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Is Your Wiring Adequate?

Ask your utility company to inspect it.  Insufficient wiring  causes faulty operation of appliances, reduced voltage and wasted power

Fig. 1. Label on obsolete main fuse box.

Thousands of new homes and apartments built each year are found to be electrically obsolete after only a couple of years of occupancy. When new appliances are acquired, the owners must spend large sums on additional wiring, and in some cases they are forced virtually to rip the old wiring out and to replace it with adequate lines.

"Inadequate"  wiring creates a double problem:   1)  It reduces the normal line voltage, often to the point where appliances cease to work satisfactorily; 2) It becomes overheated, and can readily start a fire in the  home.   Lights   go   dim,   TV  pictures shrink, a broiler doesn't cook the food in it, an air conditioner can't be used at all ... all because of inadequate wiring.   According to the Joint Industry Board of the Electrical Industry, four out of five homes and apartments in the great City of New York are insufficiently wired for appliances now found in them. The situation in other places is so bad that municipal ordinances are being drawn up which force the users of   heavy-current   machines   to   protect themselves.   For   instance,   in   Memphis, Tenn., appliance dealers are required to report to the city the sale of any device rated at 1,000 watts or more. The city then inspects the home of the purchaser to see that it is wired properly. Louisville, Ky., under an existing electrical code, can require property owners to install proper wiring or lose electrical service. In addition,  the  city  is  considering  a  new  law patterned after the one in effect in Memphis, which would require buyers of appliances to prove they have the necessary circuits   to   carry   the   additional   load. Affected would be air conditioners, room heaters,   kitchen   ranges,   roasters,   friers, broilers, garbage disposal units, large ironing  machines,   clothes   driers   and   dishwashers.
 
The National Electrical Code, which forms the basis for practically all local electrical codes and ordinances, is a standard of safety. It deals primarily with the materials and methods of installation of wiring systems. However, these various codes cannot provide against the possibility of the wiring system becoming overloaded because of major additions to the home's electrical equipment. Code authorities recognize this limitation, and call attention to it in the introduction to the National Electrical Code, which states: "... an installation reasonably free from hazard, but not necessarily efficient or convenient. Good service and satisfactory results will often require larger sizes of wire, more branch circuits and better types of equipment than the minimum which is specified here."

Many people ask, "Why doesn't the local power company make sure the wiring in a house is sufficient? After all, the company is in the business of selling electricity and it's to their advantage to have a lot of appliances running properly."

The answer briefly is that your home is your castle, and what you do in it is your responsibility. If you chose to set it on fire by disregarding the limitations of its electrical system, the loss is yours. It may be yours alone, insurance notwithstanding, if subsequent investigation proves that your wiring was illegal and improper. Naturally, the utility companies don't like to lose customers, so many of them offer free wiring advisory service. Call the office of your local utility and find out. Note that this service is only advisory. The utility's actual responsibility ends with the power wires where they fasten to your house. The service entrance wires and everything else then depend on you. (The electric meter is the property of the utility but in (Continued on page 26)

Basic Capacity: 24,000 watts

Basic Capacity: 14,500 watts

Basic Capacity: Probably 3,600 watts

Fig. 2. Compare your main fuse box or circuit breaker box with the diagrams below. If it is the type shown at left, it is inadequate for present-day electrical loads. Consult your power company engineer.

Typical 30 Amp. Fuse Type Main Switch

Typical  60 Amp. Fuse Type Combination Main Switch and Branch Circuit Panel

Typical 100 Amp. Fuse Type Combination Main Switch and Branch Circuit Panel

Typical 30 Amp. Combination Main Breaker and Branch Circuit Panel

Typical 60 Amp. Combination Main Breaker and Branch Circuit Panel

Typical 100 Amp. Main Breaker

This will supply: Lighting and a Few Plug-in Appliances.

This will supply: Lighting and Plug-in Appliances—Electric Range — Water Heater.

This will supply: Lighting and  Plug-in Appliances—Electric   Range — Water Heater PLUS any Major Appliances*

With possible exception of Central Air Conditioning or Electric House Heating.

Typical Wattages of Some Lights and Appliances Normally Connected to General Purpose or Plug-in Appliance Circuits effect it becomes part of the permanent wiring installation in the home.)

