ELECTRICAL SAFETY PRECAUTIONS

There  are  certain  safety  precautions  you should  observe  when  working  with  or  around electrical  appliances  and  equipment.  The following are some of the most common electrical safety precautions:

Personnel Safety

• Observe and follow all pertinent instructions and electric warning signs.
• Observe all safety precautions regarding portable electric lights and tools.  (Use rubber gloves and goggles.)
• Do not touch or operate any device that has a danger or caution tag attached without first contacting an authorized person.
• Do not go behind electrical switchboards.
• Do  not  touch  bare  electric  wires  or connections;  assume  all  circuits  to  be ALIVE.
• Do not remove steam tight globes from lighting fixtures.
• Don’t remove a plug from a power point by pulling on the cord; pull the plug instead.
• Switch off electrical items that are not in regular use at the plug and ensure that when we are away from the house for any length of time that you unplug and switch off electrical items as items left plugged in can be a fire risk and waste energy if left on standby.

• Do not use any electrical items in the bathroom unless specifically designed for use there, eg. Shavers and electric toothbrushes. Even with these items however, take care not to get wet and avoid plugging and unplugging with wet hands.

• Do not use items with damaged cords so that the wires are exposed. Either repair or replace. Check items regularly. 

• Do not use damaged sockets, replace with care when necessary. 

• Ensure any electrical items are approved standard when purchasing and keep them correctly maintained where necessary. Look for the BEAB seal of approval.

• Use the correct wattage light bulb for all light fittings.

• Circuit breakers and fuses should be the correct size current rating for their circuit

Top 10 Rules for Home Electric Safety

1. DON'T plug a bunch of stuff into one outlet or extension cord. It could damage the 

    electrical system in your house or even cause a fire.

2. DO ask grown-ups to put safety caps on all unused electrical outlets.

Covering outlets will also help save energy by stopping cold drafts.

3. DON'T yank an electrical cord from the wall.

Pulling on a cord can damage the appliance, the plug or the outlet.

4. DO make sure all electric cords are tucked away, neat and tidy.

Pets might chew on electrical cords, and people might trip and fall.

5. DO ask a grown-up for help when you need to use something that uses electricity.

6. DO look up and look out for power lines before you climb a tree.

   The electricity can go right through the tree branch - and right through you!

7. DON'T ever climb the fence around an electrical substation.

If a ball or pet gets inside the fence, ask a grown-up to call the electric company - they'll come and get it out for you.

8. DO remind your mom or dad to watch out for power lines when they're using a ladder, chainsaw or other outdoor equipment.

9. DO keep electrical stuff far away from water.

Most electrical accidents around the house happen when people use electricity near water.

10. DON'T fly a kite near power lines.

The kite and the string may conduct electricity - sending it right through you to the ground.

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COMMON ELECTRICAL TROUBLES IN THE CIRCUIT

GROUNDED – when a shock hazard is present causes by a leakage or excessive currents.

Ground Fault Interrupter

Ground fault interrupters are designed to protect from electrical shock by interrupting a household circuit when there is a difference in the currents in the "hot" and neutral wires. Such a difference indicates that an abnormal diversion of current from the "hot" wire is occurring. Such a current might be flowing in the ground wire, such as a leakage current from a motor or from capacitors. More importantly, that current diversion may be occurring because a person has come into contact with the "hot" wire and is being shocked. When a circuit is functioning normally, all the return current from an appliance flows through the neutral wire, so the presence of a difference between "hot" and neutral currents represents a malfunction which in some circumstances could produce a dangerous or even lethal shock hazard.

A Ground Fault Circuit Interrupter (GFCI) is an automatic electrical circuit breaking safety device for protection against line-to ground faults. A GFCI offers protection to users of electrical equipment against possible fatal electrical shock from faulty equipment or accidental grounding.

A GFCI constantly monitors current flowing in a circuit to sense any loss of current. If the current flowing through two circuit conductors differs by a very small amount, the GFCI instantly interrupts the current flow to prevent a lethal amount of electricity from reaching the consumer. The consumer may feet a painful shock but will not be electrocuted. Grounding may provide some protection for power equipment and double insulation of newer power tools presents lower risks of electrocution. However, GFCls are the most effective means for protecting consumers against electrical shock hazards.

