cross-section of the wires, but also to the structure of the line. A single-line diagram will reduce the length of cables, reducing installation time and material costs.
A little about protection and “accessories”
Devices protective shutdown instantly disconnect the network if a leak in excess of the nominal value is detected. To protect the entire network, you need to use circuit breakers that will instantly respond to short circuits or overload and will disconnect the network from power.
For a typical city apartment you will need: a copper or aluminum cable with a cross-section of 1.5 mm2, rated for a current of 16 A (the figure may be different, depending on your home), a cable with a cross-section of 2.5 mm2 for sockets, rated for a current at 25 A, circuit breaker - 10 A and 16 A. You can find out the power consumption of electrical appliances from the technical data sheet.
Final electrical wiring (before finishing works)
There are a lot of other aspects - temperature correction factor environment, coefficient for jointly laid devices, which must be taken into account when calculating electrical wiring. Therefore, for your own peace of mind, contact specialists, especially when your apartment will use energy-intensive appliances and powerful electrical receivers with reactive loads. They will calculate the full power supply project for your home without any problems, all you have to do is bring it to life.
Before proceeding with the installation of electricity in the house, you need an estimate for materials. This is necessary in order to calculate approximate (or even exact) costs and during electrical installation do not encounter a situation where there is not enough money for sockets or switches. Based on the prepared cost table, you can understand whether there are enough materials or whether it is better to purchase cheaper materials in order to certainly avoid problems with shortages. Next, we will tell you how to create an estimate for electrical work, providing step by step instructions with video and also a sample.
Step 1 – Prepare documents
The first step is to prepare documentation on the basis of which an estimate for electrical installation will be drawn up. For calculations you need to collect the following documents:
- A floor plan showing the electrical wiring diagram.
- Electrical equipment placement project.
- Technical conditions that need to be obtained from the electricity supplier (if necessary). We talked about this in a separate article.
- Permission to connect to the electrical network (if necessary).
In addition, depending on the situation and characteristics of the facility, you may need a statement of balance sheet ownership, a document on the limitation of operational liability, as well as a work order for the supply of electrical equipment. All these documents are mostly used in enterprises. As a rule, in order to draw up an estimate for electrical installation work in a residential building, it is enough to prepare the first 2 documents from the list, as well as a permit for electrical installation.
Step 2 – Perform the calculation
Calculating the cost of installing electrical wiring is not too difficult, but you will have to take this procedure quite seriously. The more points are indicated in the estimate, the less chance that after the electrical installation is completed, situations will arise that will require you to overpay. So, drawing up an estimate for electrical installation work consists of the following steps:
- Obtaining a floor plan linked to electrical appliances. You can take it to the BTI.
- Registration of permission to connect to the electrical network.
- Bringing all technical conditions to the standards.
- Calculation of the amount of materials based on the electrical wiring diagram.
- Search for the best deals on materials.
- Cost calculation.
If, after you have drawn up an estimate for the project, it turns out that there is not enough money, you will have to reconsider the project and, if possible, either remove some electrical points or purchase cheaper materials.
This instruction is suitable for those who want to independently calculate the cost of electrical installation. If you doubt that you can correctly draw up an estimate for electrical installation work, it is better to entrust this matter to specialists, but they, of course, will take money for it. Another important point– who will do the electrical installation. Would you like to do your own electrical wiring in your own home? Then you miss this moment. If it is assumed that the electrical work will be carried out by a company or a private electrician, it is necessary to find out what the cost of electrical installation will be, as well as dismantling the old network (if the apartment is not a new building) and be sure to include this figure in the estimate.
Please note that many companies offering electricity installation services have their own online calculators on their websites, with which you can quickly calculate the cost of electrical installation. There, as a rule, you can also find prices for the installation of certain electrical points (sockets, switches, meters), laying cables and gating walls for wiring. This information will allow you to easily calculate the cost of electrical work at new prices.
It should also be noted that estimates can be comprehensive (for the entire facility) or local (for a separate room/premises).
The best way to create a cost plan is in Microsoft Excel. All you need to do is download this program to your computer, install it and create a table in it. Next, enter all the values into the table, and then make calculations based on the formulas. How to prepare an estimate for electrical installation work in Excel is clearly explained in the video example:
Sample of calculation works
Prices for 2017
Well, the last thing I would like to provide is estimated prices for electrical installation in residential premises. So, in 2017, the cost of electrical installation is as follows:
- installation of a cable channel (1 m.p.) – 100-180 rub. (depending on the material of the walls and the size of the product);
- Open cable laying 50 RUR. per linear meter, 60 for hidden electrical installation;
- installation of a circuit breaker - 300-600 rubles;
- installation of a shield - from 1000 to 5000 rubles;
- connecting a wall sconce – 500 RUR;
- installation of socket – 250 RUR.
These are the basic prices for electricians, which we recommend using as a guide when drawing up an estimate for electrical wiring work. In general, excluding the price of materials, the cost of electrical installation in 2016-2017 will be (in rubles):
- one-room apartment: 20 thousand if the walls are made of brick, 25 thousand if they are concrete;
- two-room apartment: 30 thousand (brick), 35 (concrete);
- three-room apartment: 40 thousand (brick), 45 (concrete);
- wooden cottage: up to 100 sq.m. 65 thousand, over – from 95 thousand;
- brick house: up to 100 sq.m. 75 thousand, over – from 110.