Is there a reason why wires are solid copper or strands of copper?

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I noticed that wirings have different kinds wires inside the rubber coating. Does it make any difference in terms of transferring electricity or being solid or strands have its own purposes?

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Solid wire conducts better because as less surface area and in the same space has more copper. It’s also cheaper to manufacture and it’s a little bit more rigid for whatever wire needs to stay in place.

Stranded wires are flexible The thin wires can easily bend together. It’s also less likely to break if you bend the wire back and forth a thousand times. If you do that with a solid wire it’s more likely to break.

If you want a cheaper to manufacture wire that’s going to sit in the walls of your house and not have as much dissipation of energy off as heat then solid wire is best.

If you have a cord that’s going to be going to a lamp that’s going to be moved around a whole lot back and forth then stranded is better for you

Solid is cheaper, stranded is more flexible. Solid is used more for permanent, non-moving fixtures, stranded for movable cords. They both conduct the same.

Depends on the application. If you’re talking about Ethernet cables, the following are some typical guidelines:

Solid core cables are better used in infrastructure, where the cable usually isn’t moved around much and the wire is less likely to break. Solid wires are typically terminated on punch blocks. Solid core cables can transmit longer distances and suffer from fewer issues when used with Power Over Ethernet devices (sending data and power over different wires within the same cable).

Stranded core cables are less brittle, and are better for patch cables. They are typically terminated using an RJ45 or similar connector.

There is actually a difference in how the electricity travels in the wire itself, and it depends on the voltage and frequency of the electricity being carried. Sadly I don’t know the details, I could never keep it straight.

The other answers are 50% of the story (low cost with solid core vs need to flex with stranded) but there’s another detail they missed: signal type. For pure power, high current, more copper is better, so you want thick solid core. As you go higher frequency though, for things like data, the signal actually doesn’t travel in the core of the wire but rather on a thin part of the surface (called the skin effect). Because the signal only travels on the surface, you really just don’t need more wire, so you make it super thin and save money on the copper. You may be familiar with speaker wire like this.

Now here is the kicker, variable speed motors or other things that both have fast changing signals AND need high currents need an extra little detail. Just using stranded wire won’t solve the skin effect on it’s own because wires touching each other will act like one bigger wire (good for current, bad for skin effect) so you have to insulate each wire individually so now you can have a bundle of wires, each conducting current only on the surface, but still provide a path for a large current to flow.

Think of stranded wires as long ponytail. while a solid copper conductor as a styrofoam float (for swimming assistance)

The stranded wire is a lot more flexible (like the ponytail). Solid wire is not so flexible (like the Styrofoam float go swimming assistance).

To the rest who believe it has no effect on current carrying capacity:
there is a difference between current carrying capacity for stranded cable and solid cables for AC current. For DC not at all.

Alternating current travels via the skin effect and is highly dependent on the available surface area. This isn’t a big deal at very low voltage is like 230 VAC / 110VAC. butbut at high-voltage (say 1kv and above) it has detrimental transmission effects by virtue of increase in resistance.

DC is volumetric in nature. And will do better in solid conductor va stranded conductor (at very high voltages)

Stranded wires for movable applications like anything you plug into an outlet e.g. vacuum cleaner, Kitchen blender, extension cords etc.

Solid wires for immovable applications like anything wall mounted. There is no law or standard that requires you to use solid wires at all. They are just cheaper to make, yield more copper per volume, easier to organize, and the insulation material isn’t as stressed much as it doesn’t move.

I’m not expert but solid core is harder to manage. A small nick in a solid core cable means u have to restrip a new part of the cable and discard the nicked part. Stranded allows for more leeway cause if u nick one of the strands it’s pretty much the same.

There is a reason large power cables, 500, 750, 1000 MCM etc. are stranded. It is because they can carry more current than the equivalent size solid cable.