SHORT CIRCUIT

A short circuit is a type of failure in an electrical circuit caused when the hot wire (black) touches another hot wire or touches a neutral wire (white). It can also be caused if there is a break in a wire or connection.

OPEN CIRCUIT

An open circuit is a broken path for an electrical current due to an open switch or frayed wire. Hence, no complete path for current flow. 

OVERLOAD 

An electrical load that exceeds the available electrical power and will cause heat.

LOOSE CONNECTIONS

When making a connection in a junction box, the length of wire in a box is important. The general rule of thumb is to install six inches of wire in a box in order to have enough to make proper connections.

Loose Wire Connections

Connections of wires should be made with wire nuts and twisted together. Loose connections on switches and outlets pose another problem. When tightening a wire around a terminal screw on a device, bend the stripped wire in a half-moon shape and put the open end towards the right. Tighten the screw in a clockwise motion until tight. This will draw the copper around the screw, thus closing the loop tighter. If you have the open end the other way, the half moon will actually open up a bit, causing the connection to not be as secure.

Loose Connections in Panels

Check the neutral and breaker connections in your panel to be sure they are tight. In this case, be sure to turn off the breakers before you begin. Safety first! A loose neutral will cause flickering lights and has been know to cause dim lighting in homes. Loose connections under breakers will cause the circuit to heat up and sometimes trip the breaker. This too can cause flickering of lights.

Proper Wires Connected to Terminals

Please take time and examine any connections that you make. Connecting a wire to the wrong terminal can cause electrical problems.

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ELECTRICAL TROUBLESHOOTING AND REPAIR

The 5 Steps of Troubleshooting Approach consists of the following:

Step 1 Observation
Step 2 Define Problem Area
Step 3 Identify Possible Causes
Step 4 Determine Most Probable Cause
Step 5 Test and Repair

Preparation

You need to gather information regarding the equipment and the problem. If there are equipment history records, you should review them to see if there are any recurring problems.  You must have on-hand any documentation describing the problem. (i.e., a work order, trouble report, or even your notes taken from a discussion with a customer).

Step 1 – Observe

Through careful observation and a little bit of reasoning, most faults can be identified as to the actual component with testing. Look for visual signs of mechanical damage such as indications of impact, chafed wires, and loose components. Sense of smell, listening to the sound of the equipment operating temperature would help.

Step 2 – Define Problem Area

Apply logic and reasoning to your observations to determine the problem parts of the equipment or circuitry that are operating properly and not contributing to the cause of the malfunction.

Step 3 – Identify Possible Causes

Once the problem area(s) have been defined, it is necessary to identify all the possible causes of the malfunction. List every fault which could cause the problem

Step 4 – Determine Most Probable Cause

Once the list of possible causes has been made, it is then necessary to prioritize each item as to the probability of it being the cause of the malfunction.

Step 5 – Test and Repair

Make sure you follow all your companies’ safety precautions, rules and procedures while troubleshooting. Test instruments can be used to help narrow the problem area and identify the problem component. Once you have determined the cause of the faulty operation of the circuit you can proceed to replace the defective component. Be sure the circuit is locked out and you follow all safety procedures before disconnecting the component or any wires After replacing the component, you must test operate all features of the circuit to be sure you have replaced the proper component and that there are no other faults in the circuit.

Follow up

• Did the component fail due to age? 

• Did the environment the equipment operates in cause excessive corrosion? 

• Are there wear points that caused the wiring to short out? 

• Did it fail due to improper use? 

• Is there a design flaw that causes the same component to fail repeatedly?

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TOOLS, MATERIALS AND EQUIPMENT USED IN THE INSTALLATION OF INTERCOM SYSTEM

Intercom system

An intercom system is an electronic communication device intended for limited private dialogue, directions, collaborations or announcement. Intercom can be portable or permanently mounted in buildings. Intercom can incorporate with telephones, walkie talkies and other mechanical such as signal lights and door latches.