**Each time the refrigerator starts it takes several times this wattage for an instant.
 
LIGHTING                                                                  watts

Ceiling or Wall (each bulb)                                            40-150
Floor Lamps  (each)                                                     1 50-300
Fluorescent Lights leach tube)                                       15-40
Pin-to-Wall Lamps                                                       50-1 50
Table lamps (each)                                                       50-1 50
Ultra Violet Lamp                                                         385

APPLIANCES                                                            watts

Baker (portable)                                                           800-1000
Bottle Warmer                                                              95
Broiler-Rotisserie                                                          1320-1650
Casserole                                                                     1 350
Clock                                                                           2
Coffee Maker or Percolator                                          440-1000
Coffee Grinder                                                             1 50
Corn Popper                                                                1 350
Deep Fat Fryer                                                             1 350
Egg Cooker                                                                  500
Electric Bed Cover                                                       200
Electric Fan (portable)                                                  100
Electric Roaster                                                            1650
Food Blender                                                               230-250
Hair Dryer                                                                    235
Hand Iron (steam or dry)                                              1000
Heating Pad                                                                  60
Heated Tray                                                                 500
Ice Cream Freezer                                                        115
Ironer                                                                           1650
Knife Sharpener                                                           103
Lawn Mower                                                               250
Mixer                                                                           100
Portable Heater                                                            1000
Radio (each)                                                                 100
Record-Changer                                                           75
Refrigerator*.*^                                                           1 50
Sandwich Grill                                                              660-800
Saucepan                                                                     1000
Sewing Machine                                                           75
Shaver                                                                          12
Skillet                                                                           1100
Television                                                                     300
Toaster (modern automatic)                                          up to 11 50
Vacuum Cleaner                                                           .125
Ventilating  Fan  (built-in)                                              140
Waffle Iron                                                                   up to 1100
Warmer (Rolls, etc.)                                                     100
Waxer-Polisher                                                            350

One each (230 or 240 volt) for:                                    watts

Electric Clothes Drier                                                    4500
Electric Range                                                              8000-16,000
Electric Water Heater                                                   2000-4000
Room Air Conditioner* (½ or ¾ ton). . .                       1200-1600
Water  Pump*                                                              700-1 500
One each (115 or 120 volt) for:                                    watts
Automatic Washer*                                                      700
Built-in Bathroom Heater                                              1000-1500
Dish washer-Waste-Disposer                                       1 500
Electrostatic Air Cleaner                                               60
Home Freezer*                                                            350
Mechanism for Fuel-fired Heating Equipment* . .          800
Room Air Conditioner* (1/3 ton)                                  750
Summer Cooling Fan*                                                  250-750
Waste-Disposer alone* (without Dishwasher). . .          500
Water Pump*                                                               700
Workshop or Bench* (Total wattage will vary)

*The wattage of motor-operated equipment will vary, depending on the tile of the motor. Individual circuits are necessary, however, in order to avoid frequent "blackouts," poor TV and radio reception, constant dimming or flickering of lights when the equipment if operating; to assure continuity of service from such devices as the home freezer and the heating plant, and to permit the u«e of plug-in and major appliances at the same time.

GENERAL PURPOSE CIRCUITS

For lighting and general use in living and bedrooms; lighting only, in kitchen, laundry, dining area.

Most homes built before 1940 still rely on one or two 15 ampere General Purpose Circuits for all lighting and appliance use. In many instances, even certain major appliances have been plugged in on these poor, overworked wires.

To convenience outlets only (no lights), in kitchen, laundry, dining area —seldom found in homes built before 1940.

Most homes built since 1940 have one or more Plug-in Appliance Circuits, but some do not. And, often, the one Plug-in Appliance Circuit has since been forced to substitute as a Major Appliance Circuit, to serve some new appliance, like automatic washer, dishwasher, or home freezer. Then, it .becomes overloaded each time it is shared with any of the plug-in appliances shown on the list at left.

Each of the major appliances and other equipment listed at left should have its own, individual branch circuit, in order to do its best work. If you have an electric range, water heater or clothes drier, you are sure to have a separate circuit for each one. They could not have been installed otherwise. However, in many homes, other major appliances have been connected to General Purpose or Plug-in Appliance Circuits which were already carrying more than their share of lighting and plug-in equipment.

In most older homes, the electric service entrance was planned to accommodate only lights and a few plug-in appliances, such as a toaster or an iron in the kitchen, radio sets in various rooms, and a portable vacuum cleaner. In such homes, certain newer machines cannot be used at all unless the entire service entrance is replaced by a larger one. Installing larger fuses than the present ones is no solution to the problem, and is an extremely dangerous and foolish practice.

Fig. 3. As shown in diagram above, split outlet wiring permits use of two heavy-current appliances.

