In electrical engineering electrical conductor or a conductor is a type of material that current can flow through it.
As metals have low resistance and high conductance, they are mostly used as electrical conductors.
Why are electrical Conductors important?
Electrical conductors are essential for power transferring and feeding electrical energy to all loads and appliances.
Electrical conductors play an important role in day-to-day life. Starting from the generation stations, electrical conductors are being used to transfer electricity through overhead transmission lines to substations and then to loads and customers. Of course, you are one of tens of millions of customers of electrical energy.
Without electrical conductors, electrical energy will be useless, and the world will sink into complete darkness.
You know what, when you charge your cell phone the USP wire is an electrical conductor. See! I told you, electrical conductors play an important role in day-to-day life.
Uses of Electrical Conductors
The main uses of electrical conductors are, to manufacture electrical devices, machines, and equipment and transfer electrical energy.
Cables and wires are made of electrical conductors such as copper, and they are a basic example of electrical conductor usage.
Cables are used to transfer the electric energy from the powerhouse to your houses, offices, and malls. To glow the light bulbs, we need electrical conductors.
The internet we are using is existing just because of conductors. The internet is a global service. To make it accessible across the globe, the cables made are laid in the deep sea. The mobile phones and laptop we are using have conductors and their applications in them to work.
Conductors are being used to:
- Manufacture electric motors, transformers, generators and all electric equipment.
- Transfer electrical energy between generation stations and customers.
- Wiring homes and buildings.
- Feeding electric loads like motors, fans and lighting bulbs.
Electrical conductor material
Conductors may be metals, electrolyte, metal alloy, or graphite. All these materials allow current to easily pass through them.
Silver is 6% more than copper conductivity, but its not the best choice for conductor material due to its cost. Silver conductors is rarely used in special applications such as satellites
Although aluminum is only 61% of the conductivity of copper, aluminum conductors are the best choice for some applications like transmission lines, because aluminum is lighter in weight and less in cost compared to copper.
What are the characteristics of electrical conductor?
Electrical conductors should conduct electricity. To be a good electrical conductor, a metal should have a high density of free electrons. The greater number of free electrons there, the more will be conductivity.
The metal should have low resistance so that the flow of electrons and holes is easy through the metal.
Metals should not have any energy gap between the conduction band and the valence band of their atoms.
When the electrons are present in the conduction band, they can move freely. The free movement of the valence shell (or band) electrons allows conductivity as they become the agents of the energy transferring from one end of the body to the other.
The electrical conductors also follow the same concept of energy transfer from a higher energy end to the lower energy end. When the electric potential is applied to the body, it provides sufficient energy to the electrons to leave their atom and start roaming in the free space between the atoms.
Electrons do not take a straight path for their flow but a random path is followed with a particular velocity. This velocity is called the Drift Velocity. The metal, to be a conductor should allow the electrons inside it to have a drift velocity.
Otherwise, the electrons will not flow, and electrical energy will not be transferred from the lower energy (potential) to a higher energy (potential). Conclusively, these properties should be in metal to be a conductor.
- Free movement of the electrons inside the metal.
- No external charge should be present inside the conductor, only the internal movement of the electrons should be present on the surface.
- An electric field should not be present inside the conductor. The conductor should have its electric field around itself. The value of the electric field force inside the conductor should be 0.
Copper conductor is being used in many electrical industries and applications, such as electrical motors transformers and generators windings, power cables, small wiring wires and so many applications.
The mix of hardness, strength, and flexibility of copper make it very easy to work with in electrical installations, no special tools are needed for copper wiring.
The measure of how well any material transports electric charges is known as electrical conductivity.
Copper has the best and highest electrical conductivity of all metals except precious metals.
Why is copper a good conductor of electricity?
Copper is one of the best conductors of electricity because it is very good metal, has high metallic properties and a good conductivity. It has high ionization energy as compared to other metals.
Copper is preferred to be used as it is readily available. Copper costs less than other good metals. Silver better than copper, and it’s only 6% better. But silver is much more expensive.
Motors, compressors, and wiring of houses and offices are done using copper due to its good conductivity and low resistance.
Copper offers good electric current flow through itself which makes it better than other metals.
Why is copper not a super-conductor?
Copper is not a super-conductor because it does not follow the properties of super-conductors. Some properties that a conductor like copper must follow to be a super-conductor are:
- Critical Magnetic field
- Expulsion of the magnetic field.
- Infinite Conductivity
- Transition temperature
Copper does not follow these properties. Like if copper has to be a super-conductor, it must follow the critical magnetic field property that states that beyond a particular value of the magnetic field, copper will lose its conductivity. This does not happen with copper.
For the second property satisfaction, copper should not let any magnetic field penetrate itself. While in the case of copper, magnetic fields can penetrate copper easily. For the property of infinite conductivity, copper must offer 0 resistance to the current that flows through itself.
