Chapter 11—Electricity

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1

Flow of Electric Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2

Electric Service Entrance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

Service Drop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

Underground Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Electric Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Two- or Three-wire Electric Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-6

Residential Wiring Adequacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-6

Wire Sizes and Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-7

Reducing Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-7

Wire Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-7

Wire Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-8

Types of Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-8

Flexible Cords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-9

The Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-9

The Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-9

Safety Suggestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-9

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10

Open Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10

Concealed Knob and Tube Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10

Electric Service Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10

Over-Current Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10

Circuit Breakers (Fuseless Service Panels) . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-11

Ground Fault Circuit Interrupters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-11

Arc-fault Circuit Interrupters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12

Fused Ampere Service Panel (Fuse Box) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12

Electric Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-13

Outlet Switches and Junction Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-13

Grounding Outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-13

Polarized Plugs and Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-14

Common Electrical Violations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-14

Excessive or Faulty Fusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-15

Cords Run Through Walls or Doorways and Hanging Cords or Wires . . . . .11-15

Temporary Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-16

Excessively Long Extension Cords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-16

Dead or Dummy Outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-16

Aluminum Wiring Inside the Home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-16

Inspection Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-16

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-17

Additional Sources of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-17

Figure 11.1. Utility Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

Figure 11.2. Entrance Head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

Figure 11.3. Armored Cable Service Entrance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Healthy Housing Reference Manual 1

Contents
Figure 11.4. Breakers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Figure 11.5. Thin-wall Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4

Figure 11.6. Electric Meter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-5

Figure 11.7. Typical Service Entrance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-5

Figure 11.8. Grounding Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-6

Figure 11.9. Grounding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-6

Figure 11.10. Three-wire Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-7

Figure 11.11. Two-wire Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-7

Figure 11.12. Wire Markings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-8

Figure 11.13. Armored Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-9

Figure 11.14. 200-Amp Service Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-11

Figure 11.15. External Power Shutoff and Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-11

Figure 11.16. Ground Fault Circuit Interruptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12

Figure 11.17. Arc Interrupter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12

Figure 11.18. Types of Fuses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-13

Figure 11.19. Appliance Ground and Grounded Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-14

2 Contents
'“To electrize plus or minus, no more needs to be known

than this, that the parts of the tube or sphere that are

rubbed, do, in the instant of the friction, attract the

electrical fire, and therefore take it from the thing rubbing;

the same parts immediately, as the friction upon them ceases,

are disposed to give the fire they have received to any body.”

Benjamin Franklin 

Franklin’s Discovery of the Positive 

and Negative States of Electricity, 1747

Introduction

Two basic codes concerned with residential wiring are

important to the housing inspector. The first is the local

electrical code. The purpose of this code is to safeguard

persons as well as buildings and their contents from

hazards arising from the use of electricity for light, heat,

and power. The electrical code contains basic minimum

provisions considered necessary for safety. Compliance

with this code and proper maintenance will result in an

installation essentially free from hazards, but not

necessarily efficient, convenient, or adequate for good

service or future expansion.

Most local electrical codes are modeled after the National

Electrical Code, published by the National Fire

Protection Association (NFPA). Reference to the “code”

in the remainder of this chapter will be to the National

Electrical Code, unless specified otherwise [1]. 

An electrical installation that was safe and adequate

under the provisions of the electrical code at the time of

installation is not necessarily safe and adequate today. An

example would be the grounding of a home electrical

system. In the past, electrical systems could be grounded

to the home’s plumbing system. Today, many plumbing

systems are no longer constructed of conductive material,

but are made of plastic or polyvinyl chloride-based

materials. Today, the recommendations for grounding a

home electrical system are to use two 8-foot by 5/8-inch

copper ground rods. These must be spaced 6 feet apart

and be connected by a continuous (unbroken) piece of

copper wire (the size of this wire corresponds to the size

of the system main). It is also highly recommended that

the system be grounded to the incoming water line if it is

conductive or to the nearest conductive cold water

supply line. Hazards often occur because of overloading

wiring systems or usage not in conformity with the code.

This occurs because initial wiring did not provide for

increases in the use of electricity. For this reason, it is

recommended that initial installations be adequate and

that reasonable provisions for system changes be made

for further increases in the use of electricity.

The other code that contains electrical provisions is the

local housing code. It establishes minimum standards for

artificial and natural lighting and ventilation, specifies

the minimum number of electric outlets and lighting

fixtures per room, and prohibits temporary wiring except

under certain circumstances. In addition, the housing

code usually requires that all components of an electrical

system be installed and maintained in a safe condition to

prevent fire or electric shock.

Chapter 11: Electricity

Healthy Housing Reference Manual 11-1

Ampere—The unit for measuring intensity of flow of electricity. Its symbol is “I.”

Bonding—Applies inert material to metal surfaces to eliminate electrical potential between metal components and

prevent components and piping systems from having an elevated voltage potential. 

Circuit—The flow of electricity through two or more wires from the supply source to one or more outlets and back to the

source.

Circuit breaker—A safety device used to break the flow of electricity by opening the circuit automatically in the event of

overloading or used to open or close the circuit manually.

Conductor—Any substance capable of conveying an electric current. In the home, copper wire is usually used.

• A bare conductor is one with no insulation or covering.

• A covered conductor is one covered with one or more layers of insulation.

Definitions of Terms Related to Electricity
Flow of Electric Current

Electricity is usually created by a generator that converts

mechanical energy into electrical energy. The electricity

may be the result of water, steam, or wind powering or

turning a generator. The electricity is then run through a

transformer, where voltage is increased to several hundred

thousand volts and, in some instances, to a million or

more volts. This high voltage is necessary to increase the

efficiency of power transmission over long distances. 

This high-transmission voltage is stepped down (reduced)

to normal 115/230-volt household current by a transformer

located near the point of use (residence). The electricity is

then transmitted to the house by a series of wires called a

service drop. In areas where the electric wiring is underground,

the wires leading to the building are buried in the ground.

For electric current to flow, it must travel from a higher

to a lower potential voltage. In an electrical system, the

11-2 Electricity

Conductor gauge—A numeric system used to label electric conductor sizes, given in American Wire Gauge (AWG). The

larger the AWG number, the smaller the wire size.

Current—The flow of electricity through a circuit. 

• Alternating current is an electric current that reverses its direction of flow at regular intervals. For example, it

would alternate 60 times every second in a 60-cycle system. This type of power is commonly found in homes.

• Direct current is an electric current flowing in one direction. This type of current is not commonly found in

today’s homes.

Electricity—Energy that can be used to run household appliances; it can produce light and heat, shocks, and numerous

other effects.

Fuse—A safety device that cuts off the flow of electricity when the current flowing through the fuse exceeds its rated

capacity.

