So the plan was to dedicate this afternoon to expanding my knowledge on electric currents and the seemingly complicated business of volts… but alas somehow along the line I instead became fixated with learning all one could ever want to know about copper! What started with a simple search into this metal’s excellent conductivity, sprouted into a beginning-to-end understanding of how copper, and in turn copper wiring, is produced…
So maybe I somewhat wasted a precious afternoon of research, HOWEVER, at least I’ll have a sliver of very specific knowledge should I ever need to influence someone of my extreme cleverness. (Rest easy, below is the abridged version.)
Copper (Cu) is found in ore, (rock containing mineral or metal), which has been mined from the earth in open cut or underground mines. [Open cut mines are those immense pits which are ‘step’ dug into the earth, extending deeper and deeper as the orebodies closest to the surface are depleted.]
The ore is broken, typically through explosives, and brought to the earth’s surface. It is crushed into boulder-sized rocks via a primary crusher, then transported in haul trucks for processing.
There are two types of copper ore, Oxide (less concentrated, but cheaper to process) and Sulfide (less common, but with a higher concentrate of copper).
Oxide is processed in three steps which I will very briefly and rudimentarily touch on. Basically, the first step sees the ore sprayed with a chemical solution that dissolves the copper out of the ore. The pooled copper is then mixed with two ‘unmixable’ liquids, separating any impurities. The copper mixture is then positively charged. Very thin copper starter sheets are dipped into the mixture and left to soak for 10 days which plates the sheets to a thickness of 1 inch. These sheets (cathodes) are now at a purity level of 99.99% and can be used as a raw material.
Sulfide is ground to a fine sand before being added to a liquid to create a slurry. Chemicals are added to the water, making the copper particles waterproof. Air is blown into the solution to create bubbles which rise to the surface with the collected copper. The froth is then skimmed from the top. This is poured into thickeners, which sees the bubbles burst and the copper sink. Excess water is filtered out and the copper is sent to the smelter, a whole system of furnaces. [This part gets pretty long-winded, but if you’re interested I highly recommend this super fun video.]
In short, you end up with copper sheets to be melted and cast into cakes used for plumbing parts and sheeting, or rods used for electrical wiring.
In order to turn the copper into electric wires, there are a few further steps involved.
Copper rods are run through a machine which stretches the metal into a thin strand of wire which is wound onto a large bobbin. Bobbins are loaded into a stranding machine and the ends of two bobbins are ‘cold welded’ together. This machine winds seven wires together, forming a low voltage electric conductor (<1000 volts). These are the wires used to run electricity to your home. The wire is insulated and colour coded with PVC to prevent electric shocks. Multiple wires can be welded and insulated together to create a higher voltage. This somewhat dated but helpful video captures the process.
Why do we use copper in electrical wiring?
Here is where I had to take a side step from copper to briefly brush up on my high school science. I really didn’t enjoy science at school, and honestly cannot remember learning a thing! I’m not sure why I had such difficulty with it, I think I just wrote it off as something I’d never understand. Looking back, it’s a crying shame because it is so darn interesting, especially when one considers…the atom!
What is an atom?
Atoms are the smallest particles that exist. They are the very first building blocks to the make up of everything on earth: plants, tables, humans etc. An atom is the equivalent of a letter in a word, in that it is the smallest unit of a word.
A molecule is the equivalent of a word. So, how you would put together different letters to create different words; different atoms group to create different molecules.
For example: take two Hydrogen atoms and an Oxygen atom (letters) and you get the compound molecule Water (word). Or, take 3 Hydrogens and 1 Nitrogen and you get Ammonia.
Copper is an element, as opposed to a molecule. An element is a substance made entirely of one type of atom. There are 118 elements and these are captured in the periodic table.
An atoms ‘body’ is made up of three particles: electrons (negatively charged), protons (positively charged), and neutrons (neutral). The protons and neutrons group together to form the nucleus, and the electrons ‘hover’ around the nucleus, grouped in orbital shells. An atom is neutral since the total number of electrons is equal to protons. As the protons have an equal amount of draw to the electrons, the electrons can’t ‘run away,’ keeping the atom together.
An atom can have a number of shells, but it is the number of electrons in the outer shell (Valence electrons) that determines the conductivity of an atom.. The lower the number, the higher the conductivity. If there is only one valence electron it will receive most of the energy when two atoms knock together. If there are multiple each electron will only receive a fraction of that energy. Copper atoms contain a single valence electron, making it a perfect conductor.
Creating an Electric Current with Copper:
When exposed to an electric field, copper atoms knock into each other creating a strong repelling reaction. This enables the valence electron to break free from its bond with the atom, allowing it to move around freely. It can now travel through the physical structure of the metal.
To create an electric current, the movement of these free electrons needs to be organised. Batteries or generators can organise electrons to move in one direction, creating a direct current (DC).
Power stations organise electrons by pumping electrons 100 times a second. Instead of moving along in a single direction they remain in place, taking one step forward and one step back, constantly changing direction. This creates an alternating current (AC).
More on this and how it applies to my tiny home next time!