When the network is three-phase, the formula will look like this:
I=P/(1.73×U×cosφ), where P is the electrical power of the load, W;
- U — actual voltage in the network, V;
- cosφ — power factor.
Next, all currents are summ up and the cable cross-section by current must be select using the table values.
It should be not that the values of the table quantities fantuan data depend on the conditions of the conductor installation. The power and current loads will be significantly greater when installing open electrical wiring than if the wiring is install in a pipe.
It is recommend to multiply the resulting total value of currents by 1.5 times for reserve, since over time more powerful electrical appliances may be purchas for the apartment.
Calculation of cable cross-section by length.
You can also calculate the cable cross-section by length. The essence of such calculations is that each of the conductors has its own resistance, which contributes to current losses with url of the website page that uses a subdomain for the samara region url of the website page that uses a subdomain for the samara region length. It is necessary to choose a conductor with larger cores if the loss value exces 5%.
The calculations are as follows:
- The total power of all electrical appliances and the current strength are calculat.
- Then the resistance of the electrical wiring is calculat italy numbers the formula: specific resistance of the conductor (p) * length (in meters).
- It is necessary to divide the resulting value by the select cable cross-section:
R=(p*L)/S, where p is a tabular value
It should be not that the length of the current passage should be multipli by 2 times, since initially the current goes along one wire and returns back along the other.
- The voltage loss is calculat: the current strength is multipli by the calculat resistance.
- Next, the amount of loss is determin: voltage loss is divid by the network voltage and multipli by 100%.
- The final number is analyz. If the obtain value is less than 5%, then the select cross-section of the core can be left, but if it is more, then it is necessary to select a “thicker” conductor.
Online assistant for home master
The correct selection of an electric cable is important to ensure a sufficient level of safety, to use the cable cost-effectively and to fully utilize all the capabilities of the cable. A properly calculat cross-section must be able to constantly operate under full load, without damage, withstand short circuits in the network, provide a load with the appropriate voltage (without excessive voltage drop) and ensure the operability of protective devices during grounding insufficiency. This is why a scrupulous and accurate calculation of the cable cross-section by power is made, which can be done quite quickly today using our online calculator.
Calculations are made individually according to the formula for calculating the cable cross-section separately for each power cable for which a certain cross-section nes to be select, or for a group of cables with similar characteristics. All methods for determining cable sizes to one degree or another follow the basic 6 points:
- Collecting data about the cable, its installation conditions, the load it will carry, etc.
- Determining the minimum cable size bas on current calculation
- Determination of minimum cable size bas on voltage drop consideration
- Determination of minimum cable size bas on short circuit temperature ris
- etermining the minimum cable size bas on loop impance when there is a lack of grounding
- Selection of the largest cable dimensions bas on calculations in points 2, 3, 4 and 5