Ground—To connect with the earth, as to ground an electric wire directly to the earth or indirectly through a water pipe

or some other conductor. Usually, a green-colored wire is used for grounding the whole electrical system to the earth. A

copper wire is usually used to ground individual electrical components of the whole system. (The home inspector should

never assume that insulation color wiring codes have been used appropriately.)

Ground fault circuit interrupter (GFCI)—A device intended to protect people from electric shock. It de-energizes a

circuit or portion of a circuit within an established very brief period of time when a current to ground exceeds some

predetermined value (less than that required to operate the over-current protected device of the supply circuit).

Hot wires—Those that carry the electric current or power to the load; they are usually black or red.

Insulator—A material that will not permit the passage of electricity.

Kilowatt-hour (KWH)—The amount of energy supplied by one kilowatt (1,000 watts) for 1 hour (3,600 seconds), equal

to 3,600,000 joule. Electric bills are usually figured by the number of KWHs consumed.

Neutral wire—The third wire in a three-wire distribution circuit; it is usually white or light gray and is connected to the

ground.

Resistance—A measure of the difficulty of electric current to pass through a given material; its unit is the ohm.

Service—The conductor and equipment for delivering energy from the electricity supply system to the wiring system of

the premises.

Service drop—The overhead service connectors from the last pole or other aerial support to and including the splices, if

any, connecting to the service entrance conductors at the building or other structure.

Service panel—Main panel or cabinet through which electricity is brought to the building and distributed. It contains the

main disconnect switch and fuses or circuit breakers.

Short circuit—A break in the flow of electricity through a circuit due to the load caused by improper connection between

hot and neutral wires. 

Volt—The unit for measuring electrical pressure of force, which is known as electromotive force. Its symbol is “E.”

Voltage drop—A voltage loss when wires carry current. The longer the cord, the greater the voltage drop.

Watt—The unit of electric power. Volts times amperes = watts.

Definitions of Terms Related to Electricity
hot wires (black or red) are at a higher potential than are

the neutral or ground wire (white or green). 

Voltage is a measure of the force at which electricity is

delivered. It is similar to pressure in a water supply system.

Current is measured in amperes and is the quantity of

flow of electricity. It is similar to measuring water in

gallons per second. A watt is equal to volts times amperes.

It is a measure of how much power is flowing. Electricity

is sold in quantities of kilowatt-hours.

The earth, by virtue of moisture contained within the

soil, serves as a very effective conductor. Therefore, in

power transmission, instead of having both the hot and

neutral wires carried by the transmission poles, one lead

of the generator is connected to the ground, which serves

as a conductor (Figure 11.1). All electrical utility wires are

carried by the transmission towers and are considered hot

or charged. At the house, or point where the electricity is

to be used, the circuit is completed by another

connection to ground.

The electric power utility provides a ground somewhere

in its local distribution system; therefore, there is a

ground wire in addition to the hot wires within the

service drop. In Figure 11.1 this ground can be seen at

the power pole that contains the step-down transformer.

In addition to the ground connection provided by the

electric utility, every building is required to have an

independent ground called a system ground. The system

ground is a connection to ground from one of the

current-carrying conductors of the electrical system.

System grounding, applied to limit overvoltages in the

event of a fault, provides personnel safety, provides a

positive means of detecting and isolating ground faults,

and improves service reliability. Therefore, the system

ground’s main purpose is to protect the electrical system

itself and offers limited protection to the user.

The system ground serves the same purpose as the power

company’s ground; however, it has a lower resistance

because it is closer to the building. The equipment

ground protects people from potential harm during the

use of certain electrical equipment. The system ground

should be a continuous wire of low resistance and of

sufficient size to conduct current safely from lightning

and overloads.

Electric Service Entrance

Service Drop

To prevent accidental contact by people, the entrance

head (Figure 11.2) should be attached to the building at

least 10 feet above ground. The conductor should clear all

roofs by at least 8 feet and residential driveways by 12 feet.

For public streets, alleys, roads, and driveways on other than

residential property, the clearance must be 18 feet.

The wires or conductor should be of sufficient size to carry

the load and not smaller than No. 8 copper wire or equivalent.

For connecting wire from the entrance head to the service

drop wires, the code requires that the service entrance

conductors be installed either below the level of the

service head or below the termination of the service

entrance cable sheath. Drip loops must be formed on

individual conductors. This will prevent water from

entering the electric service system. The wires that form

the entrance cable should extend 36 inches from the

entrance head to provide a sufficient length to connect

service drop wires to the building with insulators. The

entrance cable may be a special type of armored outdoor

cable, or it may be enclosed in a conduit. The electric

power meter may be located either inside or outside the

Healthy Housing Reference Manual 11-3

Figure 11.1. Utility Overview [2] Figure 11.2. Entrance Head 
building. In either instance, the meter must be located

before the main power disconnect.

Figure 11.3 shows an armored cable service entrance with

a fuse system. Newer construction will have circuit

breakers, as shown in Figure 11.4. The armored cable is

anchored to the building with metal straps spaced every

4 feet. The cable is run down the wall and through a hole

drilled through the building. The cable is then connected to

the service panel, which should be located within 1 foot of

where the cable enters the building. The ground wire

need not be insulated. This ground wire may be either

solid or stranded copper, or a material with an equivalent

resistance. 

Figure 11.5 shows the use of thin-wall conduit in a service

entrance.

Underground Service

When wires are run underground, they must be protected

from moisture and physical damage. The opening in the

building foundation where the underground service enters

the building must be moisture proof. Refer to local codes

for information about allowable materials for this type of

service entrance.

Electric Meter

The electric meter (Figure 11.6) may be located inside or

outside the building. The meter itself is weatherproof and

is plugged into a weatherproof socket. The electric power

company furnishes the meter; the socket may or may not

be furnished by the power company.

Grounding

The system ground consists of grounding the neutral

incoming wire and the neutral wire of the branch circuits.

The equipment ground consists of grounding the metal

parts of the service entrance, such as the service switch, as

well as the service entrance conduit, armor or cable. 

Figure 11.5. Thin-wall Conduit [2]

Figure 11.3. Armored Cable Service Entrance [2]

Figure 11.4. Breakers [2]

11-4 Electricity
Poor grounding at any point can result in a person

providing a more effective route to ground than the

intended ground, resulting in electrocution. This can

occur from damaged insulation allowing electricity to

flow into the case or cabinet of the appliance.

The system must be grounded by two 8 foot by 5/8-inch

copper ground rods of at least 8 feet in length driven into

the ground and connected by a continuous (unbroken)

piece of copper wire (the size of this wire corresponds to

the size of the system main). It is highly recommended

that the system also be grounded to the incoming water line

or nearest cold water supply line if it is metal. 