And after a critical temperature, the conductivity of the metal (copper in this case) should be infinite. That too is not possible in the case of copper. The transition property suggests that the metal becomes a superconductor at a particular temperature called transition temperature.
This temperature is achieved by increasing the temperature of the metals not decreasing it. But if we increase the temperature of copper, instead of becoming a superconductor, it melts away. Keeping all these situations in mind, we can say that copper is not a superconductor.
Copper vs aluminum conductors
Copper and aluminum conductors are the most popular electrical conductors, but copper conductivity is better than aluminum, while Aluminum has only 61% of the copper conductivity. But aluminum is less in weight and cost.
So, aluminum conductors are preferred in long distances overhead transmission line. While in electrical motors, generators transformers winding, copper is the best choice because it will reduce the size of the equipment for the same power.
Can copper lugs be used for aluminum cables?
When connecting copper to aluminum cables, galvanic action takes place.
To avoid this galvanic action it is highly advisable to use a special copper aluminum lug, which is well known as a Bi-Metal lug.
The aluminum conductor is widely used because aluminum is considered a good conductive material.
The aluminum conductor is only about 60% of the conductivity of copper conductors and is the most common metal in electric power transmission lines. Aluminum has only 30 percent of the weight of copper wires.
Aluminum conductors are being used in electrical circuits, wiring, and even in high voltage power transmission lines (HV OHTL)
Aluminum wire’s mechanical and chemical properties are its main disadvantages.
Aluminum Conductor ampacity
The ampacity of any conductor is the electrical current amount that conductor can carry, ampacity is related to electrical resistance.
A conductor with lower resistance can carry a larger current, and because copper has lower resistance than aluminum, So a copper conductor with the same cross-sectional area as an aluminum one can carry a larger value of electrical current.
For more information about cable ampacity, read my article here.
Aluminum in electric motors
Copper is the most used wire in motor winding, however, aluminum is used too but not so much.
Why do electric Conductors get hot?
When current passes through any conductor in normal or fault operation, it produces heat.
Increasing the current increases the resistance, and due to more resistance, there will be more heating up of the conductor. Overloading cables, and more current, is the main reason conductors produce more heat. All conductors resist electron flow to some extent generating heat.
Due to the vibration of electrons, conductors get heated up. Electricity is a form of energy and conductors are the agents that pass this energy through themselves.
When an electric current is passed to one end of the conductor, the atoms get energized. This energy ionizes the atoms and atoms lose their valence electrons. These electrons get kinetic energy and start moving in the metal.
This motion is not a proper motion. This motion is a vibration of atoms about their mean position. This vibration makes the conductor hot. When atoms vibrate, the flow of current through the metal is a little suppressed. This phenomenon is called resistance which rises the conductor’s temperature.
So, resistance is the main reason for the conductors getting hot. When many conductors (insulated from each other) are placed with each other and there is no proper airflow and ventilation in that place, the conductors get more heated.
Another reason for conductors getting hot is passing higher magnitude currents through them. Conductors offer more resistance to the higher values of current.
How to reduce overheating of wires?
Choosing the right cable size and applying correction factors to it will suppose to prevent cable overheating. However some common methods to reduce overheating of wires are:
- Use the wire of proper rating. If the wire connections from the source to the load aren’t chosen according to the rating of the load, it will overheat and may burn out. I’ve written a detailed article about Cable sizing, you can read it for more information.
- The wiring should follow the maximum number of conductors in the conduit standards recommendations. Each wire emits a specific amount of thermal energy due to the phenomenon of resistance. When wiring is congested, the heat is accumulated.
- Ambiance can be a factor in heating up wires. So, apply correction factors if the ambient temperature varies from the designed one.
- Corrosion also causes overheating of wires. Corroded wires have more resistance, this resistance sometimes exceeds to a point that it melts off the insulation from the wire.
- Overloading of wires must be avoided at any cost.
- Poor connection leads to overheating of wires because they increase resistance and cause sparking of current. This sparking leads to overheating of the wires.
- If there are loops or coils in the wiring, it causes overheating. When using a temporary cord extension, don’t let the wire in loops.
What causes wires to melt?
Improper and loose connections as well as overload and short circuits cause the wires to melt.
A short circuit has a thermal effect and produces a lot of heat, which results in cables, copper, and insulation, melting.
Multiple extensions of a wire also cause the melting of the wires. It is not something that is not realized directly. But if we observe the extensions of the same wire are actually increasing the load on a wire step by step.
If the total load that is being supplied with electrical energy using the wire becomes greater than the rated value of the wire. The wire will melt.
Why does the human body conduct electricity?
The human body has the electricity of its own. The nervous system needs impulses to conduct messages. These impulses are made of electricity. So, if the human body has electricity of its own, then it can also conduct electricity.
The human body cells have ions. The ions of chlorine, potassium, and sodium. These particles are able to conduct electricity through them.
