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Play It Safe

Caution, common sense and proper grounding technique will prevent   needless   accidents

Opening the main switch kills current in all of the house wiring; however, this also means it will affect the refrigerator, furnace, etc. In many cases opening only a branch circuit is sufficient A posted warning sign on an open circuit is helpful.
 
The following item appeared recently in a New York newspaper. (Only the names of people  and places have  been changed.

Business Man Killed Wiring Fan In Attic

Townville, L. I.—John J. Doakes, 44-year-old business executive, was killed by electricity today while installing an exhaust fan in the attic of his new $40,000 home at 999 Shore Drive.

Members of the Townville Fire Department had to tear out part of the ceiling in an attic room to remove the body, which was crumpled in the space between the ceiling and the roof. An electric wire, which he was connecting to the fan, was clutched in one hand.

The accident occurred about 2 P.M. while his wife and their three children, two boys 19 and 15 and a girl 12, were on a shopping trip. His body was found about 3 P.M. by a neighbor, Joe Jones, who had been called by Mrs. Doakes after she was unable to find her husband when she returned.

Mr. Doakes was sales manager for a printing firm. He had moved into the house just a week ago.

This tragic accident was obviously the result of simple, unadulterated carelessness. The victim had forgotten or neglected to kill the branch circuit on which he was working, and he himself was killed instead.

There is a difference between "forgetting" and "neglecting" in cases of this kind. A man can be fully aware of the joltage behind power line voltage, and he can fully understand the importance of removing fuses or snapping circuit breakers open. However, while he may intend to open the circuit, he may simply forget to do so before he climbs into the attic with his hands full of tools.

There is the strong possibility that the victim of the fan accident left the power on deliberately, so that he could have light while working in the cramped attic space. He may have figured that there was no danger as long as he handled only one live wire at a time. This was sheer neglect. Maybe he did handle a single wire at a time, but maybe, when he held the "hot" line, he brushed against the grounded sheath of BX as he groped on the floor for a roll of tape.

Clearly, the moral to all this is: PLAY IT SAFE. It's easy to do so by following a    few,    common    sense    simple    rules.

DON'T! Some housewives put mixers and blenders in the sink, while they are connected and running, to catch possible spillover. This is a dangerous practice, because the sink and the pipes near it are well grounded electrically, and there is always the possibility of a live circuit forming between them, the body, and one wire  of connected appliance.
 
It would appear at first sight that the easiest way to avoid shock, when making repairs or installing new equipment, is merely to yank open the main switch. This deactivates all the wiring in the house and therefore you can touch anything with complete safety. This move is practicable if the work will take only a few minutes; say up to about 15 or 20. You must remember that pulling the main switch removes power from the kitchen refrigerator (and food freezer), which might be undesirable in warm weather; and also shuts down any modern heating plant, which might be undesirable in cold weather. With the main switch off you have no electric light, so you can work only in daylight in an area near a window.

Although an open main switch gives 200% safety, you can still have 100% safety, and the convenience of power for light, tools, etc., by removing the branch fuse only for the circuit that you want to touch. Presumably you have identified all the fuse or circuit breaker positions (see the chapter entitled "When Your Lights Go Out"), so this should take only a moment. Don't merely loosen the fuse in its socket; unscrew it completely and place it on the fuse box. Inform the other members of the family present in the house as to just what you are doing, and what outlets, lights, etc., will be inoperative while you are doing it.

With the line presumably opened by the fuse or breaker, give it a double check with the Lightester. If the bulb of the latter doesn't light, you can proceed.
 
Protect the Kiddies

An insurance company recently reported that about 40,000 electrical accidents in the home occur yearly in the United States. Considering the total population of about 170 million and the astronomical number of electric circuits and appliances in daily use, the figure is not a very large one. The sad part is that many of the victims who are seriously injured or killed are children. The fault is not theirs, but the parents'. Better protection in most cases calls only for a little common sense; in others for very inexpensive expedients.

The report listed these "bad actors": 1) open-type baseboard outlets; 2) lamp and other loose cords on the floors; 3) toasters and other appliances left connected after use.

Growing children are naturally inquisitive. They'll pick up hair pins, nail files, knives, forks, spoons, etc., and start investigating outlets and appliances. The metallic objects being perfect conductors of electricity, trouble is inevitable. Children have been known to pull out the two attachment plugs connected to a duplex wall outlet and to stuff the latter full of pins. Some of them stopped growing right then; others were more fortunate and escaped with nothing more than a strong jolt that threw them clear.

When the young son of Frank Bellek of Chicago had a narrow escape of this kind, papa decided to make a recurrence impossible. He designed a duplex outlet with a revolving cap over each section that turns automatically when the plug is removed and completely covers the live contact springs. To reinsert a plug, you merely place the prongs in the slots in the cap, twist a quarter turn to the right, and press in. Bearing the appropriate name "No-Shok," this self-thinking outlet is truly an inspired contribution to life and safety. It is simple, inexpensive, easy to install. Millions have been sold and it has proved foolproof.