The usual ground connection is to a conductive water

pipe of the city water system. The connection should be

made to the street side of the water meter, as shown in

Figure 11.7. If the water meter is located near the street

curb, then the ground connection should be made to the

cold water pipe as close as possible to where it enters the

building. It is not unusual for a water meter to be

removed from the building for service. If the ground

connection is made at a point in the water piping system

on the building side of the water meter, the ground

circuit will be broken on removal of the meter. This

broken ground circuit is a shock hazard if both sides of

the water meter connections are touched simultaneously.

Local or state codes should be checked to determine

compliance with correct grounding protocols.

In increasing instances, the connections between the

water meters and pipes are electrically very poor. In this

case, if the ground connection is made on the building

side of the water meter, there may not be an effective

ground. To prevent the two aforementioned situations,

the code requires effective bonding by a properly sized

jumper-wire around any equipment that is likely to be

disconnected for repairs or replacement.

Often, the house ground will be disconnected. Therefore,

the housing inspector should always check the house

ground to see if it is properly connected.

Figure 11.8 shows a typical grounding scheme at the

service box of a residence. In this figure, only the

grounded neutral wires are shown. The neutral strap is a

conductive bare metal strip that is riveted directly to the

service box. This conductive strip forms a collective

ground that joins the ground wires from the service

entrance, branch circuits, and house ground. 

Follow these key grounding points:

• Use two metal rods driven 8 feet into the ground. 

• Bond around water heaters and filters to assure

grounding.

• If water pipes are used, they must be supplemented with a second ground.

• Ground rod must be driven to full depth.

• If ground rod resistance exceeds 25 ohms, install

two rods at a minimum of 6 feet apart.

• When properly grounded, the metal frame of a

building can be used as a ground point.

• Do not use underground gas lines as a ground.

• Provide external grounds to other systems such as

satellite, telephone, and other services to further

protect the electrical system from surges.

Healthy Housing Reference Manual 11-5

Figure 11.6. Electric Meter

Figure 11.7. Typical Service Entrance [2]
• If the water service pipes to the home are not

metal or if all of the service components in the

home are not metal, then the water system cannot

play a role in grounding.

Bonding is necessary to provide a route for electricity to

flow around isolated elements of a piping system to

ensure electrical potential is minimized for both the

protection of the system from corrosion and to protect

individuals from electrical shock. 

Two- or Three-wire Electric Services

One of the wires in every electrical service installation is

supposed to be grounded. This neutral wire should always

be white. The hot wires are usually black, red, or some

other color, but never white.

The potential difference or voltage between the hot wires

and the ground or neutral wire of a normal residential

electrical system is 115 volts. Thus, where there is a twowire installation (one hot and one neutral), only 115 volts

are available.

When three wires are installed (two hot and one neutral),

either 115 or 230 volts are available. In a three-wire

system, the voltage between the neutral and either of the

hot wires is 115 volts; between the two hot wires, it is

230 (Figure 11.9). The major advantage of a three-wire

system is that it permits the operation of heavy electrical

equipment such as clothes dryers, cooking ranges, and air

conditioners, the majority of which require 230-volt

circuits. In addition, the three-wire system is split at the

service panel into two 115-volt systems to supply power

for small appliances and electric lights. The result is a

doubling of the number of circuits, and, possibly, a

corresponding increase in the number of branch circuits,

with a reduction in the probability of fire caused by

overloading electrical circuits if the electrical demands

exceed the capacity.

Residential Wiring Adequacy

The use of electricity in the home has risen sharply since

the 1930s. Many homeowners have failed to repair or

improve their wiring to keep it safe and up to date. In the

1970s, the code recommended that the main distribution

panel in a home be a minimum of 100 amps. Because the

number of appliances that use electricity has continued to

grow, so has the size of recommended panels. For a

normal house (2,500 to 3,500 square feet), a 200-amp

panel is recommended. The panel must be of the breaker

type with a main breaker for the entire system (Figure 11.4).

Fuse boxes are not recommended for new housing.

This type of service is sufficient in a one-family house or

dwelling unit to provide safe and adequate electricity for

the lighting, refrigerator, iron, and an 8,000-watt cooking

range, plus other appliances requiring a total of up to

10,000 watts.

Some older homes have a 60-ampere, three-wire service

(Figure 11.10). It is recommended that these homes be

rewired for at least the minimum of 200-amperes

recommended in the code. The 60-amp service is safely

capable of supplying current for only lighting and

portable appliances, such as a cooking range and regular

dryer (4,500 watts), or an electric hot water heater

(2,500 watts), and cannot handle additional major

appliances. Other older homes today have only a 30-ampere,

115-volt, two-wire service (Figure 11.11). This system can

safely handle only a limited amount of lighting, a few

minor appliances, and no major appliances. Therefore,

this size service is substandard in terms of the modern

household’s needs for electricity. Furthermore, it is a fire

hazard and a threat to the safety of the home and the

occupants. 

11-6 Electricity

Figure 11.9. Grounding [2]

Figure 11.8. Grounding Scheme [2]
Wire Sizes and Types

Aluminum wiring, used in some homes from the mid

1960s to the early 1970s, is a potential fire hazard [3].

According to the U.S. Consumer Product Safety

Commission (CPSC), fires and even deaths have been

caused by this hazard. Problems due to expansion can

cause overheating at connections between the wire and

devices (switches and outlets) or at splices. CPSC research

shows that homes wired with aluminum wire

manufactured before 1972 are 55 times more likely to

have one or more connections reach fire hazard

conditions than are homes wired with copper. Post-1972 

aluminum wire is also a concern. Introduction of

aluminum wire alloys around 1972 did not solve most of

the connection failure problems. Aluminum wiring is still

permitted and used for certain applications, including

residential service entrance wiring and single-purpose

higher amperage circuits such as 240-volt air conditioning

or electric range circuits. 

Reducing Risk

Only two remedies for aluminum wiring have been

recommended by the CPSC: discontinued use of the

aluminum circuit or the less costly option of adding

copper connecting “pigtail” wires between the aluminum

wire and the wired device (receptacle, switch, or other

device). The pigtail connection must be made using only

a special connector and special crimping tool licensed by

the AMP Corporation. Emergency temporary repairs

necessary to keep an essential circuit in service might be

possible following other procedures described by the

CPSC, and in accordance with local electrical codes [4,5].

Wire Sizes

Electric power actually flows along the surface of the wire.

It flows with relative ease (little resistance) in some materials,

such as copper and aluminum, and with a substantial

amount of resistance in iron. If iron wire were used, it

would have to be 10 times as large as copper wire to be as

effective in conducting electricity. In fine electronics, gold

is the preferred conductor because of the resistance to

corrosion and the very high conductivity.

