American wire gauge (6AWG) copper. Ground
current leaks and shut off power
and should be replaced by an electrician.)
rods are typically
almost instantaneously. They are
1⁄2-in. or 5⁄8-in. copper-clad steel
If your home has a fuse panel instead, remove especially important in kitchens
rods at least 8 ft. long. The Ufer or concrete-
the fuse that controls the circuit, and tape a sign
and bathrooms, where water and
encased electrode is the preferred grounding
to the panel cover warning that the fuse should
dampness increase the potential
electrode, and must be used if new concrete foot-
not be reinstalled until work has been completed. for shocks.
ings are poured.
(You can also lock the panel cover.) Partially
unscrewing a fuse is not a solution because the
gfCis
fuse body is still in contact with the socket and
Ground-fault circuit interrupters (GFCIs) are
possibly could be jiggled or screwed in enough to
sensitive devices that can detect very small cur-
reenergize the circuit. Remove the fuse. Likewise,
rent leaks and shut off power almost instanta-
if circuits are controlled by cartridge fuses, pull
neously. The NEC now requires GFCI protection
the cartridge or cartridge block out of the panel.
on all bathroom receptacles, all receptacles serv-
In any case, once you’ve cut off the power,
ing kitchen counters, receptacles within 6 ft. of a
shut the panel cover and tape a sign to it, telling
sink other than in kitchens, all outdoor recepta-
others to stay out. Otherwise, someone not aware
cles, all unfinished basement receptacles, all
of the situation could flip the switch on, energiz-
garage receptacles, and all receptacles near pools, ing the circuit you’re working on.
PAnEl SAfETY
Once the power is off, post a warning
sign to prevent others from turning
the power back on while you’re still
In a breaker box, simply flip the relevant breaker to the
If you’re working on a fuse panel, unscrew and remove the working on a circuit. Even better, lock
off position.
fuse that protects the circuit you’re working on.
the panel.
electrical Wiring
267
USInG A vOlTAGE TESTEr
When using any type of voltage
When testing a receptacle, insert the tester in all slots and . . . remove the cover plate and unscrew the device from tester, always test the tester on an
touch it to the plate screw as well. If the tester does not
the box. Then, being careful not to touch the terminal
outlet that you know is hot—to be
light, the power is probably off. But to be doubly sure . . .
screws, wires, or box, apply the tester to all conductors. If
sure it is operating properly. Here, the
the tester still doesn’t light, it’s safe to work in the box.
glowing point of a noncontact
tester indicates voltage is present.
TesTing WiTh a
Planning an
non-ConTaCT TesTer
Electrical Remodel
A non-contact tester is a popular battery-operated Being detail oriented is as important to planning
voltage tester that is reliable, inexpensive, and
as it is to installation. When you plan a wiring
small enough to fit in a shirt pocket. Its plastic
project, be methodical: Assess the existing sys-
tip glows (and it may beep, depending on the
tem, calculate electrical loads, check local codes,
model) when it is brought close to or touched to a and draw a wiring floor plan.
hot (energized) screw terminal, receptacle slot,
If you are only replacing existing devices—
wire, or other item. Each time you use a non-
changing a light fixture, replacing a faulty switch,
contact tester—or any voltage tester—test that it’s or upgrading a receptacle, for example—you sel-
functioning properly first on a receptacle that
dom need a permit from the local building
you know is hot, and test it afterward as well.
department. However, if you extend or add any
After shutting off power at the panel, insert
circuit, you must get a permit.
the tester tip into the narrow (hot) slot of a recep-
Most local electrical codes are based on the
tacle. If the tester tip does not glow, there is prob-
NEC. When it’s necessary to pull a permit, local
ably no voltage present. To be sure, insert the tes-
code authorities will want to approve your plans
ter tip into the receptacle’s wide (neutral) slot and and later inspect the wiring to be sure it’s correct.
into the grounding slot. This should protect you
Don’t short-cut this process: Codes and inspec-
in case the receptacle was incorrectly wired.
tions protect you and your home.
