secure cable, install nail plates where needed.
stripping 9 in. of sheath off the
from there toward the first box of each circuit.
cable (use the span of your hand
These circuit segments are called “home runs.”
Fishing cable. Most electricians hate fishing
or length of your lineman’s pliers
Once they’ve run cable to all the home-run boxes, wire behind walls or ceilings. It can be tricky to
to judge this). for inspectors,
they move a reel next to each box and continue to find the cable and time consuming to patch the
short, stubby wires are the mark
pull cable outward until they reach the last box.
holes in plaster or drywall. If you’re adding a box
of an amateur.
When doing remodel wiring in a house with a
or two, try fishing cable behind the wall. But if
crawlspace, however, electricians often start at
you’re rewiring an entire room, it’s probably fast-
292 Chapter 11
running Cable to a neW outlet
Fishing cable to a new outlet can
running Cable to a new outlet
be time consuming and tedious.
Top plate
Ceiling joist
often, it’s quicker and easier to
zzzzzz
cut back sections of drywall to
New cable
the nearest studs or ceiling
joists. With a stud bay exposed,
you can pull wire in a hurry and
staple cable to studs.
New ceiling box
New
switch
box
Existing
receptacle
Cut back drywall
to middle of studs.
A swivel kellum grip slides over the
end of the cable and prevents it from
twisting as it’s pulled.
P r O t I P
Put a piece of red tape, or
even better, tie some yellow
“caution” tape around the stud
at eye level on the first box in
each circuit (the “home-run”
box) to ensure that you run cable
from it to the panel. This also
helps with planning the home-
run cable pulls. on a complex job
with many circuits, you might
run cable between all the outlets
in a circuit but forget to install
To fish cable to a new outlet, insert a flex bit into the new
Pull back after a helper below the floor attaches the cable.
the home-run cable that will
opening and drill down through the floor or bottom plate.
energize the circuit. not some-
thing you want to discover after
the drywall’s up.
electrical Wiring
293
er to cut a “wiring trench” in the wall (see p. 297). to disconnect the wires to the receptacle and
P r O t I P
Before cutting into or drilling through a wall,
remove it. Then remove the box, which may
however, turn off power to the area.
require using a metal-cutting reciprocating-saw
if you’re remodeling, keep
If you’d like to avoid fishing altogether, see
blade to cut through the nails holding the box to
in mind that every finish surface
“Installing a Wireless Switch” on p. 308.
the stud. Fish a new cable to the location, and
you drill or cut into is a surface
insert the new and old cables into a new cut-in
that you’ll have to repair later.
Fishing cables behind finish walls. If you’re
box. Secure the cut-in box to the finish surface,
so minimize cutting and drilling,
adding an outlet over an unfinished basement,
splice the cables inside the box, and connect pig-
but realize that sometimes you
fishing cable can be straightforward. Outline and
just have to open a wall to fish
tails from the splice to the new receptacle.
cut out an opening for the new box, insert a flex
a cable in a reasonable amount
bit into the opening, and drill down through the
Fishing cable to a ceiling fixture. Fishing cable
of time.
bottom plate. When the bit emerges into the
to ceiling fixtures or wall switches is usually a bit
basement, a helper can insert one wire of the new complicated. If there is an unfinished attic above
cable into the small “fish hole” near the bit’s
or a basement below, run the cable across it, then
point. As you slowly back the bit out of the box
route the cable through a stud bay to the new box
opening, you pull new cable into it. No fish tape
in the ceiling. To run cable to a ceiling light, drill
required! The only downside is that the reversing up through the fixture location using a 3⁄16-in. by
rEMOvInG A WAll BOx drill can twist the cable. This problem is easily
12-in. bit to minimize patching later. Use a bit at
avoided by sliding a swivel kellum (see p. 293)
least 6 in. long so a helper in the attic can see it—
over the cable end instead of inserting a cable
use a longer one if the floor of the attic is covered
wire into the flex bit hole. Because the kellum
with insulation. Measure the distance from the
turns, the cable doesn’t.
bit to the wall; a helper in the attic can use that
Alternatively, you can start by removing a wall measurement to locate the nearest stud bay to
box. The closest power source is often an existing drill an access hole into. If you’re working alone,
outlet. Cut power to that outlet and test to make
loop the end of a stiff piece of wire about 1 ft.