Electricity is the movement of electrons from an area of

higher potential to one of lower potential. An analogy to

how electricity flows would be the flow of water along the

path of least resistance or down a hill. All it takes to

create the potential for electricity is the collection of

Healthy Housing Reference Manual 11-7

Figure 11.10. Three-wire Service [2] Figure 11.11. Two-wire Service [2]
electrons and a pathway for them to flow to an area of

lesser concentration along a conductor. When a person

walks across a nylon carpet in times of low atmospheric

humidity, his or her body will often collect electrons and

serve as a capacitor (a storage container for electrons).

When that person nears a grounding source, the electrons

will often jump from a finger to the ground, creating a

spark and small shock. 

A number preceded by the letters AWG (American Wire

Gauge) indicates copper wire sizes [6]. As the AWG

number of the wire becomes smaller, the size and current

capacity of the wire increases. AWG 14 is most

commonly found in older residential branch circuits.

AWG 14 wires should be used only in a branch circuit

with a 15-ampere capacity or no more than a 1,500-watt

demand. Wire sizes AWG 16, 18, and 20 are progressively

smaller than AWG 14 and are used for extension wires or

low-voltage systems. Wire of the correct size must be used

for two reasons: current capacity and voltage drop or loss. 

When current flows through a wire, it creates heat. The

greater the amount of flow, the greater the amount of

heat generated. (Doubling the amperes without changing

the wire size increases the amount of heat by four times.)

The heat is electric energy (electrons) that has been

converted into heat energy by the resistance of the wire.

The heat created by the coils in a toaster is an example of

designed resistance to create heat. Most heat developed by

an electrical conductor is wasted; therefore, the electric

energy used to generate it is also wasted. 

If the amount of heat generated by the flow of current

through a wire becomes excessive, a fire may result.

Therefore, the code sets the maximum permissible current

that may flow through a certain type and size wire. The 

blue box provides examples of current capacities for

copper wire of various sizes.

In addition to heat generation, there will be a reduction in

voltage as a result of attempting to force more current

through a wire than it is designed to carry. Certain

appliances, such as induction-type electric motors, may be

damaged if operated at too low a voltage.

Wire Types

All wires must be marked to indicate the maximum

working voltage, the proper type letter or letters for the

type wire specified in the code, the manufacturer’s name

or trademark, and the AWG size or circular-mil area

(Figure 11.12). A variety of wire types can be used for a

wide range of temperature and moisture conditions. The

code should be consulted to determine the proper wire

for specific conditions.

Types of Cable

Nonmetallic sheathed cable consists of wires wrapped in

plastic and then a paper layer, followed by another spiral

layer of paper, and enclosed in a fabric braid, which is

treated with moisture- and fire-resistant compounds.

Figure 11.12 shows this type of cable, which often is

marketed under the name Romex. This type of cable can

be used only indoors and in permanently dry locations.

Romex-type wiring is normally used in residential

construction. However, when cost permits, it is

recommended that a conduit-based system be used.

Armored cable is commonly known as BX or Flexsteel

trade names. Wires are wrapped in a tough paper and

covered with a strong spiral flexible steel armor. This type

of cable is shown in Figure 11.13 and may be used only

in permanently dry indoor locations. Armored cable must

be supported by a strap or staple every 6 feet and within

24 inches of every switch or junction box, except for

concealed runs in old work where it is impossible to

mount straps.

Cables are also available with other outer coatings of metals,

such as copper, bronze, and aluminum for use in a variety of

conditions. 

11-8 Electricity

Figure 11.12. Wire Markings [2]

Size wire (AWG) (larger wire, smaller number) #14 #12 #10 #8

Maximum capacity in amperes 15 20 30 40

Maximum Current Recommended for AWG Wire Size
Flexible Cords

CPSC estimates that about 4,000 injuries associated with

electric extension cords are treated in hospital emergency

rooms each year. About half of the injuries involve

fractures, lacerations, contusions, or sprains from people

tripping over extension cords. Thirteen percent of the

injuries involve children younger than 5 years of age;

electrical burns to the mouth account for half the injuries

to young children [7]. 

CPSC also estimates that about 3,300 residential fires

originate in extension cords each year, killing 50 people

and injuring about 270 others [7]. The most frequent

causes of such fires are short circuits, overloading the

system, and damage to or misuse of extension cords.

The Problem

Following are CPSC investigations of injuries that

illustrate the major injury patterns associated with

extension cords: children putting extension cords in their

mouths, overloaded cords, worn or damaged cords, and

tripping over cords: 

• A 15-month-old girl put an extension cord in her

mouth and suffered an electrical burn. She

required surgery.

• Two young children were injured in a fire caused

by an overloaded extension cord in their family’s

home. A lamp, TV set, and electric heater had

been plugged into a single, light-duty extension

cord.

• A 65-year-old woman was treated for a fractured

ankle after tripping over an extension cord.

The Standards

The code says that many cord-connected appliances

should be equipped with polarized grounding plugs.

Polarized plugs can only be inserted one way into the

outlet because one blade is slightly wider than the other.

Polarization and grounding ensure that certain parts of

appliances that could have a higher risk of electric shock

when they become live are instead connected to the

neutral, or grounded, side of the circuit. Such electrical

products should only be used with polarized or grounded

extension cords. 

Voluntary industry safety standards, including those of

Underwriter’s Laboratory (UL), now require that generaluse extension cords have safety closures, warning labels,

rating information about the electrical current, and other

features for the protection of children and other

consumers.

In addition, UL-listed extension cords now must be

constructed with 16-gauge or larger wire or be equipped

with integral fuses. The 16-gauge wire is rated to carry

13 amperes (up to 1,560 watts), as compared with the

formerly used 18-gauge cords that were rated for

10 amperes (up to 1,200 watts). 

Safety Suggestions

The following are CPSC recommendations [7] for

purchasing and safely using extension cords: 

• Use extension cords only when necessary and only

on a temporary basis.

• Use polarized extension cords with polarize

appliances.

• Make sure cords do not dangle from the counter

or tabletops where they can be pulled down or

tripped over.

• Replace cracked or worn extension cords with

new 16-gauge cords that have the listing of a

nationally recognized testing laboratory, safety

closures, and other safety features.

• With cords lacking safety closures, cover any

unused outlets with electrical tape or with plastic

caps to prevent the chance of a child making

contact with the live circuit.

• Insert plugs fully so that no part of the prongs is

exposed when an extension cord is in use.

• When disconnecting cords, pull the plug rather

than the cord itself.

• Teach children not to play with plugs and outlets.

• Use only three-wire extension cords for appliances

with three-prong plugs. Never remove the third

(round or U-shaped) prong, which is a safety

feature designed to reduce the risk for shock and

electrocution.

Healthy Housing Reference Manual 11-9

Figure 11.13. Armored Cable [2]
• In locations where furniture or beds may be

pushed against an extension cord where the cord

joins the plug, use a special angle extension cord

specifically designed for use in these instances.

