Three way switch

Wiring Three Way Switch

 

Three-way switches control lights and receptacles from two points: for example, a light in a hallway that can be operated from the first floor and second floor. Or, a light in a garage that can be turned on/off from the garage and the kitchen or pantry, etc.

How to wire a 3-Way switch. Wiring a 3-way switch is a little more tricky than wiring a 2-way switch. First of all we need to go over a little basic terminology on switches.  It should also help in understanding the functions of each type of switch. When wiring a 3-way switch circuit, What were doing is simply controlling the power flow (Switching off/on) to the load (a light, lamp, outlet, ceiling fan etc..) from 2 different locations. a couple examples would be:
At each end of a hallway.
At the top & bottom of a stairway.
Each 3-way switch in these examples are controlling the power source to the same load. When wiring a 3-way switch circuit, we will be using a 3-wire cable known as romex coming from the source (such as the breaker box). Then a 4-wire cable going between the two 3-way switches and then a 3-wire cable going from the switches to the load. The 3-wire cable consist of a black wire, a white wire and a bare copper wire, while the 4-wire cable has an added red wire which is hot as well. See Below…

3-Wire Cable
Black wire = Power or Hot wire
White wire = Neutral
Bare copper = Ground

When wiring a 3-way switch circuit, all we want to do is to control the black wire (hot wire) to turn on and off the load from 2 different locations. The diagram below will give you a better understanding how this circuit is wired.
3-Way Switch Wiring Diagram
3-Way Switch Terminals

Notice that there is a 3-conductor cable coming into the first box, then a 4-conductor cable going from left box to right box, then a 3-conductor cable going from the right box to the load.
Now for wiring, lets assume you’re looking at the switch just like it shows.

The Left Box:
The lower left screw is the common and gets the black wire from the source (3-cond). The upper left screw gets the black wire from the right box (4-cond). The upper right screw gets the red wire from the right box (4-cond). The white wires tie together with a wire nut. The bare copper wires tie together with a wire nut. Be sure to attach a bare copper wire to the green screw on the switch.

The Right Box:
The lower left screw is the common and gets the black wire from the load (3-cond). The upper left screw gets the red wire from the left box (4-cond). The upper right screw gets the black wire from the left box (4-cond). The white wires tie together with a wire nut. The bare copper wires tie together with a wire nut. Be sure to attach a bare copper wire to the green screw on the switch.

 

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Electrical Conductors and Insulators

What is Conductors and Insulators?

In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.

The behavior of an object that has been charged is dependent upon whether the object is made of a conductive or a nonconductive material. Conductors are materials that permit electrons to flow freely from particle to particle. An object made of a conducting material will permit charge to be transferred across the entire surface of the object. If charge is transferred to the object at a given location, that charge is quickly distributed across the entire surface of the object. The distribution of charge is the result of electron movement. Since conductors allow for electrons to be transported from particle to particle, a charged object will always distribute its charge until the overall repulsive forces between excess electrons is minimized. If a charged conductor is touched to another object, the conductor can even transfer its charge to that object. The transfer of charge between objects occurs more readily if the second object is made of a conducting material. Conductors allow for charge transfer through the free movement of electrons.

In contrast to conductors, insulators are materials that impede the free flow of electrons from atom to atom and molecule to molecule. If charge is transferred to an insulator at a given location, the excess charge will remain at the initial location of charging. The particles of the insulator do not permit the free flow of electrons; subsequently charge is seldom distributed evenly across the surface of an insulator.

While insulators are not useful for transferring charge, they do serve a critical role in electrostatic experiments and demonstrations. Conductive objects are often mounted upon insulating objects. This arrangement of a conductor on top of an insulator prevents charge from being transferred from the conductive object to its surroundings. This arrangement also allows for a student (or teacher) to manipulate a conducting object without touching it. The insulator serves as a handle for moving the conductor around on top of a lab table. If charging experiments are performed with aluminum pop cans, then the cans should be mounted on top of Styrofoam cups. The cups serve as insulators, preventing the pop cans from discharging their charge. The cups also serve as handles when it becomes necessary to move the cans around on the table.

