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When The Lights Go Out

—the fuses or circuit breakers have been overloaded. The only cure is  to  lighten  the  load,  not to  invest in  larger  protective  devices

Standard "plug" fuses have bases like lamps, and screw into receptacles in "cut-out" box. Keep a record on cover of latter of house circuits controlled  by particular fuses  to ease  replacement.

"Cartridge" type fuses have exposed metal end caps, which fit tightly in spring clips in cutout box. Keep spares in latter. CAUTION: Even if fuse is blown out end cap on side to meter is still "hot."
 
If you have a headache, sometimes you can get temporary relief by swallowing a couple of aspirins. After the effect of the pills wears off, the headache may still be with you. If you feel so badly that you go to a doctor, he'll probably tell you that a headache is not an ailment by itself, but the symptoms of one.

To a large extent, the same goes for fuses. If fuses keep blowing out, merely replacing them with new ones is no cure for the overload somewhere in the house that is causing them to go "pfft." And replacing the original fuses with others of higher amperage rating is about as sensible as looking for a gas leak with a candle.

In some homes, in which no new heavy-current appliances have been added recently and everything is working satisfactorily, a fuse may go dead without apparent reason, and putting in a new one of the same rating restores operation to normal. In cases of this kind the original fuse itself was probably faulty. It may not have burned out at all, but merely developed an internal open circuit. The fuse wire may have become brittle and then broken under the influence of vibration from a passing truck, a slamming door, etc. I have examined many fuses that looked perfectly good yet showed positively and unquestionably as complete "opens" when given a continuity check.

To remove a suspected cartridge fuse, first kill power by turning off main switch (have a flashlight handy if room is dark), then pry out with wooden stick. Turn on switch ii light is needed during testing operation. Be sure to turn it off again  before attempting to insert the new fuse.

Sometimes a fuse definitely blows out, and replacing it restores normal conditions. The burn-out may well have been due to a momentary short circuit which cleared itself, at least for the time being. For instance, a few strands of the flexible wire inside a cord for a floor lamp, a TV set, a fan, etc., might have worked against themselves because the cord has been stepped on a lot or otherwise abused. Enough current may have flown across these wires, during a second or so, to heat them and the fuse in the same circuit to the melting point. A new fuse holds, although the cord remains potentially dangerous.

Sometimes the touching wires, instead of flaring open, weld themselves together. New fuses then burn out as quickly as you put them in. Actually, it is better for this to happen, as then you know something is definitely haywire someplace and you are forced to go looking for it.

As a general practice, when troubleshooting the house power circuits, allow yourself one new fuse as a replacement for a blown unit. If this pops off, start shooting!

Heavy Starting Loads vs. Fuses

Blown fuses did not become a problem in most households until two highly desirable machines appeared on the market: first the clothes washer, •which eliminates the most onerous of family chores; and then the air conditioner, which enables the family to sleep at night. The thing that puzzles owners of these machines is that they take less power than many other appliances that have been used for years without trouble. For example, a clothes washer takes only about 375 watts in normal operation and perhaps 800 or 1000 during a fast spinning cycle; a typical room air conditioner takes 800 to 1000 watts steadily. Compare these figures with the power consumption of a hand iron, 1000 watts; a bathroom heater, 1130 watts; a toaster, 1010 watts; a coffee maker, 830 watts; a frying pan, 1160 watts. If plugging in a 1000-watt iron doesn't bother the fuses, why does a 1000-watt air conditioner make them jump out of their skins?

The answer lies in the nature of both the fuses and the power load. An ordinary fuse, the kind you screw into a socket in a box in the basement, consists merely of a piece of wire of rather low melting point. As you probably know, electric current flowing in any wire must push its way through, and in so doing generates some heat. The higher the current, the higher the heat. For fuse purposes, an alloy wire is used that melts quickly if the current exceeds a certain value; the fuse wire is thin for low values of current and thick for high values. There isn't, and indeed there shouldn't be under ordinary circumstances, much leeway in fuse ratings. A fuse marked 15 amperes should not burn out with 14 amperes going through it, but it should be noticeably warm at 15 amps, pretty hot at 16 and just about melting at 17.

An 830-watt coffee maker plugged into a kitchen outlet takes about 7 amperes of current. For a fraction of a second after the appliance is turned on it takes more, but the interval is such a short one that the effect can be ignored for all practical purposes. A load of 7 amperes obviously places little strain on a 15-ampere fuse, -which is the normal size for "branch circuits" in a home.

Quick test with Handitester shows condition of fuses. A good fuse registers 0 resistance, a blown one shows infinite resistance or open circuit. Check your fuses regularly and discard all defective ones.
 