• Check the plug and the body of the extension

cord while the cord is in use. Noticeable warming

of these plastic parts is expected when cords are

being used at their maximum rating. If the cord

feels hot or if there is a softening of the plastic,

this is a warning that the plug wires or

connections are failing and that the extension

cord should be discarded and replaced.

• Never use an extension cord while it is coiled or

looped. Never cover any part of an extension cord

with newspapers, clothing, rugs, or any objects

while the cord is in use. Never place an extension

cord where it is likely to be damaged by heavy

furniture or foot traffic.

• Do not use staples or nails to attach extension

cords to a baseboard or to another surface. This

could damage the cord and present a shock or fire

hazard.

• Do not overload extension cords by plugging in

appliances that draw a total of more watts than

the rating of the cord.

• Use special heavy-duty extension cords for highwattage appliances such as air conditioners,

portable electric heaters, and freezers.

• When using outdoor tools and appliances, use

only extension cords labeled for outdoor use.

Wiring

Open Wiring

Open wiring is a wiring method using knobs, nonmetallic

tubes, cleats, and flexible tubing for the protection and

support of insulated conductors in or on buildings and

not concealed by the structure. The term “open wiring”

does not mean exposed, bare wiring. In dry locations,

when not exposed to severe physical damage, conductors

may be separately encased in flexible tubing. Tubing

should be in continuous lengths not exceeding 15 feet

and secured to the surface by straps not more than

41⁄2 feet apart. Tubing should be separated from other

conductors by at least 21⁄2 inches and should have a

permanently maintained airspace between them and any

and all pipes they cross. 

Concealed Knob and Tube Wiring

Concealed knob and tube wiring is a wiring method

using knobs, tubes, and flexible nonmetallic tubing for

the protection and support of insulated wires concealed in

hollow spaces of walls and ceilings of buildings. This

wiring method is similar to open wiring and, like open

wiring, is usually found only in older buildings.

Electric Service Panel

The service switch is a main switch that will disconnect

the entire electrical system at one time. The main fuses or

circuit breakers are usually located within the service

switch box. The branch circuit fuse or circuit breaker may

also be located within this box.

According to the code, the switch must be externally

operable. This condition is fulfilled if the switch can be

operated without the operator being exposed to

electrically active parts. Figure 11.14 shows a 200-amp

service box. Figure 11.15 shows an external “hinged

switch” power shutoff installed on the outside of a home. 

Most of today’s older homes do not have hinged switches.

Instead, the main fuse is mounted on a small insulated

block that can be pulled out of the switch. When this

block is removed, the circuit is broken.

In some installations, the service switch is a “solid

neutral” switch, meaning that the switch or a fuse does

not break the neutral wire in the switch.

When circuit breakers are used in homes instead of fuses,

main circuit breakers may or may not be required. If it

takes more than six movements of the hand to open all

the branch-circuit breakers, a main breaker, switch, or

fuse will be required ahead of the branch-circuit breakers.

Thus, a house with seven or more branch circuits requires

a separate disconnect means or a main circuit breaker

ahead of the branch-circuit breakers. 

Over-current Devices

The amperage (current flow) in any wire is limited to the

maximum permitted by using an over-current device of a

size specified by the code. Four types of over-current

devices are common: circuit breakers, ground fault circuit

interrupters (GFCIs), arc fault circuit interrupters

(AFCIs), and fuses. The over-current device of a specific

size is specified by the code. The over-current device must

be rated at equal or lower capacity than the wire of the

circuit it protects. 

11-10 Electricity
Circuit Breakers (Fuseless Service Panels)

A circuit breaker looks something like an ordinary electric

light switch. Figure 11.14 shows the service box in a 200-

amp fuseless system. Figure 11.15 shows a service switch.

There is a handle that may be used to turn power on or

off. Inside is a simple mechanism that, in case of a circuit

overload, trips the switch and breaks the circuit. The

circuit breaker may be reset by turning the switch to off

and then simply resetting the switch to the on position. A

circuit breaker is capable of taking harmless short-period

overloads (such as the heavy initial current required in the

starting of a washing machine or air conditioner) without

tripping, but protects against prolonged overloads. After

the cause of trouble has been located and corrected, power

is easily restored. Fuseless service panels or breaker boxes are

usually broken up into the following circuits:

• A 100-ampere or larger main circuit breaker that

shuts off all power.

• A 40-ampere circuit for an appliance such as an

electric cooking range.

• A 30-ampere circuit for a clothes dryer, water

heater, heat pump, or central air conditioning.

• A 20-ampere circuit for small appliances and

power tools.

• A 15-ampere circuit for general-purpose lighting,

TVs, VCRs, computers, and vacuum cleaners.

• Space for new circuits to be added if needed for

future use.

Ground Fault Circuit Interrupters 

Unlike circuit breakers and fuses, GFCIs are installed to

protect the user from electrocution. These devices provide

protection against electrical shock and electrocution from

ground faults or contact with live parts by a grounded

individual. They constantly monitor electrical currents

flowing into a product. If the electricity flowing through

the product differs even slightly from that returning, the

GFCI will quickly shut off the current. GFCIs detect

amounts of electricity much smaller than those required

for a fuse or circuit breaker to activate and shut off the

circuit. UL lists three types of GFCIs designed for home

use that are readily available and fairly inexpensive and

simple to install: 

• Wall Receptacle GFCI—This type of GFCI

(Figure 11.16) is used in place of a standard

receptacle found throughout the house. It fits into

a standard outlet box and protects against ground

faults whenever an electrical product is plugged

into the outlet. If strategically located, it will also

provide protection to downstream receptacles. 

• Circuit Breaker GFCI—In homes equipped with

circuit breakers, this type of GFCI may be

installed in a panel box to protect selected circuits.

A circuit breaker GFCI serves a dual purpose: it

shuts off electricity in the event of a ground fault

Figure 11.14. 200-Amp Service Box Figure 11.15. External Power Shutoff and Meter 

Healthy Housing Reference Manual 11-11
and will also trip when a short circuit or an

overload occurs.

• Portable GFCI—A portable GFCI requires no

special knowledge or equipment to install. One

type contains the GFCI circuitry in a selfcontained enclosure with plug blades in the back

and receptacle slots in the front. It can be plugged

into a receptacle, and the electrical product

plugged into the GFCI. Another type of portable

GFCI is an extension cord combined with a

GFCI. It adds flexibility in using receptacles that

are not protected by GFCIs. 

Once a GFCI is installed, it must be checked monthly to

determine that it is operating properly. Pressing the test

button can check units; the GFCI should disconnect the

power to that outlet. Pressing the reset button reconnects

the power. If the GFCI does not disconnect the power,

have it checked by a qualified, certified electrician. 

GFCIs should be installed on circuits in the following

areas: garages, bathrooms, kitchens, crawl spaces,

unfinished basements, hot tubs and spas, pool electronics,

and exterior outlets. However, they are not required on

single outlets that serve major appliances.