Examples of Conductors and Insulators
Examples of conductors include metals, aqueous solutions of salts (i.e., ionic compounds dissolved in water), graphite, and the human body. Examples of insulators include plastics, Styrofoam, paper, rubber, glass and dry air. The division of materials into the categories of conductors and insulators is a somewhat artificial division. It is more appropriate to think of materials as being placed somewhere along a continuum. Those materials that are super conductive (known as superconductors) would be placed at on end and the least conductive materials (best insulators) would be placed at the other end. Metals would be placed near the most conductive end and glass would be placed on the opposite end of the continuum. The conductivity of a metal might be as much as a million trillion times greater than that of glass.

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Electrical Current

What is electric current?

Electric current is defined as the rate at which charge flows through a surface (the cross section of a wire, for example). Despite referring to many different things, the word current is often used by itself instead of the longer, more formal “electric current”. The adjective “electrical” is implied by the context of the situation being described. The phrase “current through a toaster” surely refers to the flow of electrons through the heating element and not the flow of slices of bread through the slots.

Conventional Current Direction
The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions.

Ben Franklin, who conducted extensive scientific studies in both static and current electricity, envisioned positive charges as the carriers of charge. As such, an early convention for the direction of an electric current was established to be in the direction that positive charges would move. The convention has stuck and is still used today. The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction. Knowing that the actual charge carriers in wires are negatively charged electrons may make this convention seem a bit odd and outdated. Nonetheless, it is the convention that is used worldwide and one that a student of physics can easily become accustomed to.

Current versus Drift Speed
Current has to do with the number of coulombs of charge that pass a point in the circuit per unit of time. Because of its definition, it is often confused with the quantity drift speed. Drift speed refers to the average distance traveled by a charge carrier per unit of time. Like the speed of any object, the drift speed of an electron moving through a wire is the distance to time ratio. The path of a typical electron through a wire could be described as a rather chaotic, zigzag path characterized by collisions with fixed atoms. Each collision results in a change in direction of the electron. Yet because of collisions with atoms in the solid network of the metal conductor, there are two steps backwards for every three steps forward. With an electric potential established across the two ends of the circuit, the electron continues to migrate forward. Progress is always made towards the positive terminal. Yet the overall effect of the countless collisions and the high between-collision speeds is that the overall drift speed of an electron in a circuit is abnormally low. A typical drift speed might be 1 meter per hour. That is slow!

One might then ask: How can there by a current on the order of 1 or 2 ampere in a circuit if the drift speed is only about 1 meter per hour? The answer is: there are many, many charge carriers moving at once throughout the whole length of the circuit. Current is the rate at which charge crosses a point on a circuit. A high current is the result of several coulombs of charge crossing over a cross section of a wire on a circuit. If the charge carriers are densely packed into the wire, then there does not have to be a high speed to have a high current. That is, the charge carriers do not have to travel a long distance in a second, there just has to be a lot of them passing through the cross section. Current does not have to do with how far charges move in a second but rather with how many charges pass through a cross section of wire on a circuit.

To illustrate how densely packed the charge carriers are, we will consider a typical wire found in household lighting circuits – a 14-gauge copper wire. In a 0.01 cm-long (very thin) cross-sectional slice of this wire, there would be as many as 3.51 x 1020 copper atoms. Each copper atom has 29 electrons; it would be unlikely that even the 11 valence electrons would be in motion as charge carriers at once. If we assume that each copper atom contributes just a single electron, then there would be as much as 56 coulombs of charge within a thin 0.01-cm length of the wire. With that much mobile charge within such a small space, a small drift speed could lead to a very large current.

To further illustrate this distinction between drift speed and current, consider this racing analogy. Suppose that there was a very large turtle race with millions and millions of turtles on a very wide race track. Turtles do not move very fast – they have a very low drift speed. Suppose that the race was rather short – say 1 meter in length – and that a large percentage of the turtles reached the finish line at the same time – 30 minutes after the start of the race. In such a case, the current would be very large – with millions of turtles passing a point in a short amount of time. In this analogy, speed has to do with how far the turtles move in a certain amount of time; and current has to do with how many turtles cross the finish line in a certain amount of time.

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Voltage Drop

What is the meaning of voltage drop?

Voltage drop is defined as the amount of voltage loss that occurs through all or part of a circuit due to impedance. A common analogy used to explain voltage, current and voltage drop is a garden hose. Voltage is analogous to the water pressure supplied to the hose.

Allowable Voltage Drop
The voltage drop in the main power wires from the generation source or the battery to the bus should not exceed 2 percent of the regulated voltage when the generator is carrying rated current or the battery is being discharged at the 5-minute rate.
It’s caused by wire resistance leading up to a load. The voltage dropped at DC is the Ohm’s law V = IR. In fact it is sometimes called “IR drop.” … The device feels like it’s connected to a source that has no internal resistance.

