Cable Surface Wiring (1944)

non-metallic sheath cable wiring shall comply with the provisions of article 300 and 336 of the national electrical code plan the work thoroughly consult your local inspector for local regulations remove only the number of knockouts required for wire entrances in this type box the knockouts can be punched out a wire holder is easy to use and the screw can be used to remount a smooth hole this junction box is to be used at the point of entrance the box is placed squarely over the hole already drilled for the entrance and all will help to locate and start the screws be sure the screws go in straight and are not forced so tight as to break the fitting so carefully examine all fittings make sure there are no missing screws or broken parts a knockout on this type fitting may be removed by breaking it off with pliers wherever practical locate fittings before running cable a convenience outlet may be mounted at any convenient height use the round head screws provided with the outlet be sure the screws are not too large for the countersunk holes in the fitting as a matter of convenience strip the cable at the bench always draw the knife away from the hand holding the cable use the rip cord to split the outer sheath when cable is to be used with porcelain fittings a little tape provides extra protection handle the cable carefully to prevent kinks wherever possible uncoil enough wire before starting the run straps placed within six inches of the outlet meets the code requirements form all corners carefully curve the cable around the corner too sharp return might break the cover or the insulation the code requires that straps must never be more than four and one half feet apart to make a neat installation keep the cable parallel to joists and studs in making bends the radius of the bend must be no less than five times the diameter of the cable in this case the cable is approximately one half inch in diameter therefore the radius of the bin must be at least two and one half inches in cutting cable place it well into the jaws and use full leverage be sure to leave an end long enough for connections it is better to have too much than too little cable must be strapped within six inches of any outlet skin the wire at the point of contact do not cut off the unskinned end of the wire just yet then use the back of the blade to clean the wire loop the wire clockwise around the screw twist off the end with a rotary motion the long wire end was left for just this purpose test the action of all switches before installing 42 inches from the floor is an accepted height for a switch this run will connect the switch and the junction box line up fittings and keep the cable run straight surface wire should be installed neatly if metal bar hangers are not available a wooden header may be placed between joists to support the outlet so this cable will run to the second junction box all cable connections and joints must be made in a junction or outlet box this cable will connect the junction box with one of the lamp outlets for greater protection cable may be strapped along the side of rafters and joists keep the cable parallel with the edge of the joist a few extra straps often improves the appearance again cable must be strapped within six inches of the outlet it is advisable to allow plenty of wire for future changes or additions pack the wires carefully twist them as little as possible this cable will connect the remaining lamp outlet after all cable is installed and the connections are made the wires are carefully formed in the junction box consult the code for number of conductors allowed in a box the box must be covered a service head is essential where this type of cable is brought into a building where only a short length of cable is required the assembly may be made at the bench the service head is attached to the building with wood screws final connections in the entrance junction box can now be made first connect the ground wire to one side of all lamps and convenience outlets second connect the hot wire to convenience outlets and switch third connect the other switch wire to the remaining lamp wire form the pigtailed wires in the box remember the code limits the number of wires in a box this circuit is protected by a fused safety switch in an adjoining building make sure the circuit is open before making final connections form drip loops to prevent moisture from entering the building test the circuit make sure that all independent outlets are alive now remember these points remove only knockouts required strap cable within six inches of all outlets cable must be strapped at least every four and one half feet radius of all bends must be at least five times the diameter of the cable it would look round round like the beach ball the ball is small enough so vicky can see its shape the earth is so very big she cannot see enough of it to tell that it is wrong father promises he will bring her a surprise that will help her understand this the next night father brings home the surprise it is a world globe the globe is a small model of the big world just as the play barn is a small model of a big barn there are many things to learn about our world it is made up of land and water father asks vicky if she can guess which color shows the part that is water the blue is the water father says that all the water is not in the ocean some of the water is in streams rivers and lakes the other colors on the globe show the part that is the land father and vicky find the tiny place on the world globe where they live vicky asks where cousin david lives she wonders what that part of the world looks like father tells her about the part of the world where david lives david's home is near a large lake around the lake are many trees [Music] in his part of the world there are big high mountains they are covered with snow in the winter even in summer some of the snow stays on the mountain peaks david and his father often go fishing on the lake [Music] david has many things to wonder about in his part of the world he asks his father where the water comes from that fills the lake father tells him the water comes from the snow on the high mountains [Music] when the snow melts it changes to water the water makes many streams like this one [Music] the small streams join together to make a big stream [Music] when the water runs over a cliff it makes a waterfall all the streams join together to make a river that fills the lake david says the lake is like a big bowl it catches all the water that comes down from the mountains david's part of the world is very different from the place where vicki lives vicki hopes someday she can visit david and go for a boat ride on the lake now vicky remembers her vacation on grandfather's farm she asks her father to help her find that place on the world globe on the farm there were flat lands and low hills grandfather told her flatland is good for farming [Music] vicky watched the workers cut and packed the lettuce or market [Music] [Music] vicky has learned many interesting things the round world is very big she can see only a small