Arc-fault Circuit Interrupters 

Arc-fault circuit interrupters are new devices intended to

provide fire protection by opening the circuit if an arcing

fault is detected. An arcing fault is an electric spark or hot

plasma field that extends from the hot wire to a ground.

An arc is a luminous discharge of electricity across an

insulating medium or simply a spark across an air gap.

Arcs occur every day in homes. For example, an arc

occurs inside the switch when a light is turned on. Toy

racecars and trains create arcs. The motors inside hair

dyers and power drills have tiny arcs. All of these are

controlled arcs. It is the

uncontrolled or nondesigned

arc that is a serious fire hazard

in the home. The arc-fault

circuit interrupter looks like

the GFCI unit (Figure 11.17),

but it is not designed to

protect against electric shock.

Because most electrical wiring

in a home is hidden from

view, many arc faults go

undetected and continue

arcing indefinitely. If left in

this arcing state, the potential

for fire increases. It is estimated that about one third of

fires are caused by arcing faults. Normal fuses and circuit

breakers are not capable of detecting arc faults and therefore

will not open the circuit and stop the flow of electricity.

Fused Ampere Service Panel (Fuse Box)

Fuse-type panel boxes are generally found in older homes.

They are as safe and adequate as a circuit breaker of

equivalent capacity, provided fuses of the proper size are used. 

A fuse, like a circuit breaker, is designed to protect a

circuit against overloading and short circuits and does so

in two ways.

When a fuse is blown by a short circuit, the metal strip is

instantly heated to an extremely high temperature, and

this heat causes it to vaporize. A fuse blown by a short

circuit may be easily recognized because the window of

the fuse usually becomes discolored.

In a fuse blown by an overload, the metal strip is melted

at its weakest point, breaking the flow of current to the

load. In this case, the window of the fuse remains clear;

therefore, a blown fuse caused by an overload may also be

easily recognized.

Sometimes, although a fuse has not been blown, the

bottom of the fuse may be severely discolored and pitted.

This indicates a loose connection because the fuse was not

screwed in properly.

It is critical to check that all fuses are properly rated for

the designed amperage. The placing of a fuse with a

higher amperage than recommended presents a significant

fire hazard. 

Generally, all fused panel boxes are wired similarly for

two- and three-wire systems. In a two-wire-circuit panel

box, the black or red hot wire is connected to a terminal

of the main disconnect, and the white or light gray

neutral wire is connected to the neutral strip, which is then

grounded to the pipe on the street side of the water meter.

In a three-wire system, the

black and red hot wires are

connected to separate

terminals of the main

disconnect, and the neutral

wire is grounded the same as

for a two-wire system. Below

each fuse is a terminal to

which a black or red wire is

11-12 Electricity

Figure 11.16. GFCI 

Figure 11.17. Arc Interrupter 
connected. The white or light gray neutral wires are then

connected to the neutral strip. Each fuse indicates a

separate circuit (Figure 11.18).

• Nontamperable fuses—All ordinary plug fuses

have the same diameter and physical appearance,

regardless of their current capacity, whereas

nontamperable fuses are sized by amperage load.

Thus, with regular fuses, if a circuit designed for a

15-ampere fuse is overloaded so that the 15-ampere

fuse blows out, nothing will prevent a person

from replacing the 15-ampere fuse with a 20- or

30-ampere fuse, which may not blow out. If a

circuit wired with 14-gauge wire (current capacity

15 amperes) is fused with a 20- or 30-ampere fuse

and an overload develops, more current than the

14-gauge wire is safely capable of carrying could

pass through the circuit. The result would be a

heating of the wire and potential fire.

• Type-S fuses—Type-S fuses have different lengths

and diameter threads for each amperage capacity.

An adapter is first inserted into the ordinary fuse

holder, which adapts the fuse holder for only one

capacity fuse. Once the adapter is inserted, it

cannot be removed.

• Cartridge fuses—A cartridge fuse protects an

electric circuit in the same manner as an ordinary

plug fuse, already described, protects an electric

circuit. Cartridge fuses are often used as main fuses.

Electric Circuits

An electric circuit in good repair carries electricity

through two or three wires from the source of supply to

an outlet and back to the source. A branch circuit is an

electric circuit that supplies current to a limited number

of outlets and fixtures. A residence generally has many

branch circuits. Each is protected against short circuits

and overloads by a 15- or 20-ampere fuse or circuit breaker.

The number of outlets per branch circuit varies from

building to building. The code requires enough light

circuits so that 3 watts of power will be available for each

square foot of floor area in a house. A circuit wired with

14-gauge wire and protected by a 15 ampere over-current

protection device provides 15×115 (1,725 watts); each

circuit is enough for 1,725 divided by 3 (575 square feet).

Note that 575 is a minimum figure; if future use is

considered, 500 or even 400 square feet per branch circuit

should be used.

Special appliance circuits will provide electric power for

lighting, radio, TV, and small portable appliances.

However, the larger electric appliances usually found in

the kitchen consume more power and must have their

own special circuit.

Section 220-3b of the code requires two special circuits to

serve only appliance outlets in the kitchen, laundry,

pantry, family room, dining room, and breakfast room.

Both circuits must be extended to the kitchen; either one

or both of these circuits may serve the other rooms. No

lighting outlets may be connected to these circuits, and

they must be wired with 12-gauge wire and protected by

a 20-ampere over-current device. Each circuit will have a

capacity of 20×115 (2,300 watts), which is not too much

when toasters often require more than 1,600 watts.

It is customary to provide a circuit for each of the

following appliances: range, water heater, washing

machine, clothes dryer, garbage disposal, dishwasher,

furnace, water pump, air conditioner, heat pump, and air

compressor. These circuits may be either 115 volts or

230 volts, depending on the particular appliance or motor

installed.

Outlet Switches and Junction Boxes

The code requires that every switch, outlet, and joint in

wire or cable be housed in a box. Every fixture must be

mounted on a box. Most boxes are made of plastic or

metal with a galvanized coating. When a cable of any

style is used for wiring, the code requires that it be

securely anchored with a connector to each box it enters.

Grounding Outlets

An electrical appliance may appear to be in good repair,

and yet it might be a danger to the user. Older portable

Healthy Housing Reference Manual 11-13 Figure 11.18. Types of Fuses 
electric drills consist of an electric motor inside a metal

casing. When the switch is depressed, the current flows to

the motor and the drill rotates. As a result of wear,

however, the insulation on the wire inside the drill may

deteriorate and allow the hot side of the power cord to

come in contact with the metal casing. This will not

affect the operation of the drill.

A person fully clothed using the drill in the living room,

which has a dry floor, will not receive a shock, even

though he or she is in contact with the electrified drill

case. The operator’s body is not grounded because of the

dry floor. If standing on a wet basement floor, the

operator’s body might be grounded; and, when the

electrified drill case is touched, current will pass through

the operator’s body.