DON'T! Of all crazyy ways of getting electrocuted quickly, this one is probably the best . . or the worst. The hand holding a metal knife, which is poked into the toaster to loosen a piece of bread, is resting on the metal frame of the appliance, which in turn is resting on a grounded metal stove. Keep toaster on wood table, and keep knives, and such, out of it.
 
No different in size or appearance from a regular duplex outlet, a No-Shok can replace the latter in any box. It shouldn't take more than five minutes per outlet. Follow exactly the procedure given for the installation of a mercury switch. (See "Silent Switch Lets Baby Sleep.")

Open toasters, broilers, etc., are another story entirely. You just have to get into the habit of removing the wall plug and tieing the cord around the appliance when a meal is finished. If possible, put the toaster in a kitchen cabinet, and close the door or cover of the broiler, to discourage tampering by children who may be about.

Junior isn't the only one who needs to be indoctrinated with good electrical safety habits. With appalling carelessness, many an adult sticks a knife into a "live" toaster to free a piece of bread. The toast pops loose, and the adult usually pops up about three feet himself. This practice is dangerous even if the appliance is "off," because it really isn't completely off at all. The internal switch opens one side of the line and this cuts off the current. However, and this is a very big "however", the other side of the line is still connected to one end of the heating wires. See Figure 1. If you poke a knife into the toaster you can very easily touch the latter and when you do you'll know it!

Loose cords on the floor are a menace mainly to toddlers who are teething. Children at this stage bite anything they can reach. Witness the edges of a crib or play pen, which looks as if they have been attached   by   hungry   beavers.   An   infant crawling on the floor is sure to discover all the flexible wires for lamps, radio and television sets, fans, air conditioners, etc., and to try them for taste. If the insulation is thin to begin with, or has worn through in spots (see "Don't Let a Cord Tie You Into Knots"), vigorous chewing by baby may quickly bare the wires inside. Add a little "salty saliva to make the connection more conducting . .. the result is horrible to contemplate. Nowhere else does preventive maintenance pay off in better terms.

Want to save the life of someone in your family . . maybe yourself? Then do this every time before you allow anyone to put his fingers or a metal utensil of any kind into a toaster or other heat-type appliance with exposed elements. Also, store the toaster, when not in use, in a closet or on a shelf, out of   the   reach   of   children.

With the internal switch of a toaster "off," the line between the plug and point A is reasonably sale because it is isolated from the accessible heat-in? element. However, any point in the toaster between C and B can readily become "hot" in relation to a ground if the plug should be in the wall outlet the wrong way. Moral: Don't poke any metal utensils or hardware of any sort into your toaster!

In any household having a toddling child, it is usually necessary to clear all small objects off tables during baby's waking hours. If you don't do the job, he or she will. At night you can restore the room to its natural state. At the same time you remove the ash trays, flower pots, etc., also unplug the loose electrical cords and curl them out of sight. All you'll have to be concerned about then is baby cracking his head against a table, falling off a chair, getting wedged under the sofa, pulling the curtains   down   on   himself,   and   similar minor events.

Protection By and Against Grounding

Fixed wiring, and appliances, once installed properly, continue to work for years without developing or causing the slightest trouble. The same cannot be said of portable or semi-portable appliances and tools which contain motors and which therefore are subject to vibration and movement effects. In clothes washing machines these are further aggravated by the presence of soapy water, an excellent conductor of electricity.

To make use of the protective feature of grounding, you must know how circuits are grounded. Figure 2 shows a fundamental branch circuit such as might be found in any home. The white colored wire is uninterrupted throughout its length. At the meter, where the power lines enter the house from the street, this wire is thoroughly "grounded" by means of a connection to the nearest cold water pipe, which is a good "ground" because it is actually in contact with the earth for a considerable length. The primary purpose of this grounding is to provide a direct return path to the earth of accumulations of static electricity in the sky before and during a thunderstorm. Picked up by the long, exposed wires from the generating station, this static can and often does burn out power distribution systems. A heavy burst of static electricity takes the spectacular form of a bolt of lightning. Good grounding saves countless homes from serious damage. All overhead telephone wires are similarly protected, by "lightning arres-tors" with a ground connection; and all outside radio and television aerials are supposed to be fitted with equivalent devices.

Figure 2 In house circuits, one side of the power line is grounded to a pipe; grounded wire is continuous throughout.

Figure 3 When power wires are encased in BX or other types of metal cable, the metal sheath is also grounded and becomes a parallel conductor to white wire.
 
Figure 4 A Lightester (see chapter on Testers And Tools) will demonstrate that a circuit can be completed through grounded frame of an electrical outlet box.

