Credit Points 2
LET'S BE FRIENDS WITH ELECTRICITY Plan a Hazard Hunt
Electricity can be your important lifelong friend and helper, so you will want to know all you can about it and how to treat it properly. However, careless and improper use of electricity can do a lot of harm. Used properly, and treated with respect, electricity can do wonderful things to help you every day in many ways.
For safe and proper use of electricity, all wiring, fittings, insulation, cords and plugs must be in good condition. You can be a detective and track down defects in any such type of electrical equipment that you may be using in your home or on your farm.
When you find anything that is wrong, and know where it is, and know what to do about it, you can very likely correct the condition yourself, such as replacing a worn extension cord with a new one. If you find defects in permanent wiring, or some places where wires are bare or terminals are needed, you should tell your parents about them.
SAFETY FIRST, remember, should always be on your mind when working with anything electrical.
1. Have A Hazard Hunt
Go on a Hazard Hunt to see how many electrical hazards you can find. Look for defects such as broken insulation, worn cords, splices that are not properly soldered and taped, loose connections, or switches that aren't working properly.
There are many ways to have a Hazard Hunt. Choose the method that will be the most fun. Use the Hazard Hunt Guide in this outline to check your home, and other buildings. Maybe you'll want to have a friend help check your home, then you help him check his. Or, why not give each member of your family a Hazard Hunt Guide and have a contest? Parents may want to team up against you and other younger members of your family to see which team can find the most electrical hazards in some set time—say 30 minutes.
Have a Hazard Hunt Committee in your club check all member's homes and buildings and report its findings at the next club meeting.
To Make It More Fun
1. Put a hazard tag, like the one shown, (Figure 1) by each hazard that is found. Leave it until the hazard is corrected. Have another contest to see which member of the family corrects the most hazards.
Figure 1
2. Report on your Hazard Hunt at the next club meeting. Tell about the Hazards found, and what you have done or plan to do about them.
3. Suggest that the entire club have an Electric Hazard Hunt at your club meeting places or any community building. This could be part of one meeting.
4. Have a contest between two teams in the club to see which team can get the most homes in your community checked by the Hazard Hunt Guide. Losers could give a party for the winners.
2. Get Others Interested
Promote a community Electric Hazard Hunt. Enlist the support of power suppliers, electric supply and equipment dealers, schools, newspapers, radio and television stations.
What To Look For
Make a complete tour of your home and other buildings and see how many hazards you can locate. When you find a hazard, put a tag near it to mark it.
SAFETY TIPSPut hazard tagsnearthe hazard butnotdirectly on broken or frayed wires, insulators, fittings, or other wiring equipment. Do not touch them either. Badly-frayed wires should be disconnected immediately from the power supply. In this way, you will not expose yourself to shock by accidentally touching an exposed live wire that may be carrying current.
Put hazard tagsnearthe hazard butnotdirectly on broken or frayed wires, insulators, fittings, or other wiring equipment. Do not touch them either. Badly-frayed wires should be disconnected immediately from the power supply. In this way, you will not expose yourself to shock by accidentally touching an exposed live wire that may be carrying current.
Wiring and Protective Devices
1. Cable or conduit splices not in boxes——
2. Cable or conduit not securely clamped in boxes——
3. Conduit or armored cable not properly grounded——
4. Cracked or broken insulators (Figure 2)——
5. Wire not completely covered with insulation——
6. Worn insulation on wire——
Figure 2
7. Old unused wiring not yet removed——
8. Outlets, junction and switch boxes not securely fastened and covers not in place——
9. Switches not working properly (sparks fly as switch is flipped) (Figure 3)——
10. Fuses not of proper ampere rating for circuit——
11. Extension cord used in place of permanent wiring——
12. Pull chain socket without an insulating link in the chain——
13. Pull chain socket near plumbing fixtures or where hands may be wet or one may stand in water——
Figure 3
14. No moisture-proof cords for outside weather conditions or heavy rubber cords for motors and motor driven appliances
Lighting
1. Fixtures in farm buildings installed so that they might be easily damaged
2. Lights in haymows and other dusty locations not protected by dustproof globes
3. Outside sockets not waterproof
4. Heat lamps not properly supported by non-current carrying wire, chains, or brackets (Figure 4)
5. Light bulbs not frosted, shaded, or placed so that light is diffused to prevent glare
Figure 4
Auxiliary Wiring
1. Outlets overloaded—in other words, "octopus wiring"
2. Extension cords placed under rugs
3. Extension cords run through doorways (Figure 5)
Figure 5
4. Extension cords or lamp cords should use underwriters' knot (Figure 6)
Figure 6
5. Plug connections fuzzy (Figure 7)
Figure 7
6. Extension cords run over heaters or radiators
7. Extension cords, or appliance or lamp cords, worn or frayed
8. Heating appliances without regular asbestos covered wire
9. Open sockets or outlets where a baby or small child might stick a finger or metal toy
10. Broken plugs (Figure 8)——
11. Loose prongs on appliance or lamps plugs——
Figure 8
Make a chart listing the hazards, their locations and what you did about them. Make your own chart and list what you find.