To protect people from electrocution, the drill case is

usually connected to the system ground by means of a

wire called an appliance ground. In this instance, as the

drill is plugged in, current will flow between the shorted

hot wire and the drill case and cause the over-current

device to break the circuit. Thus, the appliance ground

has protected the human operator. Newer appliances and

tools are equipped with two-prong polarized plugs, as

discussed in the standards section of this manual.

The appliance ground (Figure 11.19) is the third wire

found on many appliances. The appliance ground will be

of no use unless the outlet into which the appliance is

plugged is grounded. Being in physical contact with a

ground outlet box grounds the outlet. Having a third

ground wire, or a grounded conduit, as part of the circuit

wiring grounds the outlet box. 

All new buildings are required to have grounded outlets.

A two-lead circuit tester can be used to test the outlet.

The circuit tester lights when both of its leads are plugged

into the two elongated parallel openings of the outlet. In

addition, the tester lights when one lead is plugged into

the round third opening and the other is plugged into the

hot side of the outlet. Most problems can be resolved

using inexpensive testers resembling a plug with three

leads. These can be purchased in many stores and most

hardware stores for very reasonable prices. 

If the conventional two-opening outlet is used, it may be

grounded if the screw that holds the outlet cover plate is

electrically connected to the third-wire ground. The tester

should light when one lead is in contact with a clean

paint-free metal outlet cover plate screw and the hot side

of the outlet. If the tester does not light, the outlet is not

grounded. If a two-opening outlet is grounded, it may be

adapted for use by a three-wire appliance by using an

adapter. The loose-wire portion or screw tab of the

adapter should be secured behind the metal screw of the

outlet plate cover. Many appliances, such as electric

shavers and some new hand tools, are double insulated

and are safe without having a third ground wire.

Polarized Plugs and Connectors

Plugs are polarized or unpolarized. Polarization helps

reduce the potential for shock. Consumers can easily

identify polarized plugs; one blade-the ground prong-is

wider than the other. Three-conductor plugs are

automatically polarized because they can only be inserted

one way. Polarized plugs are used to connect the mostexposed part of an appliance to the ground wire so that if

you are touching a ground (such as a pipe, bathtub, or

faucet) and the exposed part of an appliance (the case, the

threaded part of a light bulb socket, etc.), you will not get

an electrical shock. Many appliances, such as electric

drills, are doubly insulated so the probability of any

exposed part of the appliance being connected, by a short

or other problem in the appliance, to either wire is very

small. Such devices often use unpolarized plugs where the

two prongs of the plug are identical. 

Common Electrical Violations

The most obvious things that a housing inspector must

check are the power supply; the type, location, and

condition of the wiring; and the number and conditions of

wall outlets or ceiling fixtures required by the local code. In

making an investigation, the following considerations will

serve as useful guides.

11-14 Electricity

Figure 11.19. Appliance Ground and Grounded Plug 
• Power supply—Where is it, is it grounded

properly, and is it at least of the minimum

capacity required to supply current safely for

lighting and the major and minor appliances in

the dwelling?

• Panel box covers or doors—These should be

accessible only from the front and should be

sealed in such a way that they can be operated

safely without the danger of contact with live or

exposed parts of the wiring system.

• Switch, outlets, and junction boxes—These also

must be covered to protect against danger of

electric shock.

• Frayed or bare wires—These are usually the result

of long use and drying out and cracking of the

insulation, which leave the wires exposed, or of

constant friction and rough handling of the wire,

which cause it to fray or become bare. Wiring in

this condition constitutes a safety hazard. Correction

of such defects should be ordered immediately.

• Electric cords under rugs or other floor

coverings—Putting electric cords in locations

such as these is prohibited because of the potential

fire hazard caused by continuing contact over a

period of time between these heat-bearing cords

and the flammable floor coverings. Direct the

occupant to shift the cords to a safe location, explain

why, and make sure it is done before you leave.

• Ground fault circuit interrupter—All bathroom,

kitchen, and workroom outlets-where shock

hazard is great-should have GFCI outlets. Check

for lack of or nonuse of GFCI outlets. 

• Bathroom lighting—Bathrooms should include at

least one permanently installed ceiling or wall

light fixture with a wall switch and plate located

and maintained so that there is no danger of short

circuiting from use of other bathroom facilities or

splashing water. Fixture or cover plates should be

insulated or grounded.

• Lighting of public hallways, stairways, landings,

and foyers—A common standard is sufficient

lighting to illuminate 10 foot-candles on every part

of these areas at all times. Sufficient lighting

means that people can clearly see their feet on all

parts of the stairways and halls. Public halls and

stairways in structures containing less than three

dwelling units may be supplied with conveniently

located light switches controlling an adequate

lighting system that may be turned on when

needed, instead of full-time lighting.

• Habitable room lighting—The standard here

may be two floor convenience outlets (although

floor outlets are dangerous unless protected by

proper dust and water covers) or one convenience

outlet and one wall or ceiling electric light fixture.

This number is an absolute and often inadequate

minimum, given the contemporary widespread

use of electricity in the home. The minimum

should be the number required to provide

adequate lighting and power to accommodate

lighting and appliances normally used in each room.

• Octopus outlets or wiring—This term is applied

to outlets into which plugs have been inserted and

are being used to permit more than two lights or

portable appliances, such as a TV, lamp, or radio,

to be connected to the electrical system. The

condition occurs where the number of outlets is

insufficient to accommodate the normal use of

the room. This practice overloads the circuit and

is a potential source of fire.

• Outlet covers—Every outlet and receptacle must

be covered by a protective plate to prevent contact

of its wiring or terminals with the body,

combustible objects, or water.

Following are six situations that can cause danger and

should also be corrected.

Excessive or Faulty Fusing

The wire’s capacity must not be exceeded by the fuse or

circuit breaker capacity or be left unprotected by faulty

fusing or circuit breakers. Fuses and circuit breakers are

safety devices designed to “blow” to protect against

overloading the electrical system or one or more of its

circuits. Pennies under fuses are there to bypass the fuse.

These are illegal and must be removed. Overfusing is

done for the same reason. The latter can be prevented by

installing modern fusestats, which prevent use of any fuse of a

higher amperage than can be handled by the circuit it serves.

Cords Run Through Walls or Doorways and 

Hanging Cords or Wires

This makeshift installation often is the work of an

unqualified handyman or do-it-yourself occupant. The

Healthy Housing Reference Manual 11-15
inspector should check the local electrical code to

determine the policy regarding this type of installation.

Temporary Wiring

Temporary wiring should not be allowed, with the

exception of extension cords that go directly from

portable lights and electric fixtures to convenience outlets.