If you need to remove the receptacle—say, to
Whatever the scope of your project, if you
replace it—remove the cover and test one more
work on existing circuits, first turn off the power,
time. Being careful not to touch the sides of the
test to be sure it’s off, and tag or lock the panel.
receptacle, unscrew the two mounting screws
holding the receptacle to the outlet box. (If the
insPeCTing The fuse
box is metal, avoid touching it, too.) Grasp the
box or breaker Panel
mounting straps, and gently pull the receptacle
out of the box. First, touch the tip of the tester to
By looking at the outside of the service panel and
the hot (black) wire and to the brass screw termi-
wiring that’s exposed in the basement and attic,
nal, then touch the tip to the white (neutral) wire you can get a basic overview of the system’s con-
and to the silver screw terminal. Also test the
dition. If the panel has unused breaker spaces
green (grounding) terminal and wire. If the tester and the wiring insulation is in decent shape, you
tip does not glow, it’s safe to handle the recepta-
can probably continue using it and safely add an
cle and the wires feeding it.
outlet or two. However, if the system seems
A non-contact tester will often glow when its
unsafe or inadequate, hire a licensed electrician
tip is merely near a hot wire—that is, it can
to open the panel and do a more thorough exami-
“read” current through a wire’s insulation or
nation.
through a cover plate. Thus you can sometimes
Here’s what to look for:
detect electrical current at a switch or fixture
Start your investigation at the fuse box or
without removing the outlet cover.
breaker panel. You can learn a lot about the con-
dition of the system by examining the outside
268 Chapter 11
of the service box. Examining the inside of a
Here, again, have an electrician examine the cir-
panel or fuse box is best left to a licensed electri-
cuits for damage to the wire insul
ation.
cian, however.
Panel covers that don’t fit, have gaps, or are
Rust and corrosion on the outside of a service missing are unsafe. So, if you see covers that
box or on the armored cable or conduit feeding it have been cut to fit a breaker, housing knockouts
can indicate corroded connections inside. Faulty
that are missing, bus bars that are visible when
connections can lead to arcing (sparks leaping
the panel cover is on, or mismatched compo-
gaps between wires) and house fires, so have a
nents, hire a licensed electrician to assess and
licensed electrician replace the fuse box or panel. correct those problems. Some older brands of
Likewise, if you see scorch marks on breakers or
panels and breakers, such as Federal Pacific®
a panel, have a pro examine it.
and Zinsco®, have a host of well-documented
Melted wire insulation is a sign either of an
failures and so should be carefully checked and,
overheated circuit—usually caused by too many
where necessary, replaced.
appliances in use at the same time—or of a poor
Missing cable connectors or unfilled knock-
wire connection in which arcing has occurred. In outs enable mice and vermin to enter the panel
the first case, a homeowner typically installs an
and nest in it, which can be a fire hazard.
oversize fuse or breaker to keep an overloaded
Missing connectors also allow cables to be
circuit from blowing so often, but this “remedy”
yanked, stressing electrical connections inside
exceeds the current-carrying capacity of the wire. the panel. A missing cable clamp may also allow
The wire overheats and melts the insulation, which the sharp edge of the panel to slice through ther-
can lead to arcing, house fires, or—if someone
moplastic cable sheathing, which could energize
Unsafe! All cables entering a panel
touches that bare copper wire—electrocution.
the panel (if the grounding of the system is not
must be protected by a cable clamp
An oversize fuse may not melt wires where
correct) and electrocute anyone who touches it.
inserted into a panel knockout. Sharp
you can see them, but it may have damaged wire
A properly grounded panel will have a large
panel edges could slice the insulation
of this unprotected cable. Also, for
insulation in a place you can’t see. Have an elec-
grounding wire running from the panel to a
the cables, the sheathing must extend
trician inspect the electrical system. Installing
grounding electrode (which could be a metal
at least ¼ in. into the box.
type-S fuse socket inserts can prevent overfusing.
underground water pipe, a ground rod driven
“Pennying” a fuse is another unsafe way to
into the earth, or a Ufer electrode). For the entire
deal with an overloaded circuit that keeps blow-
electrical system to be grounded, there must be a
ing fuses. In this case, someone unscrews a fuse,
continuous ground wire or other effective
inserts a penny or a blank metal slug into the bot- grounding path running from each device or fix-
tom of the socket—a dangerous act in itself—and ture to the service panel and, by extension, to the
then reinstalls the fuse. The penny allows current grounding electrode. Cold-water and gas pipes
to bypass the fuse and the protection it offers.
must also be connected (bonded) to the ground-
ing bus in the panel.
a 30-year Pro’s Take on rewiring
if the wiring in an older home appears to be sound and in good repair (see the warn-
ing signs below) it’s probably ok to continue using it, even though it may not meet
code requirements for a new installation. if you are planning to gut the house com-
pletely, it makes sense to rip out all the old wiring and completely rewire the house. if
you’re remodeling only part of the house, leave most of the old wiring in place if it is
sound and spend your money rewiring the kitchen, baths, and laundry circuits. That
will give you more bang for your buck.