Show and tell others how to have a Hazard Hunt.
Check with your leader, then ask your power supplier or a local electrician to tell you about safe electrical wiring, connections and fixtures.
HazardLocationWhat I DidLoose prong on lamp plugLiving RoomReplaced with new plugCracked insultor on service wire in houseBack of houseNotified power supplierConduit not securely clamped to boxBasement by fuse boxNotified parentsExtension cord, old and wornBasement, by washing machineReplaced with new rubber-covered one and protected it from water
Credit Points 3
When was the last time you wanted to get a simple message like "You're wanted on the telephone," "There's someone here to see you, "or "There's a car in the driveway," to someone around your place? Did you have to walk or run some distance and perhaps shout, too, to be heard by the other person? Perhaps you had to stop some other work, or interrupt your favorite kind of fun, to do this bit of messenger work.
If the nature of the message is like one of those mentioned, and the number of people in hearing is not too great, then perhaps you can use bells or buzzers or both to do some of your messenger work for you. Even though a bell or a buzzer can't talk, it can convey a message.
1. Learn how bells and buzzers work, and learn about the many different kinds.
2. Plan and install a bell system for your home or farm.
Electric bells and buzzers use the same basic principle as the telegraph system, invented by Samuel Morse in 1840. Although not as important today as it was before radio, telephone, and teletype became common, the telegraph is still in use.
Bells and buzzers, however, are very common and have many uses. They are most often seen in the form of doorbells, and rare is the new home that does not have one or more. Service stations have bell systems to let the operator know that a car is waiting at the gas pumps. A clock signal reminds the homemaker when the cooking time is completed. Children are called to and released from school classes by means of bells and buzzers.
Also, various alarms employing bells and buzzers warn us when it's time to get up, or even that the place is on fire, or that a burglar is trying to break in!
Let's find out how bells and buzzers work, what different kinds there are, the different ways you can control them, and how you can put them to work for you.
You'll find that buzzers and bells can help you with your 4-H projects, and with the proper controls, can be your eyes and voice in a dozen places at once.
If we were to look at an electric bell with the cover off, we'd find that it would be very much like Figure 1.
A push on the button, which is just a switch that is normally held "open" or off by means of a spring, sends the current from the battery or transformer through the circuit.
Figure 1
You will see that the current passes first through two small coils of wire, and each coil has at its center a piece of soft iron called the core. When the current is on, the core becomes magnetized and attracts another piece of iron called the armature with its clapper attached.
This action rings the bell, but it also breaks the current by pulling the spring away from the screw on its return to the power supply.
With the power off, the electromagnet lets the spring return the armature to its normal position, contact is made again, and the cycle starts all over again—just as long as you continue to push on the button.
Buzzers work exactly the same way, except that they do not have a bell and depend instead on the vibration of the armature for a noise that's not as loud or as musical.
Gongs or chimes, that strike only once when the button is pushed, are made by connecting the armature with the screw by means of a flexible wire.
Most buzzers and bells work on a much lower voltage than you normally find in the wires in your house. Some are made to work at 6 volts, others at 10 volts, and still others at slightly higher voltages.
You can get these low voltages by using one or more batteries, or by using a transformer connected to your house current. Most bells and buzzers are now powered through transformers.
The push button is the most common means of control. You can use one button to control several bells, or several buttons to control one bell, or have several buttons control several bells. Because low voltage is used, adding extra buttons is simple, inexpensive, and safe.