A standard size clothes washer is rated at 375 watts. While running it takes between 6 and 7 amperes of current. (For the arithmetic of volts, amperes and watts, see the section entitled "Power Is What You Pay For.") A 15-amp fuse should therefore afford plenty of latitude. It would, except for an important physical consideration.

Into a large steel tub you dump eight or nine pounds of clothes and then add water almost to the top. If this loaded tub were out of the washer, I doubt if you'd be able to carry it more than a few feet without straining a muscle or two. This is the stationary, dead weight the motor in the machine must get into motion. When you turn the dial to "wash," the power circuit to the motor closes. During an appreciable part of the first second following, the motor struggles to develop the necessary torque, and in so doing draws 25, 30 or 35 amperes of current from the line. If the line is protected by an ordinary 15-ampere fuse, the motor usually doesn't even have a chance to turn over once; the fuse merely goes "pfft," as it should with an overload of 100% or more, and you're stuck with a washer full of dirty clothes.

Appliance dealers and customers alike developed high blood pressure before they discovered a vital bit of information in the instruction sheets that came with washers. This stated quite clearly that ordinary fuses cannot be used, but must be replaced with special ones of the "slow-blow" type, which cost only a few cents more. These fuses are designed specifically to handle motor loads. They get a bit warm during the starting period, but they hold up long enough to permit the motor to overcome the inertia of the tub and to get it rolling. The motor current then drops quickly to its normal running value 6 or 7 amperes. A slow-blow fuse rated at 15 amperes does the job.

The time delay in slow-blow fuses is pretty delicately adjusted to give a safe balance between convenience and protection. If the tub is overloaded with a few extra towels and a bedsheet, and is just so heavy that it locks the motor, the continuing flow of 30 or 35 amperes kicks out the fuse in a second or so. If it didn't, the motor and the wiring to it would start to smolder. Similar stalling sometimes occurs in slightly overloaded machines that have a fast spin cycle for drying the clothes. If slow-blow fuses of the recommended size for a particular washer blow out, you can be pretty sure that the tub merely is being piled too high.

Slow-blow fuses are so important to the satisfactory operation of washers that some manufacturers tape an actual fuse to the prongs of the attachment plug of the machine, as an inescapable means of calling the buyer's attention to it.

Exactly the same problem presents itself with air conditioners, except that it is more acute because these machines usually contain two motors: a pretty big one for operating a stiff compressor, through which the refrigerating liquid flows; and a smaller one, for a fan that pushes the cold air out. The starting current of a medium size cooler working on 115 volts can be as much as 50 amperes. A slow-blow fuse, of a size depending on the running rather than the starting current, is again .the answer.

Actually, fusing is a relatively minor problem with air conditioners. Much more serious trouble is caused by the steady hour-after-hour flow of the running current through house wiring that is too thin to handle it without heating up. (See the section entitled "Is Your Wiring Adequate for Your Load?").

The motors used with home workshop power tools range between ¼ and 1 horse-power and they, too, have fairly high starting currents. However, except in the case of lathes (and then not always), the load is not applied until the tool reaches full operating speed, so blown fuses are not too frequent. A slow-blow fuse in the shop line is the cure if one is needed.
Types of Fuses

Most of the fuses found in homes are of the "plug" type. This term is somewhat misleading, as plug fuses have threaded bases exactly like those of lamps, and they screw into threaded sockets. Fuses that really plug in are called "cartridge" fuses. These have a fiber body and metal end caps, and fit into spring clips. Slow-blow fuses, which are sold under a variety of trade names, have screw bases like ordinary plug fuses and can be distinguished from the latter by their more complicated internal spring mechanism.

Plug fuses can be removed and replaced with little danger of shock, because the ends are completely insulated and are not part of the circuit. Cartridge fuses, however, must be treated with great respect because of the exposed end caps. Even if such a fuse is blown out, the end on the power line side is still plenty "hot." The picture on page 65 shows a safe method of handling cartridge fuses.

Cutaway view shows internal construction of Westinghouse thermal type circuit breaker, a fine safety device. Contacts are open. When handle is pushed to right, circuit is restored and handle is latched.

Even a child can operate the circuit breakers used to protect electrical circuits. Double bank of 14 breakers (Westinghouse) is completely safe because all "hot" connections are inside wall box.

Testing fuses for condition is very simple. They are either open or closed. With the Clicktester, you will hear a loud click if the fuse wire is OK, or nothing if it is gone. With the Handitester, a good fuse shows as zero resistance; a dead one doesn't even move the needle of the meter. If intermittent contact inside a fuse is shown by an irregular clicking or a fluctuating meter needle, chuck it out. Fuses are so cheap that it doesn't pay to retain questionable ones.