IF the house is wired with metallic sheathed cable of one sort or another, this sheathing is likewise grounded. When wires are cut, the outer sheathing is clamped into holes in metal boxes containing switches, lamps, outlets, etc., and the continuity of the grounding circuit is thereby maintained. The white wire inside "BX" and other armored cable (see Figure 3) is thus actually part of the same common circuit as the outer armor. This is a very important but often overlooked fact, which some people find difficult to believe. If you want to be convinced, or need to convince others, a quick demonstration with the Lightester will do the trick conveniently and to your satisfaction. As shown in Figure 4, place one lead A in the shorter slot of a wall outlet. If the fixtures have been wired correctly, this is the "hot" or ungrounded side of the 115-volt power line. First touch the lead B to longer contact of the outlet, which is the grounded side of the line. The bulb will light, showing that the outlet and the bulb are both OK. Now, leaving A in the short slot, touch B to the center screw of the outlet's cover plate. If it is reasonably clean of paint, the bulb will light again, showing that the lamp circuit has been completed, to the grounded side of the line. It will also light if lead B is touched to any other grounded object, such as a water or gas pipe, a radiator or a heating register. Every metallic part of the water or heating system of a house is bound to be a good ground because of the interconnection of their various pipes and ducts.

DON'T! Bringing any connected appliance to the sink can mean danger. Never fill steam iron this way.

Figures 5 and 6 The two diagrams illustrate the wiring arrangement of a typical portable drill. The case of the usual drill is completely insulated from the wiring. Note that the drill works equally well with either position of plug.
 
Now let's consider a typical portable device and see how it behaves under normal and abnormal circumstances. The ¼-inch electric drill is a fine example because it is so widely used in the home, the shop and the garage for a variety of purposes. Figures 5 and 6 show it in simplified diagrammatic form. The motor itself is represented by a coil of wire, the switch by an interrupted line, and the metal frame or body by a heavy circle. The switch and the motor are connected in simple series and two wires A and B pass through the case and terminate in an attachment plug. The drill works equally well with the plug inserted in the wall outlet either way, as indicated in Figures 5 and 6. If the motor winding, the switch and the line cord are all normally well insulated from the case, the latter is "cold" from the electrical standpoint. Thus, if a person is using the drill in a garage, and is standing on the cement floor as shown in Figure 7, no part of the current in the drill passes to him, although his feet are in firm contact with the ground to which wire B is connected.

It is well known that motor-operated tools, especially portable ones that are knocked around a great deal, often suffer internal injuries. The insulation on some motor windings is rather thin, and can readily wear through if the tool is used frequently. Suppose that any worn part of the winding makes contact with the iron core on which it is wound. The core is part of the case, so a new connection C is established as shown in Figure 8. If the user plugs in the attachment plug and reaches for the drill, he will receive a surprise. Trace out the simple circuit and you'll see why. Current enters the drill from the hot side of the line through wire A, flows through the motor wire until it reaches the worn spot, bypasses from here to the metal case, through the arms and body of the user, through his feet and shoes in contact with the ground, and through the ground to make a complete path back to the grounded side of the power line. The switch on the drill doesn't even have to be on.

The severity of the shock depends on two main factors: 1) The condition of the skin. Clean, dry hands have a relatively high resistance and allow little current to pass through. Wet, dirty hands are much more conductive. 2) The effectiveness of the underfoot ground contact. Cement has a surprisingly low electrical resistance. The garage is almost sure to be close to a water pipe, so it is pretty well grounded. Cotton and woolen socks and ordinary shoes are good insulators if dry, and these items of clothing are what usually reduce the "shock" to a mere sting, which should be taken as a warning that the drill needs looking into.

Wafer Increases the Danger

Water on the floor enormously increases the danger, because it reduces the resistance of the floor itself, and, worse, that of the usually protective foot gear, if any is worn in the first place.   Ignorance of this fact was responsible for a particularly nasty fatality that occurred recently. A father and a young son washed the family car in the driveway of their home, in advance of shining it up. The boy, sloshing around in the water as all boys love to, reached for a power drill, which had been fitted with the usual polishing felt. The drill may not have even been defective. Water from the child's hands might easily have dripped into the case, making excellent contact with a hot connection inside. Brr . . cases like this give me the shakes.

Figure 7 A portable drill in normal operation has switch closed;  insulation protects user.

Figure 8 If motor winding should ground to case at point C, portable drill user is usually shocked because current will follow path through drill casing and through user's body to the ground and then back to the grounded power lead B as shown here.

Suppose that the partial grounding of the motor winding to point C occurred with the line plug reversed; that is, with A now grounded and B the "hot" side, as in Figure 9. What would happen to the user? As long as the switch is open, nothing. But the instant he closes the switch he establishes a good circuit from wire B, through the switch, through the section of winding between the switch and point C, and from there again through his body to ground.