however, you should replace old wiring that’s unsafe. if you observe any of these
conditions, the wiring should be replaced:
Circuits that have been extended improperly, as evidenced by loose connections,
unprotected splices, or arcing.
knob-and-tube wiring whose insulation has deteriorated or that has been dam-
aged. also, if knob-and-tube wiring in the attic has been covered with loose-fill insu-
lation or insulation batts, that is a serious code violation that could lead to overheat-
This 30amp main switch and fuses was the panel for
ing and fire danger.
the whole house. It has seen better days. Even if it were
Circuits wired with unsheathed wires (other than properly done knob-and-tube)
safe, it would be dramatically undersized for today’s
rather than with sheathed cable or conduit.
electrical needs.
electrical Wiring
269
ungrounded outlets
You can continue using two-slot, ungrounded
receptacles on general-use circuits as long as
the wires are in good condition and the connec-
tions are correctly made. most new lamp and
appliance plugs are double-insulated and are
suitable for use with ungrounded receptacles.
however, if you want to use appliances or tools
with three-pronged plugs or a surge protector at
the location, you must upgrade to a grounded
circuit. putting a two-pronged adapter on a
three-pronged plug is unsafe.
Unstapled cable and unsecured
boxes can be inadvertently yanked
assessing The
and stress electrical connections. If
CondiTion of Wiring
you see work this sloppy, suspect
substandard wiring throughout
Cables may be visible as they near the service
the house.
panel and as they run through attics and base-
ments. If there are covered junction boxes, care-
fully remove the covers and examine the wire
splices inside—without touching them. You can
also turn off power and pull a few receptacles out
to better examine the wires.
Deteriorated sheathing is a potential shock
hazard, so note brittle fiber insulation and bare
wire, but avoid touching it. If cable sheathing has
been chewed on by mice, rats, or squirrels the
cable should be replaced.
NM cable (cable protected by nonmetallic
sheathing) must be stapled within 8 in. of single-
gang boxes that don’t have cable clamps, and
within 12 in. of other boxes, and supported by
stapling or another method at least every 41⁄2 ft.
(54 in.). A cable running through a drilled hole is
considered supported. Sagging wire is hazardous
because it can get inadvertently strained, jeopar-
dizing electrical connections. Likewise,
all boxes must be securely mounted. All NM
cable entering metal boxes must be gripped
b
y cable clamps. Single-gang plastic boxes do
not require the strain relief of cable clamps, but
double-gang (and larger) plastic boxes have inte-
gral plastic tension clips that afford some strain
relief on cable.
Small-gauge aluminum wiring (10 or
12 gauge) is a fire hazard unless it is correctly
Some old houses still have knoband
spliced to a copper wire with a COPALUM® con-
tube wiring, which doesn’t necessarily
nector or terminated to CO/ALR-rated outlets
need to be replaced. Have it tested to
and switches. If it is incorrectly terminated in a
make sure it’s still in good shape.
copper-rated only device, the two metals will
270 Chapter 11
expand and contract at different rates each time
the circuit is under load. This can lead to loose
assessing a Circuit’s Capacity
connections, arcing, overheating, and house fires.
Aluminum to aluminum splices require special
To recap briefly, electricity, impelled by voltage, flows from the power source.
splicing techniques, either COPALUM connectors
( Amperes are the rate of electron flow.) along the way (at outlets), it encounters
or another listed and approved method.
resistance and does work. ( Watts are a measure of power consumed.) it then returns
Wire splices (whether copper to copper, cop-
to the power source, its voltage reduced or spent.
per to aluminum, or aluminum to aluminum)
or, expressed as mathematical formulas:
must be housed within a covered junction box or
watts = voltage x amperes
outlet box. Wires that are spliced outside a box or
inside an uncovered box can be a fire hazard
amperes = watts ÷ voltage
because of the dangers of arcing. Loose connec-
To determine the capacity of a circuit you want to extend, identify the circuit
tions not contained in a cover box can easily
breaker controlling the circuit and note the rating of the breaker. if it’s a general-
ignite combustibles nearby because arcs
purpose circuit, the breaker will probably be 15 amp or 20 amp. a circuit controlled
approach 2,000°F.
by a 15-amp breaker has a capacity of 1,800w (15 amp x 120v); one controlled by a
Knob-and-tube wiring, although outdated,
20-amp breaker has 2,400w.
is usually safe unless individual wire insulation
The total wattage of all loads on the circuit (including the extension) must
Renovation 4th Edition Page 63