This heavy-duty two-pole circuit breaker is intended for use on 3 wire. 115/230 volt circuits. A Westinghouse "De-Ion" type, it is rated at 50 amperes. Breakers are more convenient than fuses.

Chart of Fuse Positions

The "cut out" box in most homes contains six fuses; more in many newer houses. It is highly advisable to know which fuses control which outlets and lights all through the dwelling. Have an assistant turn on all the lights in one room at a time, and also activate the wall outlets with portable lamps, a radio set, etc. Start removing fuses and let the assistant shout down or stamp on the floor when the juice goes off. Make up the data in chart form and cement or tape it to the cover of the fuse box. Also, keep a handful of spare fuses, of the right sizes for your power installation, within easy reach of the fuse box. You'll congratulate yourself on your foresight in this regard the very first time a circuit goes dead unexpectedly, as it always does.

Circuit Breakers

In all but the lowest price brackets, the tendency in new home construction is now definitely toward the use of circuit breakers rather than fuses for protection against excessive current surges. A circuit breaker has a handle like a switch and looks very much like one; it is in fact a self-tripping switch that goes open when the current passing through it exceeds its rated value.

The breakers now coming into home use work on either a thermal or a magnetic effect, or a combination of the two. The thermal type employs a bi-metallic strip which flexes and trips one or more sets of spring-loaded contact points when the rated current value is passed. The magnetic type contains an electromagnet which does the same job. Most breakers incorporate a time delay feature like that of slow-blow fuses, and for exactly the same reason.

When a circuit breaker trips open on an overload, it can be reset in an instant; you merely push the handle back up. If the overload is still on, it will trip again. Like a good switch, a breaker will last a long time and rarely if ever will require replacement.

Because circuit breakers cost from 4 to about 25 times more than fuses, many   people   have   gotten   the   impression that circuit breakers in general have magical properties and offer more protection than fuses do. This is not so. An overload that trips a $2.50 breaker will also burn out a five-cent fuse, and just as quickly and thoroughly. The most obvious advantage of breakers is convenience. A far more important feature, which is not as widely appreciated as it should be, is that in many cases they prevent a thoughtless homeowner from deliberately overloading his power lines.

New circuit breaker has screw base and can replace conventional fuses in regular cutout box without requiring changes in wiring. When current overload exceeds rating of breaker, center button pops up and circuit is opened. To reset breaker after overload is cleared, it is only necessary to press button down. This type of protective device is especially useful in homes and shops where occasional motor overloads   at   times   occur.
 
Consider a "standard" house having branch circuits protected by regular 15-ampere plug fuses. A new table-top broiler arrives one day and all the members of the family gather round while it is unpacked, admired, and then, of course, plugged in to see how it works. Many such broilers take pretty close to 15 amps all by themselves. If current is being carried on the same line for lights or other purposes, there is a very good chance that the 15-amp fuse will evaporate. Great disappointment registers on the faces of mother and the kids. So what does pop do? Nine times out of ten, he will not resist the temptation to replace the 15-amp safety valve with a 20-amp plug. Result: the broiler goes on and his reputation as Mr. Fix-It is saved. What happens to the power line is another story. Sooner or later this practice leads to disaster.

If the house is equipped with 15-ampere circuit breakers, the breaker feeding the broiler line will flip open on the overload just as the fuse did. But this breaker is permanently bolted into the distribution box, with its connections out of sight. There's nothing you can do to it except push the handle back to "on." Every time it trips open it is warning you that the broiler is just too much for that line. You might swear at it a little, but the sooner you realize the significance of the tripping of a circuit breaker, the longer will your house last.

I have heard people say they don't like circuit breakers because "they don't allow any flexibility in operating certain lines in the house." This is cockeyed reasoning of the worst sort. The fact that breakers do not permit any such "flexibility" is the greatest argument in their favor. Probably 90% of all actual cases of fires, charred wiring, sluggish air conditioners and freezers, etc., would not have occurred at all if uncorruptible breakers had been used instead of easily "fixed" fuses, which are a danger in ignorant hands.

In this section the value of 15 amperes has been used in describing fuse and breaker protection for branch circuits in a house. This is the safe allowable carrying capacity of No. 14 wire, the size most commonly used in homes. However, much greater values are permissible with heavier wires, as explained in the section "Is Your Wiring Adequate for Your Load?" An overload is an overload, regardless. ·

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