Buzzers and bells can also be controlled by:clocks, as in the interval timer on an electric range or in a school class bell system;temperature detectors, as in a fire alarm or freezer alarm;door and window trips, as in a one-man repair shop or in a burglar alarm; andtreadles, as in the driveway of a service station.
Figure 2
Some of the many different types of bells, and various ways of controlling them are suggested in the table below. Just remember that no matter what the job or conditions, you can probably find a bell or buzzer and controls that suit your need.
SOME TYPICAL JOBS FOR BELLS & BUZZERSJobType of bell or buzzerNumber and location of bells and buzzersType of controlNumber and location of controlsSummon others to the telephoneIn the house— small to medium buzzersIn outbuildings— medium to large bellsOutdoors— large weatherproof bellAll transformer-poweredEnough to cover all usual work locationsPush-buttonsOne at the telephone and each extension phoneNotify club member that car is at his produce standMedium to large bell— transformer-poweredOne may be enough—if mounted on the back of the standHose diaphragm(Complete driveway units including control, are available, ready to plug in.)One—in the drivewayWarn of power failure to incubator or brooderBattery-powered buzzer, medium sizeOne near the poultryman's bedroomRelay, held open as long as power is on, closed by spring if interruption occursOne, at main switch of hatchery or brooder houseWarn of dangerously warm temperature in freezerBattery-powered buzzer, medium sizeOne, in or near the kitchenTemperature detector (sensitive thermostat)One, with bulb inside freezer
To save your time and steps when the telephone rings for someone else in your family who is some distance away, you can install a simple bell or buzzer system to summon that person.
First, you must plan what you are going to do. On a large sheet of paper, draw to scale (roughly) a plan of your house and grounds, including those places where phones are located. It will help if you rule off your paper in 1/8" or 1/4" squares and let each square equal one foot. Show the location of poles supporting your wiring.
Next, pick out those areas where you or others would likely be when someone else would answer the phone and want to call you to it.
After you have thought about this, and talked it over with members of your family, show locations on your plan where you think you would like to have buzzers or bells, and show a button beside each telephone. (Generally, you should have a bell or buzzer near each phone, also.)
Figure 3 shows diagrams of various types of systems, and will help you determine the number of wires you will have to install to connect the buttons and bells that you have planned.
Inside, you will connect your transformer and the various buttons and bells with ordinary indoor bell wire. Outdoors, however, you should use weatherproof 2-wire or 3-wire telephone twist.
Show on your plan the distances that must be traversed by each type of wire, and show the number of conductors in each. Don't overlook the vertical distances (one floor to another).
Figure 3
Because no two situations are just alike, it will be necessary for you to make your own list of materials.
As a guide, however, here is a list of typical materials, with the quantities left blank, for you to fill in as your own requirements and measurements dictate.
10-volt transformer_____ Door buzzers_____ Doorbells_____ Weatherproof outdoor type bells_____ ft. indoor bell wire_____ ft. 2-wire weatherproof telephone twist_____ ft. 3-wire weatherproof telephone twist_____ lbs. staples (insulated)_____ entrance insulators (for attaching weatherproof to buildings and poles)
Because your transformer must be wired into your regular house current, you should have some help on this from an electrician or other qualified person. Also, you should get that person to review your plans and materials list before you place an order.
With the aid of an electrician or other qualified person, install your transformer, and test it.
You may then go ahead and complete your signal system, checking carefully with your plan, and making sure that your installations are both electrically and mechanically secure.
Test your system in all possible ways that it might be used.
Build a demonstration board incorporating a farm or home layout, with pushbuttons or other controls and bells and buzzers appropriately located. Show and tell how the system would save time and energy.
Show and tell how some of these work, and their value: power-off alarm, freezer alarm, fire alarm, driveway alarm.
Ask your power supplier or your nearest electrical supply house for catalogs or literature on various types of signal systems, or ask a dealer to show you equipment he has in stock.
Credit Points 2
What would you do if you saw someone who had been hurt by electricity?
Did you know that you could save his life, if you had taken the time to learn and practice a few simple rules of electrical first aid?
First aid training equips you to know what to do and what not to do for the injured until medical help can be obtained. While the main benefits are for you and your family, no one can call himself a good citizen if he fails to help a stranger who has been hurt.
The information given here is only for electrical injuries. Perhaps what you learn will inspire you to take a complete course in first aid.