Why is there a voltage drop across a resistor?
The larger the resistor, the more energy used by that resistor, and the bigger the voltage drop across that resistor. Ohm’s Law can be used to verify voltage drop. In a DC circuit, voltage equals current multiplied by resistance. .

Is potential difference and voltage drop the same thing?
Voltage is the potential difference between the source & any point in the circuit. Voltage drop means, amount of voltage by which voltage across load resistor is less then the source voltage. there is voltage drop in wire connected to the positive terminal of the source to load resistor.

How do you figure out voltage drop?
Voltage drop of the circuit conductors can be determined by multiplying the current of the circuit by the total resistance of the circuit conductors: VD = I x R. “I” is equal to the load in amperes and ”R” is equal to the resistance of the conductor as listed in Chapter 9, Table 8 for direct current circuit, or in …

How do you know if your wiring will provide a reasonable efficiency of operation?

The National Electrical Code, 210-19(a) (FPN 4) and 215-2 (b) (FPN 3), recommends 5% voltage drop for feeder circuits and 3% for branch circuits. Let’s work some examples, using the equations in the sidebar (right). Our examples use uncoated copper wire in steel conduit, for 480V branch circuits; we’ll use NEC Table 9’s power factor column.

Example 1: Determine voltage drop Run a No. 10 stranded wire 200 ft at 20A. Per Table 9, our “ohms to neutral per 1,000 ft” is 1.1 ohms. To complete the numerator, multiply as follows: (2 x 0.866) x 200 ft x 1.1 ohms x 20A = 7620.8 Dividing 7621 by 1000 ft gives a voltage drop of 7.7V. This drop is acceptable for our 480V circuit. A No. 12 would drop 11.8V. Boost the length to 500 ft, and that No. 10 drops 18V; the No. 12 drops 29V.

Example 2: Determine wire size Run a stranded copper wire 200 ft at 20A. You can find the wire size by algebraically altering the first equation, or you can use the following method. To complete the numerator, multiply as follows: 1.73 x 212.9 ohms x 200 ft x 20A = 89371.2 Dividing the 89371.2 by the acceptable voltage drop of 14.4V gives you 6207 circular mils. NEC Table 8 shows that a No. 12 wire satisfies the voltage drop recommendation.

Example 3: Determine wire length Run a stranded copper No. 10 wire for a 20A circuit. To complete the numerator, multiply as follows: 1000 x 14.4V = 14400 To complete the denominator, multiply as follows: (2 x 0.866) x 1.1ohms x 20A = 38.104 Finally, divide the numerator by the denominator, as follows: 14400 / 38.1044377 ft If you ran the No. 12 wire for the same circuit, you could run it 244 ft.

Example 4: Determine maximum load Run a stranded copper No. 10 wire for a 200 ft circuit. To complete the numerator, multiply as follows: 1000 x 14.4V = 14400 To complete the denominator, multiply as follows: (2 x 0.866) x 1.1 ohms x 200 ft = 381.04 Finally, divide the numerator by the denominator, as follows: 14400 / 381.04437A This circuit could handle 37A on each phase conductor. A 200 ft No. 2 could handle 24A.

* The number “0.866” is for 3-phase only. It converts the number “2” to “1.732” (the square root of 3). For single-phase circuits, don’t use the “0.866” in the calculations. * “CM”denotes wire size in circular mils, as shown in Table 8. * To calculate wire size, use 12.9 as your K for copper and 21.2 as your K for aluminum. * “L” is the one-way wire length in ft. * “R” is the resistance per 1,000 ft. Use NEC Table 9 for AC wiring. If you have non-linear loads, use the column that helps account for power factor.

Equation 1: Calculating the actual Voltage Drop in volts Volts Dropped = (2 x 0.866) x L x R x Amps/1000

Equation 2: Calculating the Wire Size in circular mils CM = 2 x K x L x Amps/Acceptable Voltage Drop Alternatively, you can algebraically manipulate Equation 1 to: R410002Acceptable Voltage Drop/1.732 x L x Amps and then look up the wire size according to its AC resistance.

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Transformer

what is inductor?