Millions of small portable drills were bought by "do-it-yourself" enthusiasts, and numerous accidents occurred with them, before tool manufacturers got around to providing protection for them. This takes the form of a third wire in the flexible coil, with one end connected merely to the case and the other to any ground. In some drills the end of the ground wire is fitted with a threaded stud which is supposed to replace the cover plate screw of a duplex outlet; in others, it has a big spring clip, to clamp around BX or other metallic sheathing, or a nearby pipe. Newer tools now appearing on the market have their cords fitted with a three-prong plug which fits a new type of duplex outlet having three slots in a T-shaped formation. The two parallel prongs on the plug are the normal current-carrying connections; the offset third prong is for the grounding wire only. According to the National Electrical Code, all new power tools, workshop and laundry machines are supposed to have this three-wire system.

(For detailed instructions on installing new three-wire safety cords in older drills and similar tools, see the next section of this book, entitled "The Third Wire Is a Lifesaver.")

Figure 10 shows how a grounded case protects the user of any appliance. The ground wire, in effect hooked back directly to the grounded line B, has extremely low resistance, so much lower than that of the human body that it short-circuits the latter out of any circuit combination.

Protection Is Complete

Consider several very real accidental possibilities in Figure 10. Suppose wire A wears through at point 1, where it enters the case. It touches the latter. There is now a very low resistance path for the current to flow from wire A to point 1, to the case, all around the case, and out through the ground wire back to the grounded side of the line. This is a thorough short circuit on the power line, and will kick out the line fuse or circuit breaker almost instantly.

Figure   9 If grounded motor of the drill should have its line plug reversed, user will be safe—until he turns on the switch. He  will  then,  of course, be shocked.

Figure10 If metal case of the tool is well grounded with low-resistance wire, current flow under any accidental circumstances is confined between case and ground, and user does not surfer. If point 1 is grounded, line is short-circuited and fuse blows. If 2 is grounded, motor runs with switch open. If 3 is grounded, nothing will happen at all.
 
Suppose wire B touches against the case at point 3. If it touches without breaking off, the normal, safe operation of the tool is not affected, because this connection is grounded anyway! If it breaks off, and either touches or doesn't touch the grounded case, the circuit to the motor is merely opened and the tool won't run when the switch is closed.

Suppose the junction point 2 of the motor winding and the switch becomes grounded to the case. When the tool is plugged in it will start immediately, even though the switch is still off. The power circuit from A is completed from 2 through the grounded case back to the grounded side of the line. The user still feels nothing because no current passes through his body; it's all going through the low resistance grounded case and ground wire.

More About Grounding

A separate grounding wire can easily be added to any tool or appliance not so factory-equipped. Fasten one end under any convenient screw on the case, tape the new wire along the present flexible cord, and attach a clip on the other end. It doesn't do any harm to remind you that this end must be grounded somewhere to do any good. The extra wire should not be any smaller than the wire in the present cord.

A separate grounding wire, with a screw-on clamp to fit on a water pipe, has been provided with most washing machines of recent manufacture. This wire should be placed so that it cannot be damaged or torn loose by clothes baskets, jars of laundry bleach, or other heavy objects. Loss of this grounding connection is invariably the reason some machines become "hot" and bounce their users across the room.    (See section following.)
With some washers, the flexible rubber hose that goes to the cold water tap has a grounding wire woven into it. The machine thus is grounded automatically when it is hooked up.
 
Because water, gas and steam pipes are such good grounds, avoid contact with them when using any portable appliances. Certainly the worst place in this respect is the bathroom. With sickening regularity the newspapers report fatalities due to wet contact with exposed bowl heaters. A summer camper, a girl of 17, was killed recently when she tried to dry her hair with an electric dryer in a shower room. Radio and TV receivers of the AC-DC "hot chassis" type have shocked numerous occupants of bathtubs and have killed several children; all made the mistakes of twiddling the tuning or volume knobs with wet, soapy hands. Under more fortunate circumstances, the sets merely blew the fuses and plunged the bathrooms into darkness when the chassis made accidental contact with an exposed pipe or other fixture.

If electronic entertainment in the bathroom is important, at least make certain that the equipment is of the full transformer type. Better still for the purpose is a battery-operated transistor portable.

In the kitchen, get the family into the habit of keeping connected appliances away from the sink. One woman learned what happens when an electric frying pan is immersed in sudsy water for cleaning, with the plug still in the socket! She recoiled suddenly, and gave herself a pretty thorough bath. Less funny was the experience of a mother who tried to give a six-month-old infant a quick cleaning off in the sink. Flailing its arms, the child pulled in a nearby toaster. Still connected, its exposed heating wires made a perfect return path to ground through the water. The baby was killed. ·

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