sure it’s off. The easiest way to access the cable is long and insert it into the drilled hole; friction
After testing for voltage, remove the
cover plate, unscrew the receptacle
fishing Cable
from the box, and pull it out. Then
aCross CeIlInG JoIsts
disconnect the wires.
sometimes there is no open bay to a ceiling fixture location. In that case, you’ll have to drill across ceil-
ing joists to run cable to the top plate of the wall. use a 6-ft.-long flex bit (and a 48-in. extension, if
needed) to drill across joists. Flex bits can wander and go off target, so be patient. When the drill bit
emerges above the top plate, attach a swivel kellum grip and insert the cable and tape it to the grip.
then slowly back the drill bit out, pulling the cable to the opening you cut in the ceiling.
fishing Cable across Ceiling joists
New opening
for ceiling box
zzzzzz
Flex bit
Drill across
ceiling joists.
remove the old outlet box, drill,
fish new cable to the opening, and
splice the existing cable to the
Future cable path
new. You’ll replace the old box
with a remodel box.
Drywall cutout
at top plate
New cable
Cutout for
switch box
Cable from
existing outlet
supplies power
294 Chapter 11
To run cable to a ceiling fixture, start by drilling an
/> If you’re working alone, jam a long,
exploratory hole with a smalldiameter bit.
looped wire into the exploratory hole,
then go into the attic and look for it.
running cable from a ceiling fixture to a wall switch
means cutting access holes.
avoIdInG hot Wires
In remodels, there may be live wires behind fin-
ADDInG A rEMODEl BOx
ish surfaces. use a non-contact tester to test
receptacles, switches, fixtures, and any visible
wires. the cables feeding those devices will be
nearby. Wall receptacles are usually fed by
cables running 1 ft. to 3 ft. above. switches
often have cable runs up to a top plate; each
ceiling fixture has cable running to the
switch(es) controlling it. avoid drilling or cut-
ting into those areas, and you’ll minimize the
risk of shock.
will keep the wire upright in the hole until you
can locate it in the attic.
1. Position the box and then trace
2. After you chisel out the plaster within the outline,
If there’s no access above the ceiling and/or
the box outline onto the wall.
use a sabersaw or an oscillating multitool to cut lath.
cable must cross several ceiling joists to get from
a switch to a light fixture, you’ll have to cut into
finish surfaces at several points. To access cable
3. After fishing and pulling cable,
in a stud bay, you’ll need a cutout to expose the
secure the box to the wall. Here, box
top plate. Using a flex bit may minimize the
ears are screwed to the lath.
number of holes you must cut to drill across ceil-
ing joists. But as noted earlier, it may ultimately
take less time to cut and repair a single slot run-
ning across several joists than to patch a number
of isolated holes. Whatever method you choose,
make cuts cleanly to facilitate repairs. First, out-
P r O t I P
line all cuts using a utility knife.
insTalling reModel boxes
if you need to run cable
between new and old outlets
If existing house wiring is in good condition and
directly over each other, use a
an existing circuit has the capacity for an addi-
lightweight chain or fishing line
tional outlet, turn off the power, cut a hole in the
with a weight rather than fish
wall, fish cable to the location, and secure a
tape. The weight line or chain
remodel box (cut-in box) to the finish surface.
will be easy to snag because it
will hang freely.
This process is also called cutting-in or retrofitting
electrical Wiring
295
a box and, of course, it requires boxes with spe-
P r O t I P
cial mounting mechanisms.
Try to avoid using cut-in boxes
Cutting a wall box in plaster. Hold the new box
to house receptacles in high-use
at the same height as other outlet or switch boxes
areas like bathrooms and kitch-
in the room, and trace its outline onto the wall.
ens. Plugs repeatedly inserted
Use a stud finder or drill a small exploratory hole
and removed will cause cut-in
to locate studs or wood lath behind. Look for
boxes—and possibly, electrical
water pipes and other wires. If you hit a stud,
connections—to work loose. in
move the box. If you hit lath, keep drilling small
such locations, you’ll need to
holes within the opening to find the edges of the
expose the framing and mount
lath. If you position the box correctly, you’ll need
new-work boxes to it.
to remove only one or two lath sections.
Use a utility knife to score along the outline to
minimize plaster fractures. Remove the plaster
To retrofit a ceiling box, mark the box center onto the
within the outline using a chisel. Then cut out
ceiling, then use a finetooth hole saw. Wear a respirator
and safety glasses—this is dusty work.
the lath, using a cordless jigsaw or, even better,
an oscillating tool with a Universal E-cut blade.