Learn how to prevent electrical accidents, and what to do if an electrical accident occurs.
1. Make an electrical hazard hunt in your home or on your farm. Point out to your parents everything that should be repaired or replaced for safety's sake.
2. Read the first aid suggestions that follow. Learn them.
3. Get to know the six steps that are outlined for mouth-to-mouth rescue breathing. Practice them on your brother, sister, or parents. Teach the entire family how to do it.
In this day of hundreds of uses of electricity, you should know about electrical dangers. Electrocution can occur from either low voltage (household type) or high voltage currents. Sometimes household voltages are more hazardous because people underestimate the dangers involved.
A fraction of an ampere passing through your heart muscles can be fatal. Your body offers some resistance to the flow of electricity to ground. If you are standing on wet ground or in water, or if your skin is damp, this resistance is greatly reduced.
Wire cables within walls and cords on appliances are all insulated with a shock proof covering. Continued use, age, or damage may expose a bare wire and create a hazard. The point of exposure need be only a fraction of an inch. Cords are often used and abused. Exposed wires and signs of wear are danger signals.
Always be wary of overhead wires. People have been injured or killed when kite strings, model plane control lines, irrigation pipe, and water well equipment have come in contact with the power supplier's or their own overhead wiring.
Underwriters' Laboratories (UL) have taken steps to see that minimum safety standards are met in the manufacture of electrical equipment. Look for the UL label when you buy cords or appliances. Never place cords under carpets or furniture, or drape them over a nail. Replace or repair worn cords without delay.
Be especially careful when operating electric devices in the bathroom. Keep in mind the dangers of a wet floor, grounded metal pipes, and wet skin. Turning on an AC radio while you are taking a bath is asking for real trouble.
There may be shorts in electric devices. Keep your hands dry when using them, and do not touch them along with grounded metal objects. If you ever get a slight shock, sound the danger signal and do something about it.
Your first thought in rescuing a victim from an electrical accident should be your own safety. Speed is also important, because a few seconds or minutes may save a life.
The first question you should ask yourself is "Can I quickly turn off the power?" This would be easier to do in the home than outside. In the case of a victim trapped in a bathtub from a radio accidentally knocked into the water, it might mean simply removing the plug from the wall outlet. If a victim is found grasping shorted, permanently installed equipment and cannot let go, the main switch might be used for quick release of the current.
Outdoors, especially with high tension wires, your danger in rescue is much greater. To handle the victim, touch him only with a long dry stick, dry rope, or a long length of dry cloth. Be sure your hands are dry and that you are standing on a dry board. A broom might be a good lever to pry a victim from a high tension wire but never use a green stick containing sap.
Once the rescue has been made and the victim is free of further danger, check to see if breathing has stopped. If so, start artificial respirationimmediatelyand send someone for a doctor.
Artificial respiration must be started as soon as possible after normal breathing ceases.Most persons will die within 6 minutes or less if breathing stops completely unless they are given artificial respiration.Precious minutes may have passed before you get to the victim. Since the victim may be within seconds of death by the time you are able to touch his body, you should seek to obtain an air flow to and from the lungsimmediately.
The victim may seem stiff as an effect of the current, so don't give up easily. Continue the procedure for several hours. If transportation is necessary, remember that there may be internal injury, fractures, or severe burns.
There are various effective ways to give artificial respiration, each with its advantages and disadvantages. The mouth-to-mouth method is recommended as a good one to master. It can be used on victims of drowning, suffocation, and asphyxiation, too. People have been known to save lives with less exposure to the correct procedure than you are getting by reading this. So, pay attention and remember what you read.
Step 1. Turn the victim on his back. Wipe out victim's mouth quickly. Turn his head to the side. Use your fingers to get rid of mucus, food, sand, and other matter.
Head Position
Step 2. Straighten victim's head and tilt back so that chin points up. Push or pull his jaw up into jutting out position to keep his tongue from blocking air passage. This position is essential for keeping the air passage open throughout the procedure.
Push Jaw Up
Pinch Nostrils
Step 3. Take a deep breath, place your mouth tightly over victim's mouth, and pinch nostrils closed to prevent air leakage. For a baby, cover both nose and mouth tightly with your mouth. (Breathing through handkerchief or cloth placed over victim's mouth or nose will not greatly affect the exchange of air.)
