DC voltage drop on the long lines

Comfort in the house should be planned at the construction stage. You need to properly design all engineering networks, because it is a guarantee of their reliable operation and your peace of mind for many years.
This primarily applies to the planning of the electrical network of the property. You need to plan in detail which devices will be used, where they will be placed, what is their capacity. Based on this information, you can choose the parameters of power cables, foremost - the cross-section of the conductor.


There are many tables and calculation methods for choosing the right cable cross-section.
For example:


The simplest formula, which is well suited for household networks - 1 mm2 is enough for a current of 8-10A. It is clear that it is necessary to take into account not only the total current consumption of devices that will be used, but also to make a margin for the future. This calculation is extremely important, not only for the stable operation of the equipment, but also for your safety. After all, if the cross-section of the cable is too small - when the current flows, the cable will heat up, which can lead to insulation damage, short circuit and fire.
When designing a power grid, it is necessary to keep in mind another important parameter. Namely - the voltage drop on long lines, which is caused by the electrical resistance of the cable. To calculate this parameter, use the formula:

ΔU = 2ρLI / S

whereρ - specific resistance of copper, which is 0.0175 Ohm * mm.sq / mL - line length, mI - current, AS - cross-section, mm2

You can also use specialized online calculators. According to various regulations, it is permissible to have a drop of the voltage at the end of the cable within 3-5% of the input voltage.
This requirement is especially relevant in the case of connecting low-voltage devices with high current consumption. For example, LED strips. After all, the drop in voltage of 2V for devices with a supply voltage of 220V will be less than 1%, and for a strip designed for 12V, it will be almost 17%. Which, in turn, will cause a drop in brightness of more than 2 times. Moreover, if a full-colour RGB strip is used, uneven brightness of coloured LEDs will be observed. When the supply voltage of such a strip is reduced, the brightness of the blue LEDs first decreases, and when the voltage is further reduced, the brightness of the green LEDs also loses. That is, if you set the white colour of the glow of the tape, then when the supply voltage decreases, it will change to yellow and then to red.


To avoid such situations, in addition to the correct selection of the cross-section of the cables, we recommend the use of LED strips with a supply voltage of 24V. In addition to the obvious advantages of this choice, there is another. The outputs of the Atom series controllers have limitations on the connection of current loads. This means that twice as much powerful LED strip can be connected to one output as would be possible with a supply voltage of 12V.
In any case, keep in mind that the actual cross-sectional area of the cable is important, not the one stated by the manufacturer. And trying to save too much by using smaller cables or using aluminium conductors can lead to unforeseen financial costs in the future to replace some networks and additional repairs in the room.

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