A permanently installed intercom is generally composed of fixed microphone with speaker unit which is connected to central control panel by wires. A small home intercom might connect a few rooms in house. Larger system might connect all rooms in a school or hospital to central office. Intercom system in large building usually functions as public address system.

Intercom access control system are available with option of one call and one hand set to multiple call stations with hundreds of hand set. Intercom facilities can be available in audio only and audio video facilities. The audio and video system allows you to see who is calling at your front door, offices or gate before you allow or deny access. An intercom system can be connected to electric door, gates or electric locking devices.

Door & Camera Intercoms

Feel safe and secure answering your front door or gate without physically having to open them. The Hills intercom allows you to talk to the person and determine if they are known to you before you let them in. For added safety, you can disable front door answering from certain room stations e.g. children‘s bedrooms, preventing them from opening the door to strangers. A different door bell or chime sound may be used for different doors e.g. front, back, gate etc. to help you identify where the visitor is located.

Bedroom Intercoms

Ensure your peace of mind by being able to monitor your children when they are sleeping or playing. With the ‗automute‘ function, you won‘t be disturbed until the noise level from the monitored room station reaches a level that deserves your attention e.g. a crying baby. When your children are playing, the hands-free reply feature means you can communicate freely with them—they can answer you when you call without having to press any buttons. And with ‗sleep mode‘, you can program your room station to play music when you‘re ready for bed and automatically switch off after a certain time elapses.

Master Kitchen Intercoms

You can speak privately from any room station to other room station. By using the ‗selective room calling‘ feature, people in other rooms will not be disturbed. Using the Master Station, you are able to set the alarm clock, and choose which room stations will hear it. Make sure those who need to get up are up on time, and those who can sleep in are left alone. The Master Station has a digitally tuned AM / FM radio. Press one button to listen to your favorite radio station from any room within your home. Each room station retains individual control of volume.

Video / Lounge Intercoms

Not only you can hear your children when they are inside—the ‗monitor / camera‘ unit shows you what they are doing, whether they are inside or outside. Wherever your cameras are placed, the signal comes back to the monitor on this station for you to view. You can also switch between camera locations and monitor doors and gates, using them in conjunction with the front door answering units to see who is at your door.

Wiring Intercom

While every intercom product line is different, most analogue intercom systems have much in common. Voice signals of about a volt or two are carried atop a direct current power rail of 12, 30 or 48 volts which uses a pair of conductors. Signal light indications between stations can be accomplished through the use of additional conductors or can be carried on the main voice pair via tone frequencies sent above or below the speech frequency range. Multiple channels of simultaneous conversations can be carried over additional conductors within a cable multiple channels can easily be carried by packed switch digital intercom signals.

Portable intercoms are connected primarily using common shielded, twisted pair microphone cabling terminated with 3-pin XLR connectors. Building and vehicle intercoms are connected in a similar manner with shielded cabling often containing more than one twisted pair.

Two-wire intercom

Intercom systems are widely used in TV stations and outside broadcast vehicles such as those seen at sporting events or entertainment venues. There are essentially two different types of intercoms used in the television world: two-wire party line or four-wire matrix systems. In the beginning, TV stations would simply build their own communication systems using old phone equipment. However, today there are several manufacturers offering off-the-shelf systems. From the late 70's until the mid 90's the two-wire party line type systems were the most popular, primarily due to the technology that was available at the time. The two channel variety used a 32 Volt impedance generating central power supply to drive external stations or belt packs. This type of format allowed the two channels to operate in standard microphone cable, a feature highly desired by the broadcasters. These systems were very robust and simple to design, maintain and operate but had limited capacity and flexibility as they were usually hardwired. A typical user on the system could not choose who to talk to.

He would communicate with the same person or group of people until the system was manually reconfigured to allow communication with a different group of people. Two-wire routers or source assignment panels were then implemented to allow quick re-routing of a two-wire circuit. This reconfiguration was usually handled at a central location, but because voltage is used on the circuit to power the external user stations as well as communicate, there would usually be a pop when the channels were switched. So while one could change the system on-the-fly, it was usually not desirable to do so in the middle of a production, as the popping noise would distract to the rest of the production crew.