Breathe
Step 4. Breathe into victim's mouth or nose until you see his chest rise. (Air may be blown through victim's teeth, even though they may be clenched.)
Step 5. Remove your mouth and listen for the sound of returning air. If there is no air exchange, recheck jaw and head position. If you still do not get air exchange, turn victim on side and slap him on back between shoulder blades to dislodge matter that may be in throat. Again, wipe his mouth to remove foreign matter.
Step 6. Repeat breathing, removing mouth each time to allow air to escape. For an adult, breathe about 12 times per minute. For a child, take relatively shallow breaths, about 20 per minute. Continue until victim breathes for himself.
1. A broken arm should be splinted before artificial respiration is applied to a victim who is not breathing.
2. A person who has been severely shocked with an electric current should lie down.
3. A doctor should be called even though you successfully have revived a victim's breathing.
4. A fraction of an ampere through the human heart muscles can be fatal.
5. A copper wire would provide a better path than your body for stray currents, therefore all appliances should be grounded if possible.
6. Outside wires are never a hazard because they are covered with insulation when they are installed.
7. Cords need not be repaired until you can see bare wires.
8. Tuning in an AC radio while you are bathing is always dangerous, even though your hands are dry.
9. In an emergency, a broom is an acceptable tool for prying a victim off a high tension wire.
10. In mouth-to-mouth breathing, an adult's lungs should be filled 12 times per minute and a child's 20.
Show how to deal with an electrical first aid "problem" given to you by your leader.
Ask your leader to have a first aid expert put on a demonstration. (Many industrial plants and power suppliers have such people.)
Credit Points 3
In ancient times, people thought that heat was a material just as air is. They called it "caloric". When something got warm, they said, caloric flowed into it. When something cooled off, caloric flowed out of it. It did not bother them that they could not see caloric. They could not see air either!
Now we know that heat is not a material. It does not take up space. It does not weigh anything. Instead, it is a form of energy. And when we say that heat is a form of energy, we mean that it can be used to do work.
1. Make a simple resistance heater.
2. Make some popcorn by:
(a) conduction (b) convection (c) radiation
There are at least four ways that electricity can make heat. The one that we'll cover here isresistanceheating. (The others are:dielectricheating, where the lines of force of an electrostatic field pass through a non-conductive material and heat it; theheat pump, which is a refrigerator in reverse; andelectronicheating, which uses high frequency waves similar to radio waves to create high speed movement of the molecules or tiny particles which rub together to make heat.)
Resistanceheating occurs because every conductor of electricity opposes the flow of current through it. Some conductors resist more than others. When they do, a certain amount of warming takes place. The more resistance that is offered, the more heating there is.
Some materials, like silver, copper, and aluminum, offer little resistance. We say they are good conductors.
Other materials, like iron, offer more resistance. They are still conductors, but not as good as the others mentioned.
Thesizeof the conductor, and itslengthare the other two things that affect its resistance. Thesmallerit is, the greater its resistance. Also, thelongerit is, the greater its resistance. Therefore, when we only want tomoveelectricity from place to place, we want relatively large, "good" conductors. Here, we do not want to make heat. In fact, we want to avoid it, because too much heat in the wrong place can cause a fire.
But when we want heat, we choose relatively small, "poor" conductors, and the more heat we want, the longer they must be. If you will think of the filament inside a lamp bulb; you may recall that it is a very fine wire, coiled so as to get a maximum length, and made of tungsten which has a high resistance.
Because of all these factors, this filament glows at a white heat, and is a source of both light and heat.
Materials you will need:1 dry cell battery1 foot iron picture wirePliers
Use a short strand of iron picture wire and hook the ends to the terminals of a dry cell battery. Use pliers so that you do not burn your fingers. Disconnect the wires as soon as they become hot. Tell why the wires heat.
Conduction occurs when you set a pan containing food right on a heating element. An egg cooking in a hot frying pan is a good example of conduction at work. This method is the most efficient single way of using electric heat for cooking.
Convection warms food in pans that are not actually touching the heating element. It uses the hot air around the element to carry heat to the pan.
Your oven in your range works by convection. Most houses are warmed in winter in the same way. The heat produced in a furnace warms the air as it circulates through. This air in turn keeps your body warm.