Fig. 4. Actual Diameters of Typical Sizes of Copper

A common mistake made by many people is to assume that the service entrance is "adequate" merely because it is "three-wire." Most homes built since about 1940 have three-wire service, which can accommodate an electric range and a water heater. However, few of them have three wires that are big enough to bring in sufficient electricity for today's needs. Wire of the No. 2 size is recommended as a minimum. Remember that you pay only for the electricity you use, no matter how large the service entrance may be. Therefore, it pays in the long run to have it made big enough to permit future expansion. It can easily be too small, but it can never be too big.

0               1     2            4        6          8          10      12     14            

Fig. S.           Properties            Of Copper       Conductors*      

                                                Ohms Per         Bare                    Concentric
Size of           Circular               1000 Feet        Conductor           Lay Stranded
Conductor     Mils                     25°C-77°         F            Diameter—    Conductors
AWG                                       Bare Conductor             Inches    No. of Wires
14                 4,107                  2.575               .064                    Solid
12                 6,530                  1.619               .081                    Solid
10                 10,380                1.018               .102                    Solid
8                   16,510                .641                 .129                    Solid
6                   26,250                .410                 .184                    7
4                   41,740                .259                 .232                    7
2                   66,370                .162                 .292                    7
1                   83,690                .129                 .332                    19
0                   105,500              .102                 .373                    19
00                 133,100              .081                 .418                    19
From National Electric Code-1953.

It is difficult and risky for a layman to determine the actual size of the service entrance wires, as this usually means poking around the circuits while they are alive. Really the safest and cheapest thing to do is have the job done by a representative of the power company or by a local electrical contractor.

As a minimum, examine the main fuse box or circuit breaker box and look for an Underwriters' Label. If it is marked "Form 30," the service entrance is definitely obsolete. See Fig. 1, page 22. If the label has disappeared or if it has a different form number, compare your main panel with Fig. 2, page 23, and you'll get a fair idea of what you have.

According to modern standards, the service entrance in a 1000 square foot home should provide at least 4,500 watts for lighting and plug-in appliances (more in larger homes), plus any of the following permanently connected major appliances which are already in or are likely to be installed in the near future:

Automatic Washer                                                        700 watts
Built-in Bathroom Heater (how many?) each                 1000-1500 watts
Dishwasher                                                                   1500 watts
Clothes Drier                                                                45OO watts
Electric Range                                                              8000-16,000 watts
Water Heater                                                               2000-4000 watts
Electrostatic Air Cleaner                                               60 watts
Home Freezer                                                              350 watts
Mechanism for Fuel-Fired Heating Plant                        800 watts
Room Air Conditioner, ½ ton                                        750 watts
Room Air Conditioner, ¾ ton                                        1200 watts
Water Pump                                                                 700 watts
Waste Disposer                                                            500 watts

What can be done about inadequate entrance service and equipment? The power company engineer or electrical contractor will probably recommend one or more of the following:

(Continued on page 29)

Fig. 6    ALLOWABLE CURRENT-CARRYING CAPACITY, IN AMPERES, OF COPPER CONDUCTORS*

Based on room temperature of 3O°C (86°F)

Fig.·7        INSULATION TABLE

Insulation                                  Type                Maximum         Suitable For
Letter                                                               Operating
                                                                        Temperature
Code Rubber                           R                      6O°C(I4O°F)  General Use
Moisture-Resistant Rubber       RW                  6O°C (UO°F)  General Use
                                                                                                And Wet
                                                                                                Locations
Latex Rubber                           RU                   60°C(140°F)    General Use
Moisture-Resistant
Latex Rubber                           RUW               60°C(140°F)    General Use
                                                                                                And Wet
                                                                                                Locations
Heat-Resistant Rubber              RH                   75°C(l67°F)     General Use
Thermoplastic                           T                      60°C{I4O°F)   General Use
Moisture-Resistant
Thermoplastic                           TW                  60°C(140°F)    General Use
                                                                                                And Wet
                                                                                                Locations
Weatherproof                           WP                  80°C(176°F)    Open Wiring
                                                                                                By Special
                                                                                                Permission
'From National Electric Code-1953.

Fig. 8. This illustrates recommended allowable maximum voltage drops in a typical house wiring system.

1) Replace   present   service   entrance wires with larger ones.

2) Replace   outmoded  fuse  or  circuit breaker box with one of larger capacity probably a minimum of 100 amperes.

3) Retain present main panel as part of the service equipment and install a second main panel to increase the total capacity.

4) Replace old meter with a newer one.

This .is only the beginning,  of course. You have to work out from the fuse boxes into the branch circuits feeding the various parts of the house.