Four-wire intercom

Intercom systems are widely used in TV stations and outside broadcast vehicles such as those seen at sporting events or entertainment venues. There are essentially two different types of intercoms used in the television world: two-wire party line or four-wire matrix systems. In the beginning, TV stations would simply build their own communication systems using old phone equipment. However, today there are several manufacturers offering off-the-shelf systems. From the late 70's until the mid 90's the two-wire party line type systems were the most popular, primarily due to the technology that was available at the time. The two channel variety used a 32 Volt impedance generating central power supply to drive external stations or belt packs. This type of format allowed the two channels to operate in standard microphone cable, a feature highly desired by the broadcasters. These systems were very robust and simple to design, maintain and operate but had limited capacity and flexibility as they were usually hardwired. A typical user on the system could not choose who to talk to. He would communicate with the same person or group of people until the system was manually reconfigured to allow communication with a different group of people. Two-wire routers or source assignment panels were then implemented to allow quick re-routing of a two-wire circuit. This reconfiguration was usually handled at a central location, but because voltage is used on the circuit to power the external user stations as well as communicate, there would usually be a pop when the channels were switched. So while one could change the system on-the-fly, it was usually not desirable to do so in the middle of a production, as the popping noise would distract to the rest of the production crew.

All signal and alarm system has its specific function and uses which the purpose and need of its user. Deciding which of this device will be used can easily be done if you have basic knowledge of the feature and components of each devices in installing this kind of circuit.

Wireless intercom

For installations where it is not desirable or possible to run wires to support an intercom system, there are wireless intercom systems available. There are two major benefits of a wireless intercom system over the traditional wired intercom. The first is that installation is much easier since no wires have to be run between intercom units. The second is that you can easily move the units at any time. But with that ease of installation and convenience there is risk of interference from other wireless and electrical devices. Other wireless devices such as cordless telephones, wireless data networks, and remote audio speakers can interfere if they are near the intercom. Electrical devices such as motors, lighting fixtures and transformers can cause noise.

There may be concerns about privacy since conversations may be picked up on a scanner, baby monitor, cordless phone, or a similar device on the same frequency. Encrypted wireless intercoms can reduce or eliminate privacy risks and placement, installation, construction, grounding and shielding methods can reduce or eliminate the detrimental effects of external interference.

The United States and Canada have several frequency ranges for wireless intercom systems and other wireless products. They are 49MHz, FM band (200KH - 270KHz), 494-608 MHz, 900MHz, 2.4GHz, 5.8GHz, and MURS (150 MHz). There are also power line communication units that send signal over house wiring that have been referred to as wireless intercoms.

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INSTALLATION OF LIGHTING FIXTURE

Tools and materials you need

Tools:

• Wire cutters
• Electrical tester
• Ladder
• Screwdrivers (flat-head and Phillips)
• Adjustable wrench
• Pliers
• Pencil

Materials:

• Light Fixture
• Metal outlet box
• Wire nuts
• Electrical tape

Installing a ceiling fixture does not have to be a daunting task. Technically, lighting fixtures have only three wires--two live wires and one ground- to connect, so as long as the power is turned off, this can be a do-it-yourself project.

PROCEDURE IN INSTALLING LIGHTING FIXTURE

1. Cut the power to the existing light fixture in the ceiling at the house fuse or panel box.

2. Fasten the mounting plate to electrical box. The fixture you purchased will have its own mounting bracket and screws and wire nuts.

3. Clip the ends of the wires with a wire cutter. Use the wire stripper to remove the protective coating and expose fresh wire so the connection will be sound.

4. Attach fixture wires to the wires of the electrical box using supplied wire nuts. Match color for color.

5. Align the openings of fixture to the mounting plate and attach using the supplied screws.

6. Screw in the light bulbs and attached the globe. Make sure not to overtighten the cap or nut that holds the globe in place. Having it too tight can cause the globe to crack.

7. Turn on power to the room and flip the light switch to check the installation.

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TAPS, SPLICES AND JOINTS

Method of Skinning Electrical Wire

Removing the insulation in preparing the insulated conductors for making joints or splices, the insulation must first be removed from each conductor a proper distance depending upon the type of joint or splice to be made.
This process is called skinning or stripping.