Excessively Long Extension Cords

City code standards often limit the length of loose cords

or extension lines to a maximum of 8 feet. This is

necessary because cords that are too long will overheat if

overloaded or if a short circuit develops and, thus, create a

fire hazard. This requirement does not apply to specially

designed extension cords for operating portable tools and

trouble lights.

Dead or Dummy Outlets

These are sometimes installed to deceive the housing

inspector. All outlets must be tested or the occupants

questioned to see if these are live and functioning

properly. A dead outlet cannot be counted to determine

compliance with the code.

Aluminum Wiring Inside the Home

Although aluminum is an excellent conductor, it tends to

oxidize on the conducting surface. The nonconductive

oxidized face of the conductor will arc from the remaining

conductive surfaces, and this arc can result in fire. 

Inspection Steps

The basic tools required by a housing inspector for

making an electrical inspection are fuse and circuit testers

and a flashlight. The first thing to remember is that you

are in a strange house, and the layout is unfamiliar to

you. The second thing to remember is that you are

dealing with electricity-take no chances. Go to the site of

the ground, usually at the water meter, and check the

ground. It should connect to the water line on the street

side of the water meter or be equipped with a jumper

wire. Do not touch any box or wire until you are sure of

the ground. Go to the main fuse box or circuit breaker

box and check all fuses and breakers for operational

integrity (proper amperage range; functional). Note the

condition of the wiring and of the box itself and check

whether it is over-fused. Examine all wiring in the

basement. Make sure you are standing in a dry spot

(concrete poses a particular problem because you cannot

determine its water content from visual examination)

before touching any electrical device. Standing on a dry

piece of wood is far safer than standing on concrete. Do 

not disassemble the fuse box, circuit breaker, or other

devices. Decisions must be made on what you see. If in

doubt, consult your supervisor. 

Note whether any fuse boxes, circuit breakers, or junction

boxes are uncovered. Examine all wiring for frayed or bare

spots; improper splicing; or rotted, worn, or inadequate

insulation. Avoid all careless touching; when in

doubt—DON’T! If you see bare wires, have the owner

call an electrician. Look for wires or cords in use in the

basement. Be certain all switch boxes and outlets are in a

tight, sound condition. Make sure that the emergency

switch for an oil burner is at the top of the basement

stairs, not on top of the unit.

Bathrooms, kitchens, and utility rooms-where electric

shock hazard is great-should have GFCI outlets. 

While inspecting the bathroom, also check for dangerous

items, such as radios that are not made for bathroom use

or portable electric heaters. Have inappropriate items

removed immediately. Such items have killed thousands

of people who touched them after getting out of the

bathtub or shower while still wet or because the appliance

fell into water the person had contact with. 

Electric washer and dryer combinations should have a

240-volt circuit, 30-ampere service connected to a

separate fuse or circuit breaker. Washer and dryer

combinations and other portable appliances should be

served by sufficiently heavy electrical service. If either of

these special lines is not available under the above-stated

conditions, consult your supervisor.

An electric range needs a 50-ampere, 240-volt circuit. A

dishwasher needs a 20-ampere, 120-volt circuit. A

separate three-wire circuit must be installed for an electric

water heater. Continue your inspection systematically

through the house.

To sum up, the housing inspector investigates specified

electrical elements in a house to detect any obvious

evidence of an insufficient power supply, to ensure the

availability of adequate and safe lighting and electrical

facilities, and to discover and correct any obvious hazard.

Because electricity is a technical, complicated field, the

housing inspector, when in doubt, should consult his or

her supervisor. The inspector cannot, however, close the

case until appropriate corrective action has been taken on

all such referrals.

11-16 Electricity
References

1. National Fire Protection Association. National

electrical code handbook 2005. Florence, KY:

Thomson Delmar Learning; 2005.

2. Center for Disease Control. Basic housing

inspection. Atlanta: US Department of Health

and Human Services; 1976.

3. British Columbia Safety Authority. The facts

about aluminum wiring in the home. New

Westminster, British Columbia, Canada: British

Columbia Safety Authority; no date. Available

from URL: http://www.safetyauthority.ca/

services/esp/

The_Facts_About_Aluminum_Wiring_In_The_

Home.pdf.

4. Consumer Product Safety Commission. May is

National Electrical Safety Month: good news for

homeowners-aluminum wiring fix still available.

Washington, DC: Consumer Product Safety

Commission; 2003. Available from URL:

http://www.cpsc.gov/CPSCPUB/PREREL/prhtml

03/03120.html.

5. Consumer Product Safety Commission. CPSC

safety recommendations for aluminum wiring in

homes. Washington, DC: Consumer Product

Safety Commission; 1974. Available from URL:

http://www.cpsc.gov/CPSCPUB/PREREL/prhtml

74/74040.html.

6. AWG American wire gauge/diameter/resistance.

Cologne, Germany: Bernd Noack; no date.

Available from URL:

http://www.bnoack.com/data/wireresistance.html.

7. Consumer Product Safety Commission. Extension

cords fact sheet. Washington, DC: Consumer

Product Safety Commission; no date. CPSC #16.

Available from URL:

http://www.cpsc.gov/CPSCPUB/PUBS/16.html. 

Additional Sources of Information

Croft T, Summers W. American electricians’ handbook.

14th edition, New York: McGraw-Hill Professional; 2002. 

Tuck D, Tuck G, Woodson RD. Electrician’s instant

answers. New York: McGraw-Hill Professional; 2003.

Black and Decker. The complete guide to home wiring: a

comprehensive manual, from basic repairs to advanced

projects (Black & Decker Home Improvement Library;

US edition). Chanhassen, MN: Creative Publishing

International; 2001.

Sunset Publishing. Basic wiring. 3rd edition. Menlo Park,

CA: Sunset Books, 1995.

Hometime.com. Electrical service panel: panel

components, circuit breakers, fuses, electrical glossary.

Hometime.com; no date. Available from URL:

http://www.hometime.com/Howto/ projects/

electric/elec_2.htm.

Vandervort D. How your house works: electric systems.

Glendale, CA: Hometips.com; no date. Available from

URL: http://www.hometips.com/hyhw/

electrical/electric.html.

PNM Resources. Residential subdivisions: electric service

requirements. In: Electric service guide. Albuquerque,

NM: PNM; 2004. Available from URL:

http://www.pnm.com/esg/chapters/56-63.pdf.

Textor K. Extension cord basics. Fine Homebuilding

2000, 129: 84-9. Available from URL:

http://www.taunton.com/finehomebuilding/

pages/h00010.asp.

Consumer Product Safety Commission. Repairing

aluminum wiring. Washington, DC: Consumer Product

Safety Commission; 1994. CPSC #516. Available from

URL: http://www.cpsc.gov/CPSCPUB/PUBS/516.pdf.

Healthy Housing Reference Manual 11-17
11-18 Electricity