An inductor is a passive electronic component that stores energy in the form of a magnetic field. In its simplest form, an inductor consists of a wire loop or coil. The inductance is directly proportional to the number of turns in the coil. Inductance also depends on the radius of the coil and on the type of material around which the coil is wound.

This produces a relationship between the direction of this magnetic flux which is circulating around the conductor and the direction of the current flowing through the same conductor resulting in a well known relationship between current and magnetic flux direction called, “Fleming’s Right Hand Rule”.

But there is also another important property relating to a wound coil that also exists, which is that a secondary voltage is induced into the same coil by the movement of the magnetic flux as it opposes or resists any changes in the electrical current flowing

In its most basic form, an Inductor is nothing more than a coil of wire wound around a central core. For most coils the current, ( i ) flowing through the coil produces a magnetic flux, (  ) around it that is proportional to this flow of electrical current.

The Inductor, also called a choke, is another passive type electrical component which is just a coil of wire that is designed to take advantage of this relationship by inducing a magnetic field in itself or in the core as a result of the current passing through the coil. This results in a much stronger magnetic field than one that would be produced by a simple coil of wire.

Inductors are formed with wire tightly wrapped around a solid central core which can be either a straight cylindrical rod or a continuous loop or ring to concentrate their magnetic flux.

The schematic symbol for a inductor is that of a coil of wire so therefore, a coil of wire can also be called an Inductor. Inductors usually are categorised according to the type of inner core they are wound around, for example, hollow core (free air), solid iron core or soft ferrite core with the different core types being distinguished by adding continuous or dotted parallel lines next to the wire coil as shown below.

Inductor Symbols

inductor construction

The current, i that flows through an inductor produces a magnetic flux that is proportional to it. But unlike a Capacitor which oppose a change of voltage across their plates, an inductor opposes the rate of change of current flowing through it due to the build up of self-induced energy within its magnetic field.

In other words, inductors resist or oppose changes of current but will easily pass a steady state DC current. This ability of an inductor to resist changes in current and which also relates current, i with its magnetic flux linkage, as a constant of proportionality is called Inductance which is given the symbol L with units of Henry, (H) after Joseph Henry.

Because the Henry is a relatively large unit of inductance in its own right, for the smaller inductors sub-units of the Henry are used to denote its value. For example:

Inductance Prefixes

Prefix Symbol Multiplier Power of Ten
milli m 1/1,000 10-3
micro µ 1/1,000,000 10-6
nano n 1/1,000,000,000 10-9

So to display the sub-units of the Henry we would use as an example:

  • 1mH = 1 milli-Henry  –  which is equal to one thousandths (1/1000) of an Henry.
  • 100uH = 100 micro-Henries  –  which is equal to 100 millionth’s (1/1,000,000) of a Henry.

Inductors or coils are very common in electrical circuits and there are many factors which determine the inductance of a coil such as the shape of the coil, the number of turns of the insulated wire, the number of layers of wire, the spacing between the turns, the permeability of the core material, the size or cross-sectional area of the core etc, to name a few.

An inductor coil has a central core area, ( A ) with a constant number of turns of wire per unit length, ( l ). So if a coil of N turns is linked by an amount of magnetic flux, Φ then the coil has a flux linkage of and any current, ( i ) that flows through the coil will produce an induced magnetic flux in the opposite direction to the flow of current. Then according to Faraday’s Law, any change in this magnetic flux linkage produces a self-induced voltage in the single coil of:

faradays law of self induced emf

  • Where:
  •     N is the number of turns
  •     A is the cross-sectional Area in m2
  •     Φ is the amount of flux in Webers
  •     μ is the Permeability of the core material
  •     l is the Length of the coil in meters
  •     di/dt is the Currents rate of change in amps/second

A time varying magnetic field induces a voltage that is proportional to the rate of change of the current producing it with a positive value indicating an increase in emf and a negative value indicating a decrease in emf. The equation relating this self-induced voltage, current and inductance can be found by substituting the μN2A / l with L denoting the constant of proportionality called the Inductance of the coil.

The relation between the flux in the inductor and the current flowing through the inductor is given as: Φ = Li. As an inductor consists of a coil of conducting wire, this then reduces the above equation to give the self-induced emf, sometimes called the back emf induced in the coil too:

The back emf Generated by an Inductor

back emf of an inductor

Where: L is the self-inductance and di/dt the rate of current change.

an inductor coilInductor Coil

So from this equation we can say that the “self-induced emf = inductance x rate of current change” and a circuit has an inductance of one Henry will have an emf of one volt induced in the circuit when the current flowing through the circuit changes at a rate of one ampere per second.