As the neurons are responsible for the conduction of human current, the external current is also transmitted through them.
Is water a conductor or insulator?
Pure water is an insulator. As pure water is a molecule of Hydrogen combined with an atom of oxygen using hydrogen bonding, there is no free ion or even a free electron in pure water. The structure of water does not allow the current to flow through itself.
Current needs free electrons to pass energy. Water that is H2O does not have any free electrons. It has a very powerful covalent bonding called Hydrogen bonding that does not let it break into atoms or ions easily. Although, pure water is available in laboratories only.
It is prepared by scientists. The water that we drink and use occurs naturally and isn’t only H2O. It has various compounds of calcium, potassium, and other minerals based on where it is present.
These calcium ions can transmit energy through them and also allow the electric current to pass through them. Thus, this water is not an insulator. It becomes a weak conductor that can pass a very small amount of electric current through itself.
Conclusively, we can state that water in its pure form does not conduct electricity but naturally occurring water conducts the current that can be felt when someone comes in contact with it.
Can distilled water conduct electricity?
NO! Distilled water is an insulator. Distilled water can not conduct electricity. Distilled water is purified water that does not have any minerals or ions to conduct electricity.
When naturally occurring, water is passed through the process of removal of ions and minerals, and the conductive elements of water are actually removed.
These minerals and ions were actually the conductive agents in the water. When they are removed, water becomes an insulator.
How to increase the conductivity of water?
There are several methods of increasing the conductivity of the water. Some of them are discussed below.
Increasing the temperature:
The increase in temperature makes the intermolecular forces of water weaker. Weaker forces let the electron leave the valence shells and thus these electrons play part in the transfer of electrical energy.
By adding the ions or a compound that ionizes in the water, we can increase the conductivity of water. For a simple example, we may consider adding non-iodized table salt to the water. When pure salt NaCl is added to water, it ionizes into Na+ and Cl– ions. These ions have a high tendency to conduct electricity.
Adding a small amount of acid to the water also increases the conductivity of water. Water ionizes the acid and this process is called Electrolysis. Through the process, water transforms into an electrolyte. Electrolytes are highly conductive.
Is stainless steel a good conductor of electricity?
Stainless steel is an electrical conductor. But it is not a very efficient electric conductor.
The resistivity of stainless steel is about 40 times more than that of copper.
Although, stainless steel is an alloy of two metals i.e., steel and nickel. But stainless steel does not conduct as good as well as steel does.
However, most of the car antennas we see on the roof of the cars are stainless steel plated. It does not rust easily. It has a very good shining appeal that looks very good to the viewer.
But due to the higher value of its specific resistance i.e., 6.7×10-7 ohm-meter it is not considered a reliable conductor for wiring and other electrical components.
Is glass an electrical conductor or an Insulator?
Glass is an insulator. Glass in its normal state (solid state), at room temperature is a very good insulator. But when heated to a very high temperature it can conduct electric current through itself.
The reason is in solid-state, room-temperature glass has a very good, fixed structure due to strongly bonded compounds. When glass is heated, it melts after a certain temperature and starts conduction. When the glass melts it loses its solid structure and becomes fluid.
This fluid has weaker intermolecular forces and has free electrons in it that allow conduction. Glass does not melt until it is heated from 1300 degrees Celsius to 1600 degrees Celsius. The resistivity of glass is 108 times the resistivity of copper. This makes it impossible to conduct the current using glass in normal conditions.
Is plastic an electric conductor or an Insulator?
Plastic is an insulator. The structure of plastic consists of strongly bonded atoms. These atoms have strong intermolecular forces that are not easy to be broken. A very high amount of energy is required to break these intermolecular forces.
Yet there are some plastics that can conduct electricity. The polar polymers have a tendency to conduct current through them. As polar polymers have positive and negative poles, electricity is passed through the polar polymer.
Do electrical conductors conduct heat?
Yes. Electrical conductors conduct heat very effectively. Almost, all electrical conductors are metal. Metals are the best Thermal conductors. (Materials that can conduct heat are called thermal conductors).
The basic condition for the conductors to be conductive is to transfer the heat/ electricity from one end of their body to the other end. In doing so, they use their free electrons.
When heat is applied at one end of the electrical conductors, the free electrons get energized and pass the energy to their adjacent electrons.
Why is humid air a better electrical conductor?
Humid air is a better electrical conductor because it has moisture in it.
When it is raining or snowing, the air gets moist. The presence of water vapors in the air increase and the air becomes conductive.
Now we have to realize that this conductivity is effective for the static charge. It means that if a body has a static charge present on it and is placed in humid air, it is more likely for the body to lose its static charge now.
Static charge is developed on a body due to the process of induction. When a body is rubbed over another body both bodies get charged oppositely.
Now if we place these bodies outside and check if they are charged or not. We will find out that there will be no charge on them because the humid air takes the charge from the body and spreads the charge on itself. The humid air conducts the static charge.