part of it at a time the world is made of many different kinds of land and water far away where david lives there are lakes and high mountains [Music] where grandfather lives the land is flat with low hills near vicki's home are cliffs rocks sand and ocean wherever you live there are many wonderful things to learn about our beautiful big world [Music] [Music] [Applause] a clean well-kept kitchen helps safeguard the purity of the food we eat but even in this kitchen there is an enemy to health the common housefly is capable of contaminating food and spreading disease this familiar insect can transmit serious diseases by feeding on man's food and infecting it with harmful microorganisms to prove this we can take any housefly and in the laboratory place it into a container of harmful bacteria culture we'll allow it to walk across the culture next we'll refrigerate the fly to slow down its movements now the fly numbed with cold can easily be transferred with sterile forceps to number one of these agar plates both number one and two plates are sterile after the infected fly is allowed to move across the sterile plate several times both plates are placed in an incubator and kept warm for 24 hours let's see the results first we'll look at the plate which the fly did not touch the number two plate it has remained sterile on the other plate number one on which the fly walked we can see scattered colonies of bacterial growth among the bacteria carried by house flies which might find their way into the human body are those microorganisms producing typhoid fever dysentery cholera and tuberculosis every year such disease-causing microorganisms infect people not only in our own country but in europe in the lands of asia and africa in fact in most places inhabited by human beings the common housefly can be found for it is one of the most widespread of insect pests understanding the life cycle of the house fly will suggest several methods of controlling this disease-carrying enemy in the united states as in other countries most houseflies begin their lives in moist decaying matter on farms where care is not constantly taken areas where animals are fed often make good breeding places for house flies female houseflies are attracted to waste food or slops among other farm areas where houseflies may breed are accumulated heaps of manure or masses of bran mash and silage in cities houseflies most often begin their lives in exposed decaying garbage to such places of moist waste swarms of female houseflies come to lay their eggs here's a female housefly laying her eggs the eggs flow out through a movable organ formed by the tip of the abdomen normally the female housefly lays five or six batches of anywhere from 75 to 150 eggs during her lifetime the eggs are left to incubate in the moist garbage or manure this incubation period takes from about 8 to 24 hours after incubation tiny white larvae called maggots emerge from the eggs for three to seven days the maggots feed voraciously on the waste material which surrounds them when the maggot is full grown it enters its next stage of development [Applause] this is a resting or pupil stage within three days to four weeks the pupil case splits open and the adult housefly emerges [Applause] in a few hours the moist wings and other exterior parts of the body harden let's examine the anatomy of the adult housefly on this large scale model we see that the housefly's body is divided into three sections and is supported by three pairs of legs characteristics of a true insect unlike many insects the house fly possesses only one pair of wings in place of a second pair there are organs called halterys or balancers short bristly hairs to which disease-producing microorganisms may cling completely cover the body and legs of the housefly [Applause] on the feet of the fly are pads which secrete a sticky liquid to which microorganisms may also adhere and which enables the fly to climb walls or walk on ceilings large compound eyes occupy most of the head area the mouth parts are of the lapping variety working somewhat like a mop these insects may feed upon a number of food materials unhelpful to man including manure garbage and even human sputum disease producing organisms often found in such materials collect on the body hairs of the house fly other microorganisms may be ingested or swallowed though the housefly cannot cause disease it can transmit or carry dangerous organisms often after feeding on filth the housefly manages to enter our homes the food we ourselves eat is an attraction for the insect pest [Applause] as it feeds the house fly regurgitate some of its previous food simultaneously the insect excretes waste materials sometimes this waste material is deposited on food by placing a specimen of this food under the microscope we see these droppings called fly specks as dark spots fly specs may contain masses of disease-producing microorganisms another habit of the house fly is cleaning its body and legs if the material removed consists of disease-producing microorganisms these two might be deposited on food these are some of the habits of the housefly that make it an enemy to man we can eliminate many of these pests through our knowledge of the house flies life cycle removing decomposing wastes in which the adult female housefly may lay her eggs will mean fewer houseflies in rural areas manure should be spread on the fields instead of allowing it to accumulate animal feed troughs should be regularly cleaned of waste foodstuffs barns and stables might be equipped with electric screens an effective means of killing adult flies in city areas concrete garbage containers are good protection against houseflies as are tightly closed metal containers during the summer when the housefly problem is greatest screen should be installed on all windows and doorways and fit tightly inside our homes food must be kept safely covered except when in use but sometimes no matter how careful we are flies manage to get inside our homes if it's just a case of a few flies a flyswatter will do the job and again for continued control of these insect pests there should be quick and thorough disposal of garbage [Applause] if the housefly problem becomes serious it's a good idea to spray rooms with insecticides remember however to put all food and eating utensils safely away and leave the sprayed room immediately after the job is done if the housefly problem in a community becomes very serious public health department inspectors will check possible trouble spots and make recommendations for controlling the breeding of housewives in any case let's remember that the housefly is an insect we must continually try to eliminate an understanding of the housefly its life cycle its anatomy and its potential danger better prepares us to control this common and harmful insect [Music] [Music] producer [Music] me [Music] la foreign principal foreign so foreign [Music] [Music] that [Music] foreign there [Music] oh [Music] statistically foreign foreign hello foreign [Music] is [Music] [Music] [Music] m foreign demons foreign foreign [Music] [Music] is [Applause] m foreign