Cleaning the Conductor

After removing the insulation, the wires must be thoroughly cleaned to ensure good electric contact between the ends of the wires so that the solder will adhere properly. The wire may be cleaned by scraping.

Types of taps, Splices and Joints of Conductor

Rat tail joints are used to join conductors in outlet boxes or when fixture leads are connected through conductors. The joints are made by skinning about 2 inches, the end of the conductor is to be joined. Then twist the bare conductors about six times.

Western Union Short tie splice - To make the splice, the wires are first skinned for about 3 inches at the ends. They are then placed in crossed position about 1 inch from the insulation. Four or five short turns are then wrapped on each side of the longest twist, and the free ends cut off and squeezed down closed to the straight position of the wire so that they will not extend over the surface of the short turns and permit the sharp to cut through the tape with the splice to be wrapped.

Western Union Long Tie Splice is used extensively for outside wiring and is quite similar to the short tie splice. It is also being used for interior wiring. The difference is that a number of long twist are made before wrapping the end turns. This is done so to withstand greater stress of pressure on the wire. The wire for this splice are bared about 4 ½ inches. They are then placed in the form of an X at a point midway between the insulation and the end of the base wire. Five or six long twists are then made and each side those turns are wrapped.

Britannia Splice is used in interior wiring where solid wires of No. 6 AWG gauge or larger sizes are to be joined and where large wire connectors or pliers are not at hand. The two wires are based for about 4 inches in a No. 6 wire. About ½ inch of the extreme end of each beat to almost a right angle to the straight portion of the conductor. A wrapping wire made of No. 18 bare wire copper is then cut to about 6 ft. in length and prepared by cleaning and bending in half. The large conductors are then laid together, one bent end pointing upward and the other downward. The center of the wrapping wire is then brought to the center of the conductor, one half of which is wrapped in one direction and other remaining half in the other as far as the best portion. The free ends are then forced through the grooves from one ends to the other end of the other of the large single conductors. The best ends are then cut off close to the joint.

Scarfed splice. It is used only on a large solid wire where there is an objection to the bulkiness of the Western Union or Britannia splice. The wires are bared for about 3 inches when a No. 6 wire is used.
The bared wire is then filed to a wedge shape starting about ½ inch from the insulations. A piece of No. 18 bare copper wire is cut to about 5 ft. in length and prepared by cleaning and bending in half.
The two file sides of the conductors are then laid together and wrapping wire wound around them as similarly done in Britannia Splice. The wrapping is completed by winding about six and seven turns of the free ends around the unfilled portion of the conductor.

Multiple wrapped cable splice is used more extensively on small strand wires and cables because these stands are more pliable and may be wound together without much difficulty. Large strands are rigid and require considerable time in making such a splice. To make the splice, the ends of the conductors are skinned at the distance of about 6 inches. The strands are cleaned and spread about apart. Next, the strands are cut about 3 inches from the insulation to right angle with the conductor. The strands of both conductors are then laced together, one group of strands wounds in the opposite direction. Care should be done that all strands in each group are wrapped simultaneously and parallel to one another.

Plain tap or Tee Joints is used to a great extent joining a tap or other conductor to a through conductor, as for example, a branch or main circuit. To make the joint, skin the tap wire about 2 inches and the main wire about 1 inch. Next, the wires are crossed intersecting about ¼ inch from the insulation of the tap wire and the main wire. A hook or sharp bend is then made in the tap and about five or six turns wound around the main wire. The joint is soldered and tape. Care must be taken that the solder flows and sticks through all the crevices and that the tape covers all part of the conductors, beginning and ending on the original insulation.

Knotted or loop, tap joint is very strong joint and will not untwist even enough strain is placed upon it. It is occasionally used in practice, particularly for temporary lighting systems, where time is not taken to solder joints. To make the join using No. 14 AWG wire, the tap wire is skinned about 3 inches and is then placed over the insulation of the tap and main wire. The tap wire is bent and hooked over the main wire and brought forward and bent over itself. Lastly, the remaining portion is wound into four or five short turns around the main wire.