One important point to note about the above equation. It only relates the emf produced across the inductor to changes in current because if the flow of inductor current is constant and not changing such as in a steady state DC current, then the induced emf voltage will be zero because the instantaneous rate of current change is zero, di/dt = 0.

With a steady state DC current flowing through the inductor and therefore zero induced voltage across it, the inductor acts as a short circuit equal to a piece of wire, or at the very least a very low value resistance. In other words, the opposition to the flow of current offered by an inductor is very different between AC and DC circuits.

The Time Constant of an Inductor

We now know that the current can not change instantaneously in an inductor because for this to occur, the current would need to change by a finite amount in zero time which would result in the rate of current change being infinite, di/dt = , making the induced emf infinite as well and infinite voltages do no exist. However, if the current flowing through an inductor changes very rapidly, such as with the operation of a switch, high voltages can be induced across the inductors coil.

inductor circuit

Consider the circuit of the inductor on the right. With the switch, ( S1 ) open, no current flows through the inductor coil. As no current flows through the inductor, the rate of change of current (di/dt) in the coil will be zero. If the rate of change of current is zero there is no self-induced emf, ( VL = 0 ) within the inductor coil.

If we now close the switch (t = 0), a current will flow through the circuit and slowly rise to its maximum value at a rate determined by the inductance of the inductor. This rate of current flowing through the inductor multiplied by the inductors inductance in Henry’s, results in some fixed value self-induced emf being produced across the coil as determined by Faraday’s equation above, VL = Ldi/dt.

This self-induced emf across the inductors coil, ( VL ) fights against the applied voltage until the current reaches its maximum value and a steady state condition is reached. The current which now flows through the coil is determined only by the DC or “pure” resistance of the coils windings as the reactance value of the coil has decreased to zero because the rate of change of current (di/dt) is zero in steady state. In other words, only the coils DC resistance now exists to oppose the flow of current.

Likewise, if switch, (S1) is opened, the current flowing through the coil will start to fall but the inductor will again fight against this change and try to keep the current flowing at its previous value by inducing a voltage in the other direction. The slope of the fall will be negative and related to the inductance of the coil as shown below.

Current and Voltage in an Inductor

current in an inductor

How much induced voltage will be produced by the inductor depends upon the rate of current change.  “the direction of an induced emf is such that it will always opposes the change that is causing it”. In other words, an induced emf will always OPPOSE the motion or change which started the induced emf in the first place.

So with a decreasing current the voltage polarity will be acting as a source and with an increasing current the voltage polarity will be acting as a load. So for the same rate of current change through the coil, either increasing or decreasing the magnitude of the induced emf will be the same.

Inductor Example

A steady state direct current of 4 ampere passes through a solenoid coil of 0.5H. What would be the back emf voltage induced in the coil if the switch in the above circuit was opened for 10mS and the current flowing through the coil dropped to zero ampere.

induced voltage in an inductor

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Electrical Symbols

The importance of electrical symbols

Electric Symbol Circuit

An electrical symbol is a pictogram used to represent various electronic and electrical devices (such as wires, batteries, resistors, and transistors) in a schematic diagram of an electrical or electronic circuit.

Electrical symbols and electronic circuit symbols are often used for drawing circuits.These symbols represent electronic devices and components. Edraw Max was the one who demonstrated standard electrical symbols, that had recognizable, industrial standard and even vector-based for electrical schematic diagrams. These helps you to design circuit instantly.

The Electrical Symbols and Their Meanings

 

Earth electrode is a metal plate, water pipe, or other conductor of electricity partially buried in the earth so as to constitute and provide a reliable conductive path to the ground

Cell is a device containing electrodes immersed in an electrolyte, used for generating current or for electrolysis.

Battery is a container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power.

Source is a part of a field-effect transistor from which carriers flow into the inter-electrode channel.

Ideal source includes ideal voltage source and ideal current source. An ideal source is a theoretical concept of an electric current or voltage supply (such as a battery) that has no losses and is a perfect voltage or current supply. Ideal sources are used for analytical purposes only since they cannot occur in nature.

Resistor is a device having resistance to the passage of an electric current.

Capacitor is a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator.

Antenna is an electrical device which converts electric power into radio waves, and vice versa.

