Calculation of electrical loads is performed in order to choose the right wire size, which will be laid mains. If all network parameters (voltage, current and electrical resistance) will correspond to each other, it will last a long time, will not overheat, and therefore will not cause a fire.
Instruction
1
Calculate the maximum load on the electricity network. To do this, define the maximum capacity of consumers that can be simultaneously connected to it. Then define the material of the conductor, which will be done wiring. To do this, take a copper wire, it has a higher conductivity than aluminum and not so quickly burn out at higher load.
2
Calculate the wire size required for proper load distribution. To do this, the total power of all consumers, which can be found in the technical documentation on them, divide by the nominal voltage. The result is the maximum value of current which needs to flow (I=P/U). Domestic and industrial network are made so that the source voltage was the same on all connectors (sockets).
3
After determining the maximum flow in the power network, locate the wire cross section, from whence the network. Please note that the maximum current density for aluminum wire is 5 A/mm2 and for copper - 8 A/mm2. Install a fuse with a nominal value, minimum maximum circuit current, to avoid burnout of the conductors in the network in case of a short circuit.
4
Example If on a country site it is necessary to calculate electric load, add up the number of power appliances that may be included in the network. Lighting 10 lamps of 100 Watts (1 kW), boiler 4 kW, 0.5 kW refrigerator, microwave oven 2.5 kW, smaller household uses 2 kW. In sum, we obtain the capacity of 10 kW=10,000 watts. As in the home network, the effective voltage value is 220 V, calculate the maximum current in the network I=10000/220≈45,46 A. For network devices use the aluminum conductor section of at least 45,46/5≈10 mm2 or copper 45,46/8≈6 mm2. Install a fuse with a nominal value of at least 46 A.

# Advice 2: How to calculate electrical power

The powerconsumption of those or other electrical device, is measured by wattmeter. But it is not every DIY enthusiast. In its absence it is possible to measure other parameters of the circuit, which includes the consumer, and then based on these data to calculate the power consumption.
You will need
• One or two multimeter
• The meter
• Switch
Instruction
1
In most cases, at home worker, there is only one multimeter that can be switched in turns to the measuring mode current, mode voltage measurement. In this case, first switch the mode to measure voltage, selecting the right limit and type of current. Connecting the multimeter in parallel to the disconnected consumer (if it is powered by direct current - the polarity), plug it in, and then, measuring the voltage across it, remember or write down the result. Disconnect power from the load.
2
Switch the multimeter mode to measure the current, also selecting the right limit and type of current. Connect it in series with the consumer (when powered by direct current also observing polarity). If the starter load current significantly exceeds the worker, sexunderwate multimeter switch and lock it.Turn on the power load. If the multimeter is bridged by a switch, after the release of the consumer desktop mode, open it. Read the result, and then remember or write it down. Disconnect power from the load.
3
If you have two multimeter, inserting them appropriately, it is possible to measure the voltage across the load and current consumed her at the same time. Thus, working with the customer, starting current which is much higher than work, and do not forget to shunt multimeter, playing the role of the ammeter, the switch, opening it only after the load operation mode.
4
Multiplying the voltage to the current, calculate the power.
5
If the load is powered by the lighting network, to measure consumed her power by using the meter. Of course, the counter, which is located in a Cabinet in the stairwell, you will not do, because in order to use it as a power meter had to be turned off in the apartment all the other consumers such as a refrigerator, which is extremely inconvenient. You will have to use a separate meter, and not necessarily sealed and have passed the calibration, since for its intended purpose it will not be used.Enabling the user through the counter, count how many revolutions will it make the drive for a certain period of time. Looking at the front of the counter, how many revolutions of the disc corresponds to one kilowatt-hour, disconnect the load, and then calculate consumed her power according to the formula:P=(n/N)/(t/60) where n is the measured number of revolutions, N is the number of revolutions corresponding to one kilowatt-hour, t - duration of measurement in minutes.
Note
Instead of a multimeter, which plays the role of the ammeter, it is convenient to use a clamp on meter (clampmeter). This device allows you to measure current without breaking the circuit. Switch for protection against high inrush current is not required.

# Advice 3: How to calculate the lamp power

For proper illumination of rooms, corridors or free-standing object, such as aquarium, you need to determine the appropriate type of lamp: number, location and capacity of the installed lamps. There are a few rules, doing that, just to perform this task.
You will need
• roulette, sheet of paper, pen, calculator
Instruction
1
For the General calculation of the lamps use the following formula: P=pS/N, p –power, the specific lighting, measured in Watts per square meter (the average is 20 Watts per square meter), S is the area of the premises, for which this lamp is calculated in square meters and N is the number of lamps.
2
Example: calculate the room measure the length and width of the room. The results obtained (for example, 3.3 meters long and 4.5 meters wide) between multiply and get the area of this room (3,3 × 4,4 = 14,85 square meters). This figure multiply by 20 and divide by the expected number of bulbs in lamps. For example, take the 3 lamps on 2 lamps in each. In this case, 14,85 multiply by 20 and divide by 6 (3×2=6). Get the result, which means that in this case, you have 6 lamps at 49.5 Watts.
3
Can vary the wattage in each lamp, dividing the room into several zones with different lighting. The total power of all lamps in the room should not be less than 297 Watts.
4
In some cases it is necessary to take into account the specifics of the premises, which make the calculation of the total power of the installed lamps. In this case, do the calculation, substituting the value of the coefficient p in the table below:property Type|incandescent Lamp|Halogen lamp|fluorescent svyatetsky room..............30-85....................70-85....................15-22
Living room.....................15-35....................25-35....................7-10
Bedroom......................10-25....................15-17....................4-7
Corridor......................10-20....................10-13....................3-5
Kitchen........................15-40....................30-37....................6-10
Bathroom...............15-30....................22-27....................6-9
Storage room, garage..............12-15....................11-14....................3-5Здесь, to calculate, for example, lighting in the kitchen (area 3 meters square) with the use of fluorescent lamps, take the coefficient of p (average 9) from table, multiply by the kitchen area and if you will be trehrozhkovye lamp, divide by three: 9×3/3 = 9 Watts in each of the three installed in the lamp bulb.