Wrapped Tap, Tee Joint is used on large solid conductors where is difficult to wrap the heavy tap wire around the main wire. When a No. 6 AGW wire is used, both the main wire and the tap wire are skinned about 4 inches. The tap wire is bent into an L shape about ½ inches from the insulation so that it will rest along the side of the main wire. A wrapping wire is then prepared using size No. 18 bare conductors terminating beyond the bent of tap wire and up to the installation of the main conductor.

Ordinary Cable Tap or Tee Joint is used where large stranded wire or cables are tapped to a through conductor. To make the joint, the main strands should be scraped through with a knife blade or sandpaper. The tap wire of similar wire size cable should be skinned about 6 inches distance and the strands separated or fanned each strands of the tap into the shape. The main cable is placed into this V-shaped space and forced down to within 1 inch from the insulation of the tap conductor. One group of tap wires is then wound around the main conductor, each strands should be placed parallel to the other, and all wrapped at the same time and in one direction. The other group is wound in similar manner but in opposite directions.

Split Cable Tap or Tee Joint is used where stranded cables or wire are tapped to a through conductor. This joint is stronger than the ordinary cable tap and will not unwrap even though a strain is placed upon it prior soldering. To make this joint, the main wire is skinned a distance of 5 inches No. 14 American Wire Gauge (AWG) wire size is used and the strands thoroughly scraped as for the ordinary cable tap. The strands are next divided in half by forcing the screw driver through the center of the bared portion of the main wire. The tap wire is prepared by skinning it about 6 inches, scraping each strand until thoroughly cleaned and fanning out the strands so that they can be pushed around the space in the main wire. A space about 1 ½ inch should be left between the main wire and the insulation of the tap wire. In completing the joint, one group is wound around the main conductor, in one direction; and the second group is wound in the opposite direction.

The Through Fixture Joint is used where fixtures are connected to branch wires at an intermediate point. In making this joint, the end of one conductor is skinned about 2 inches and the other about 4 inches. At a point ¼ inches away from the insulation of the longer wire, three or four long twists are made similar to the rat-tail joint. The long bared portion of the long wire is bent over parallel with the free ends. Both free ends are then place alongside each other wrapped together around the straight bared portion.

Safety procedure in splicing and joining wire

Before the splice is made, the insulation is first removed on both ends with the use of an electrician’s knife or diagonal pliers. An electrician should be very careful in removing wire insulation in order that the wire will not be nicked by the knife or pliers to prevent breaking. However, a specially designed tool to avoid nicks is called automatic wire stripper. The function of the tool is to cut the wire insulation and remove it automatically by inserting the wire corresponding to the size of hole in the wire stripper. After removing the insulation, the end of the wire is twisted firmly. When the joint has been made, the correct practice is to solder it to prevent loose contact and to have a continuous flow of electricity. The splice and joint are then covered properly with an electrical tape in order to prevent short circuit.

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HISTORY OF ELECTRICITY

Electricity plays an important role in man’s conquest for existence .It has been said that it is here with us since the beginning of the time.

In 600 B.C, Thales a Greek philosopher accidentally discovered static electricity. Noticing that his garment had bits of hair and straw, Thales decided to remove them by rubbing piece of amber stone on his clothes. To his surprise, several pieces of straw clung to the amber when rubbed on the clothes, the amber became electrified and it attracted the pieces of straw. Thales simply wrote the incident and did not do anything about it because he could not explain the mystery. He did not know that he had just discovered static electricity.

In 1600, William Gilbert, an English Physician was able to put an electrical charged on the objects by means of friction or rubbing. He observed that two materials when rubbed together received opposite charges, that is, one object got a positive charge and the other a negative charge. He also noticed that two oppositely charged materials attract each other. Gilbert experiment was a re-discovery of static electricity, the word static means standing still or at rest. The Greek word for amber stone is “ ELEKTRON” and so the term electricity came about.