Radiation heating is more difficult to explain. It results when heat or energy waves strike an object and are converted into heat. The energy we receive from the sun is a good example. When you are wearing dark clothes on a chilly day, you may become uncomfortably hot. The sunshine warms you even though the air around you has not been heated. Radiant energy has a way of being absorbed by dark objects and reflected by light colored or shiny surfaces. Did you ever notice how snow melts faster on a black top road than it does on a concrete road?
The electric heat lamp is one of the most familiar sources of radiant heat. Other examples are panels and cables that are built into the walls and ceilings of homes to provide heat.
How do you make popcorn? Did you know that you can do this kind of a heating job three different ways?
Materials NeededPopcornCooking oil or shorteningSalt and butter4-qt. saucepan, with cover. (A glass cover is preferred.)PotholderElectric range2 250-watt heatlamps2 spring clamp type lampholdersWire mesh corn popping basket or wire mesh kitchen strainer (improvise a screen wire cover)
First, make popcorn the way you usually do. Set a front surface unit control on the range at "medium high". Pour enough oil to very lightly cover the bottom of the pan. When the pan is hot, pour in enough popcorn to cover the bottom with one layer of kernels. Use the potholder in one hand to hold the cover on, and with the other move the pan back and forth across the unit. When the popping stops, remove from the heat.
How did the heat get to the popcorn?
Second, make popcorn in the oven. Add the oil to the pan, cover it and put it in the oven. Turn the oven on, with the automatic control set at 400°. When the oven indicator light goes off, this means that the proper temperature has been reached. With the potholder, remove the pan and add one layer of popcorn kernels. Replace the pan in the oven. When the popping stops (listen for it) remove the pan.
What kind of heating took place here?
Third, make popcorn with the heat lamps. Clamp the lampholders to the back of a chair or other vertical support. They should be 6 to 8 inches apart and pointed directly at each other. Put about 2 tablespoonfuls of popcorn in the Wire basket or strainer. Do not add oil. Hold the basket midway between the two lamps. When the popping stops, turn off the lamps.
What kind of heating was this?
Now, butter and salt the popcorn you have made and share it with others.
1. How is heat transferred from one body to another?
2. Could chicks or pigs receive warmth from a heat lamp without the air in the pens becoming warm? Explain.
3. How does a broiler unit in a range cook meat?
4. How does an oven bake food?
5. Tell why iron picture wire was used instead of copper wire for your heating demonstration.
Credit Points 2
In ancient times, people found certain rocks that clung together in bunches. These rocks were very mysterious. People didn't understand them and many superstitions grew up about lodestones, as these rocks were called. Lodestone (sometimes spelled loadstone) means leading stone. People even told Columbus not to sail out of sight of land because a giant lodestone was just over the horizon waiting to pull all the nails out of his ships.
The Chinese were the first to use magnets. They found that if you hung a lodestone by a string, one end of the stone would always point in the direction of the North Star. They had the first magnetic compasses.
An artificial magnet can be made by stroking or gently rubbing a piece of steel with a lodestone. This piece of steel then can be used to magnetize another piece of steel. This can be continued on and on. Lodestones are not always available but you can get the same results with an electric current. So, magnetism and electricity are very closely related.
Learn about magnetism by doing the experiments that follow.
Seeing is believing!
Materials You Will Need2 dry cell batteries (#905)A few feet of No. 18 bell wire3 steel knitting needles or similar hard steel2 ft. of light threadSheet of light cardboard or stiff paperPermanent magnet (bar or horseshoe)Compass1 or more large nails or spikesRed and black china-marking pencils or crayonsIron filingsWire cuttersCarpet tacks
(Iron filings usually can be found under the grinding wheel in a shop. If you can't find any, rub some steel wool pads together to produce bits of metal that will do.)
Cover the permanent magnet with the cardboard or paper. Sprinkle iron filings on the paper. Tap the paper and note the pattern formed. Strings or lines of filings pass from one pole of the magnet to the other. The area covered by the filings is the center of the magnetic field. To remember this, you might compare the magnetic lines of force that arrange the iron filings to the contour strips in a farmer's field.
This magnetic field is one of the important things in our everyday life with electricity. If it were not for the magnetic field, we would not have electric motors. Telephones, radios, television, and many other things we use every day also depend on this magnetic field.