Some most commonly-used basic electrical symbols used in schematic diagrams are shown below:

Most Commonly Used Basic Electrical Symbols

Let we take a look at how to use the basic electrical symbols to provide a schematic diagram of the circuit and its components. Example one: three D-cells are placed in a battery pack to power a circuit containing three light bulbs. Each light bulb is represented by its own individual resistor symbol. Straight lines have been used to connect the two terminals of the battery to the resistors and the resistors to each other.

 

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Series and Parallel Circuit

The Series and Parallel Circuits

Circuits consisting of just one battery and one load resistance are very simple to analyze, but they are not often found in practical applications. Usually, we find circuits where more than two components are connected together.

There are two basic ways in which to connect more than two circuit components: series and parallel. First, an example of a series circuit:

Here, we have three resistors (labeled R1, R2, and R3), connected in a long chain from one terminal of the battery to the other. (It should be noted that the subscript labeling—those little numbers to the lower-right of the letter “R”—are unrelated to the resistor values in ohms. They serve only to identify one resistor from another.) The defining characteristic of a series circuit is that there is only one path for electrons to flow. In this circuit the electrons flow in a counter-clockwise direction, from point 4 to point 3 to point 2 to point 1 and back around to 4.

Now, let’s look at the other type of circuit, a parallel configuration:

Again, we have three resistors, but this time they form more than one continuous path for electrons to flow. There’s one path from 8 to 7 to 2 to 1 and back to 8 again. There’s another from 8 to 7 to 6 to 3 to 2 to 1 and back to 8 again. And then there’s a third path from 8 to 7 to 6 to 5 to 4 to 3 to 2 to 1 and back to 8 again. Each individual path (through R1, R2, and R3) is called a branch.

The defining characteristic of a parallel circuit is that all components are connected between the same set of electrically common points. Looking at the schematic diagram, we see that points 1, 2, 3, and 4 are all electrically common. So are points 8, 7, 6, and 5. Note that all resistors as well as the battery are connected between these two sets of points.

And, of course, the complexity doesn’t stop at simple series and parallel either! We can have circuits that are a combination of series and parallel, too:

In this circuit, we have two loops for electrons to flow through: one from 6 to 5 to 2 to 1 and back to 6 again, and another from 6 to 5 to 4 to 3 to 2 to 1 and back to 6 again. Notice how both current paths go through R1(from point 2 to point 1). In this configuration, we’d say that R2 and R3 are in parallel with each other, while R1 is in series with the parallel combination of R2 and R3.

This is just a preview of things to come. Don’t worry! We’ll explore all these circuit configurations in detail, one at a time!

 

The basic idea of a “series” connection is that components are connected end-to-end in a line to form a single path for electrons to flow:

The basic idea of a “parallel” connection, on the other hand, is that all components are connected across each other’s leads. In a purely parallel circuit, there are never more than two sets of electrically common points, no matter how many components are connected. There are many paths for electrons to flow, but only one voltage across all components:

Series and parallel resistor configurations have very different electrical properties. We’ll explore the properties of each configuration in the sections to come.

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Simple House Wiring

  • The basic electrical circuit

Electricity is the presence and flow of electric charge. Its best-known form is the flow of electrons through conductors such as copper wires. Electricity is a form of energy that comes in positive and negative forms, that occur naturally (as in lightning), or is produced (as in generator).  It has become an essential energy source in our daily lives. You are confronted with it everywhere. We use it during our work, at home and even for entertainment. If it is produced in a hydroelectric power station, it is very environment friendly too. The function of a hydro-electric power station is quite simple. The water of a river is directed into a channel. This channel leads to a turbine. The turbines driving-wheel is turned by the current of water. Because the turbine is connected to the generator, it gives the generator the turning movement and the generator is able to produce electrical energy.

 Basic knowledge

DC: – Direct current, electric current flowing in one direction. Eg. Battery. When the direct current flows, the lamp is able to light.

AC: – Alternate current that reverses its direction at regular intervals, the cycle being repeated continuously, the number of completed cycles per second being known as frequency. The symbol for frequency is hertz (Hz). It means one hertz stands for one cycle. We have 50 hertz per second which means 50 cycles for one second. Frequency = 50 Hz. The alternate current is produced by the generator. It does not matter if it is driven by a turbine or a diesel engine.

Active: – Where the electric current starts to move, never touch this wire. It will give you a shock. It is marked with plus (+).