Great persons who involved in the discovery of electricity:

1760- Benjamin Franklin, An American scientist, proved that atmospheric electricity (lightning) and static electricity are the same.
1800- Alessandro Volta, An Italian Professor, discovered the voltaic file by means of stocking zinc plate (-) and silver plate (+).
1819- Hans Christian Oestered, A Danish Physicist proved in an experiment that current electricity can produced a magnetic field.
1831 Michael Faraday, An English scientist discovered the first electric generator.
1831- Samuel Morse, developed the telegraph.
1868-George de Clanche, developed the first practical dry cell.
1878-Charles Brush, invented the arc lamp
1879- Thomas Alba Edison, perfected the first electric bulb

Sources of electricity

1. Friction -It is a static electricity which is generated by rubbing two materials.
2. Chemical action - It is a great deal of the world’s electricity produced by batteries. These devices generate a different potential means of chemical action.
3. Heat action - Two dissolution metals bonded together in a junction when heated, exhibits a difference of potential. Such bond is called thermocouple. The trip of an iron wire, for example, may be welded to that of a copper wire. When, this junction is heated, the iron wire shows a positive charge and the copper wire has a negative charge. Electricity generated by heat action is called thermoelectric.
4. Light action - Photo cells are semi-conduction devices which convert light electrical energy directly into electrical energy. Either sunlight or artificial illumination may be employed. This action is due to the ability of lights energy to free electrons from the atoms of the semi-conductor material. This process is called photo-electricity.
5. Pressure - It is a difference of potential appears across the face of certain crystal such as quarts, when they are squeezed or stretched. This is called piezo-electricity.
6. Mechanical action - All electricity in large useful amount is at present produced by rotating machines working with the use of magnets. These machines, known as generator, are turned by water power, gas engines or steam engines and sometimes by electric motor.

There are many different types of mechanical power plants to produce electrical energy.

Hydropower is an energy obtained from flowing water. Energy in water can be harnessed and used in the foot motive energy or temperature differences. The most common application is the dam.
Power produced by the fall of water from a higher to a lower level and extracted by means of waterwheels or hydraulic turbines. Hydro-power is a natural resource available wherever a sufficient volume of steady water flow exists.

Nuclear Power is the method in which steam is produced by heating water through a process called nuclear fission. In a nuclear power plant, a reactor contains a core of nuclear fuel, primary enriched uranium. When atoms of uranium fuel are hit by neutrons they fission (split), releasing heat neutrons.
Nuclear power is an electrical power produced from energy released by controlled fission or fusion of atomic nuclei in a nuclear reaction. Mass is converted into energy and the amount of released energy greatly exceeds that from chemical processes such as combustion.

Solar Power is a power derived from the energy of the sun. A radiant energy produced in the Sun as a result of nuclear fusion reactions. It is transmitted to the earth through space by electromagnetic radiation in quanta of energy called photons which interact with the earth’s atmosphere and surface.

Wind Power is the kinetic energy of wind or the extraction of this energy by wind turbines. Windmill machine converts wind into useful energy. This energy is derived from the force of wind acting on oblique blades or sails that radiate from a shaft. The turning shaft may be connected to machinery used to perform such work as milling grain, pumping water, or generating electricity. When the shaft is connected to a load, such as a pump, the device is typically called a windmill. When it is used to generate electricity, it is known as a wind turbine generator.

Fossil Fuel Power Plant (FFPP) – (also known as steam electric power plant in the US, thermal power plant in Asia, or power station in UK). The most common source of energy is fossil fuel. Fossil fuels include coal, oil, and natural gas. Fossil fuel is formed from the remains of plant and animals which live thousands of years ago. The burning of those fossil fuel provides energy which can be used to generate electricity.

Geothermal power comes from heat energy buried beneath the surface of the earth. In some areas of the country, enough heat rises close to the surface of the earth to heat underground water into steam which can be tapped for use in steamturbine plants. Geothermal Power is the energy extracted from the heat generated by natural concentrations of hot water and steam in the earth’s interior. It can be used in electric power generation and direct heat applications such as space heating and industrial drying processes.

Tides is another kind of energy that involves water. Ocean tides can be used to turn turbines to generate electricity. For this to be possible, a dam must be built across the month of a bay. Water then in trapped behind the dam at the high tide. At the low tide, the water is allowed to run out through the dam and used to turn on electrical generator.

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