As you cut through the lath strip, alternate par-
tial cuts from one side to the other to avoid
cracking the plaster. Then carefully remove the
plaster beneath the box ears so they can rest on
lath. Before inserting cut-in boxes, remove box
knockouts, insert cable clamps, strip sheathing
off the ends of incoming cable, and feed cable
into the cable clamps. If more than one cable
After drilling an exploratory hole and
enters the box, write the destination of each on
locating the box, trace the box
the sheathing. Secure the box by screwing its
outline onto the drywall.
ears to the lath.
Cutting a wall box into drywall. Adding a cut-
in box to drywall is essentially the same as add-
ing one to plaster. Start by drilling a small explor-
atory hole near the proposed box location to
make sure there’s no stud in the way.
There are a number of cut-in boxes to choose
After removing the plaster cutout, drill a hole through the
lath so you can pull cable to the box. This worker uses an
from. The most common have side-mounted ears
auger bit, but you could also use a cordless drill with a
that swing out or expand as you turn their screws.
spade bit.
Hold the box against the drywall, plumb one
side, then trace the outline of the box onto the
wall. Drywall is much easier to cut than plaster:
Simply align the blade of a drywall saw to the
You’ll have the greatest control if you
make a series of cuts before using a
line you want to cut, and hit the handle of the
utility knife or an oscillating
saw with the heel of your hand.
multitool to finish the cutout.
There is no one right way to cut out the box,
but pros tend to cut one of the long vertical sides,
then make two or three horizontal cuts across.
Then score and snap the last cut. Finish the cut-
out using the drywall saw and a utility knife.
retrofitting a ceiling box. As with all retrofits,
turn off power to the area and explore first.
Follow the mounting recommendations for your
fixture. Attach the fixture box to framing.
If there’s insulation in an attic above, remove
it from the affected area. Be sure to wear eye pro-
tection and a dust mask when drilling through
any ceiling—it’s a dusty job.
Mark the box location, and use a fine-tooth
fish cable through the hole, feed it through a connector in
the box, and screw the box to framing or blocking.
hole saw to cut through plaster or drywall. Place
296 Chapter 11
CrEATInG A WIrE TrEnCH
the centering bit of the hole saw on the exact cen-
ter of the box opening. Drill slowly so you don’t
damage adjoin
ing surfaces—or fall off the ladder.
If the ceiling is drywall, you’re ready to run
cable through the hole in the ceiling. If the ceil-
ing is plaster, cut through the lath or leave the
lath intact and screw a pancake box through the
lath and into the framing. Before attaching a
pancake box, remove a knockout, test-fit the box
in the hole, and trace the knockout hole onto the
lath. Set the box aside, and drill through the lath,
creating a hole through which you can run cable.
2.
Feed cable to the location, and fit a cable con-
To ensure a clean cutline and
facilitate patching when you’re done,
nector into the box. Insert the cable into the con-
use a utility knife to score along
nector, slide the box up to the ceiling, and secure
chalklines.
it. Strip the cable sheathing, and attach the
ground wire to a ground screw in the box. Strip
insulation from the wire ends, and you’re ready
1. Use a chalkline to mark the top and bottom lines of
to connect the light fixture.
the wiring trench.
CreaTing a Wiring TrenCh
When adding multiple outlets or rewiring an
entire room, cutting a wiring trench in finish sur-
faces instead of fishing cable behind them is
much faster. Before cutting or drilling, however,
turn off the power to the areas affected. Be
sure to wear eye protection and a dust mask.
(And before you cut into finish surfaces, see
pp. 514–517 for more about lead-paint safety.)
If there are no windows in the walls to be
rewired, cut the trench about 3 ft. above the floor
4. If walls are drywall, simply pull
so you won’t have to kneel while working. If there
out the isolated strips. If plaster, use a
are windows, cut the trench under the windows,
hammer to break out the plaster and
leaving at least 1 in. of wall material under the
expose the lath.
windowsill to facilitate repairs. If there’s plaster,
make the trench as wide as two strips of lath.
Snap parallel chalklines to indicate the width of
the trench. Then use a utility knife to score along 3. Cut along the chalklines, holding the reciprocating
each line. Scoring lines first produces a cleaner
saw at a low angle so you don’t cut into lath or framing.
cut and easier repairs.
Next, use a reciprocating saw with a demoli-
tion blade to cut through the plaster or drywall.
Renovation 4th Edition Page 69
