What wire cross-section should be used?

Question

Hello, I am going to power the device with two voltages: 3.3V and 5V. Cable in two sections: 12 meters and 3 meters. What is the minimum cross-section to use? The maximum current is 1A.

vodiczka · Accepted Answer

What voltage drop do you allow on the wires? The cross section of the wire depends on it. If the drop does not exceed 5%, the cable cross-section is 2.5 mm2 for the lower voltage and the 12 m section.

vodiczka · Accepted Answer

All you need is a calculator, e.g. but knowing more about the cross-section selection won't hurt

actin · Answer

Ohm's law is enough. Everything here

rafik73 · Answer

As small as possible, close to 0.

vodiczka · Answer

Then refer to the calculator that I gave in post # 4 and calculate it yourself.
"as small as possible" is not an answer worthy of a technical forum. You need to know what voltage drop will not interfere with the operation of the device and choose the right cable.
When specifying "close to 0", the correct answer to the question what the cross-section should be is: "very large"

rafik73 · Answer

maybe a superconductor? :)

Added after 3 [minutes]:

On Alledrogo, the seller described the cable as follows:
6 x O 0.5 mm Cu Wire

Added after 1 [minutes]:

Second Auction:
CABLE 8 wires x 0.15mm + SCREEN
ROUND, 8x0.15 COMMON SCREEN, COLOR: BLACK
diameter with 5 mm insulation

Added after 22 [minutes]:

At 12 meters, 5V and 1A comes out 2.5mm2. Or:
diameter = square root (area / pi)
diameter = 0.892mm
I need 3 wires so I will use this first product
6 x O 0.5 mm Cu Wire
and I will give two wires for one.
This way, 1mm diameter will come out.

vodiczka · Answer

The wire with a diameter of 0.892 mm has a cross-sectional area of 0.625 mm2 and not 2.5 mm2 A colleague incorrectly transformed the formula into the cross-sectional area (S) of a conductor with a diameter (d) S = ?d2 / 4

rafik73 · Answer

And because I have calculated the circle from the field.

For me it is a bit over the top, for 3.3V 1.5A and 12 meters
a cable with a cross-section of 4mm2 was needed.
1.5 is used for lighting in the house or even for sockets.

Freddy · Answer

The colleague has a special pattern on the circle field?

rafik73 · Answer

area = pi * diameter2

Added after 3 [minutes]:

Sorry, I forgot the diameter is radius * 2

Added after 1 [minutes]:

or:
radius = square root (area / pi)

Added after 1 [minutes]:

I was basing the formula on the radius, not the diameter

ladamaniac · Answer

You see, with a 2000W angle grinder, the wire size is 2.5mmkw. At twelve volts, a starter with twice the power needs 25mmkw. Why?

rafik73 · Answer

Anyway, I will be forced to provide 220V voltage at these 12 meters, then a computer power supply, 3.3V and 5V, connected to the device with a 3-meter cable

ladamaniac · Answer

It will be easier, pay some attention to the places where the wires are connected, with careless installation, as a rule, there are the greatest voltage drops, not on the wires.

rafik73 · Answer

Now it is clear why transmission lines transmit voltage in kV ;) Added after 1 [minutes]: It will destroy the concept a bit, but at least I will sleep well in terms of current efficiency. Added after 3 [minutes]:

ladamaniac · Answer

Nice tables, but for 220V or 230V. 2 volts drop at 230V and the same 2 volts drop at 3.3V, however, is the percentage difference. A colleague of the vodiczka gave the answer in the second post.

rafik73 · Answer

Calculation of the diameter from the cross-sectional area:

diameter = ? (4 * area / ? ;)

Added after 2 [minutes]:

ladamaniac wrote:
Nice tables, but for 220V or 230V.

Maybe it will be useful to someone

ladamaniac wrote:
A colleague of the vodiczka gave the answer in the second post.

I will consider this solution, although I am more inclined to 220V at 12 meters

rafik73 · Answer

I think the topic has been sufficiently covered. Thank you for your help. Subject to be closed.

What wire cross-section should be used?

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