Neutral: – Where the electric current flows. It is marked with minus (-).

Earthing: – Earthing prevents you from getting a shock. Always connect the green-yellow wire to the earth when you connect a light, switch, powerplug or powerpoint.

Volt: – Volt is the unit for voltage. Voltage is the amount of electrical power in an electrical circuit if it is not interrupted. The electrical power is always 250 Volt. The word comes from the Italian physician Allesandro Volta who realised the force of electric energy.

Ampere: – Ampere is the electrical force. It is named after a French physician Andrew Marie Ampere. You can compare it with a bucket of water, if one bucket of water is equal 250 V. If you switch on a light it is enough to pour one ¼ of the bucket into the electrical circuit per second. If you use the thickness planer you have to pour 5 buckets of 250 Volt every second into the electrical circuit. This is the electrical force. It is called ampere and the lamp needs ½ of one Ampere and the thickness planer needs 5 Ampere.

Ohm: – Ohm is the measurement of resistance, which occurs when electric energy is flowing. When we use the extension cord, you can feel that the extension cord gets warm. That happens because of the resistance. The same happens in a bulb. In a bulb there is a very thin wire. When electrical energy flows through this thin wire, it gets hot and gives off light. A lot off electrical energy would like to go through that thin wire, but because it is so thin, it provides high resistance and that resistance makes the wire hot

 Fuse box

A fusebox consists of different fuses. At the mainswitch the power comes in and is distributed to the other fuses. Usually the light is secured with one 8 Ampere fuse and the powerpoints with two 15 Ampere fuses. The purpose of the fuse is to break the electrical circuit if it is overloaded. If an electrical circuit is overloaded for a long time the wires will melt and the house could easily catch fire. Make sure that the electrical circuit has the correct fuse.

The fuse itself can consist of wire which will melt and break the circuit. Once the fusewire is broken, replace it with the same thickness.

The other type of fuse is the bemetal fuse, which is getting more popular. This fuse has two special metal strips in it and when they become hot, they bend and break the circuit. Afterwards, when they cool down, you can switch the fuse on again. They are much easier to handle than the wire fuses.

 Electricity accessories

a) Tools:

– Screwdriver

– De-sisalation pliers

– Combination pliers

b) Accessories:

– Bulb with Batten holder

– three core flex

– Connector

– Cable Clips

– Three pin plug

– Rocker switch

– Single powerpoint

– Fluorescent light

 

 How to connect switch, power point, light and power plug

a) Light and switch: – The active line and the earth wire go to the switch and from there to the light. The neutral wire goes direct to the light. Make sure that the active line wire is connected in the right way at the switch. Strip back the insulation just enough to allow the bare wires to be clamped tightly under the head of terminal screws without pieces sticking out.

b) Powerpoint: – Usually at the back of the powerpoint it explains where to connect the wires. Just follow the instructions and tighten the terminal screws.

c) Three pin plug:- Make sure you connect the earth at the right terminal. For the active line and neutral wires it does not matter which pins you use.

d) Main earth wire: – Usually the main earth wire is connected to a metal rod driven into the ground.

 Simple house wiring

You must start from the fusebox. The main active line wire is connected to the mainswitch in the fusebox. From there, the main active wire is distributed to three other fuses. One fuse is for the light and two fuses are for the power-points. A three core flex wire is distributed to the lights to make one electrical circuit and secured by one fuse. For the powerpoints you have to make two electrical circuits and secure them by two fuses. At the fusebox always connect the three core flex wire, earth to earth terminal, neutral to neutral terminal and active line to the fuse. The power-points usual mark where to connect the earth, neutral and active wire. At the light you have to be careful. Neutral and Earth are directly connected to the light, but Active has to go to the switch first and from there to the light. The earth from the switch is connected to the earth of the light.

Alternate switching

With the alternate switch you are able to switch on or off the same light from different switches. For that kind of switching you need a special switch called an alternate switch. The terminals of this kind of switch are marked with C,1,2 and loop. C at the first switch is connected to the active wire (usually red coloured). In that terminal the power comes in. Now you take an other three core flex wire and connect the red wire of the new three core flex wire to 2 and earth to earth. This core flex wire has to go to the other switch and repeat the connecting: red to 1, black to 2 and earth to earth (marked with loop). Then the terminal screw at the switch, which is marked with C is connected with one wire to the light. The neutral from the light has to go to the neutral of the fusebox.

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