In some homes, a bad case of overloaded circuits can be relieved by having the automatic washer, dishwasher, freezer and other major appliances put on individual circuits. This may require some chopping of walls for the new wires and outlets, but it's worth the trouble. By the time a house needs new wiring it probably can also use a new paint job, and the two operations can be combined.

A modern and efficient method of increasing circuit capacity is to have one or more three-wire circuits installed, to serve convenience outlets into which you want to plug more than one high-wattage appliance at a time; for instance, a toaster and a coffee pot, at breakfast time, or a broiler and an iron, to permit a woman to press clothes while food is cooking. As shown in Fig. 3, page 26, this arrangement divides the openings of each convenience outlet   between   two   different   circuits, greatly reducing the chance of overloading. The wires should be No. 12 in size.

Three-wire circuits also permit you to control one section of an outlet from a wall switch, while leaving the other section permanently alive for any plug-in purpose.

Wires and Voltage Drop*

The "circular mil" is the unit of measurement of the cross-section of wire used in electrical practice. One circular mil, abbreviated cir mil or cm, is the area of a circle 1/1000 of an inch in diameter. If the diameter of the wire in mils is known, the figure is simply squared and the result is circular mils. Because electrical workers rarely if ever have occasion to put a micrometer on copper wires, and because the cm numbers are very large and unwieldy even for small wires, this method of designation is rapidly falling out of favor. Instead, much more convenient one- and two-digit numbers, forming the "American Wire Gauge," or "AWG," are used in practical work. The accompanying table, Pig. 5, page 26, gives the relationships between gauge numbers, circular mils, actual wire diameters, etc. The AWG is the same as the  "Brown and  Sharpe  Gauge,"  or "B & S." Fig. 4, page 26, shows the actual full-size diameters of typical power wires from No. 14 through No. 0.

*Part of the material in this section has been abstracted from the "Westinghouse Home Wiring Handbook," Westinghouse Electric Corp., Pittsburgh, Pa.

}DISTANCE     IN     FEET}

Conductor Size Based on Voltage Drop (115 Volt—2% Drop)

Fig. 9. With the aid of this chart and those on pages 28-29, you can determine what size wire you need.

The conductor sizes given in Fig. 6, page 27, are based on current-carrying capacity of wire having type "R" insulation, which is a rubber compound, and the wires are assumed to be in raceways or cables. There are many varieties of insulation, but the ones listed in Fig. 7, page 28, are the ones in common commercial use.

Each type of conductor insulation affords a given maximum safe-operating temperature. If this "safe" value is exceeded for any considerable length of time, the insulation will deteriorate rapidly; under heavy overload conditions it can readily melt or burn off, permitting the copper wires to touch each other or the grounded cable in which they might be encased. If the fuses or circuit breakers are functioning normally, they will open and cut off further current.

Fig. 10.    Conductor Size Based on Voltage Drop (230 Volt—-2% Drop)

Fig. 11.    Conductor Size Based on Voltage Drop (230 Volt—2½% Drop)

Fig. 12.      Conductor Size Based on Voltage Drop (230 Volt—1 % Drop)
 
The conductors of a wiring system should be of sufficient size not only as a safeguard against overheating, but also to restrict voltage drop. It is impractical to avoid all drop, but it can and should be held to reasonable proportions.

The recommended allowable maximum voltage drops in the various portions of a typical house electrical system are shown in Fig. 8, page 28. It is good practice to have the conductors of such a size as to keep the drops within the percentage limits indicated. The heavier the wire chosen for a circuit, the lower the voltage loss in it and the higher the voltage delivered to the appliance.

To determine if a conductor sized correctly for current-carrying capacity will also keep the voltage within allowable bounds, check against Figs. 9,10,11, pages 29 and 30, and 12, above. Each of these covers a specific type of feeder or circuit. Based on economical voltage drop, load in watts and length of the circuit in feet, the proper size of conductor can be selected readily. Here's a practical example of the use of the charts:

Situation: A 115-volt branch circuit carries 1500 watts (13 amperes) a distance of 75 feet. It is desired to keep within 2% voltage drop, or 2.3 volts. Will No. 12 wire, having a carrying capacity of 20 amperes, do the trick?

Answer: No. Fig. 9 shows that No. 12 will carry 1500 watts about 53 feet with a 2% drop. To find the right size, start at the 1500-watt line at the left, and run your finger to the right until you meet the vertical line coming up from the 75-foot mark at the bottom of the chart. The point of intersection is clearly on the heavy line marked 10, which is the number of the needed wire. ·

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