Put an outlet where you need it
Until someone comes up with a better idea, we're stuck with plugging lamps into
outlets to get light. But what if you want a lamp in the middle of the room where there's no outlet? You don't have to resort to ugly and dangerous extension cords. We'll show you how
easy it is to put the power where you need it by installing a handsome, stampede-proof, moisture-proof outlet in your floor (assuming your floor's not concrete!).
Cutting in and mounting the steel outlet box is a
job anyone with basic carpentry skills can handle.
Connecting the power is a little trickier because it
requires you to locate a suitable circuit and make
electrical connections. If you're uncertain how to do
it, consult a basic house wiring book or a local electrician
Before starting any electrical work, contact your
electrical inspections department for a permit. A
permit fee is a small price to pay for the assurance
that the wiring is safe, and you might even get some
free advice from the inspector. (See Top 10 Electrical Mistakes to see some common mistakes to avoid.)
Besides basic tools like a hammer, tape measure
and screwdrivers, you'll need a drill and a 3/32-in.
bit, 3/8-in. and 5/8-in. spade bits and a jigsaw. You'll
also need a needle-nose pliers, a pocketknife or utility
knife, a wire stripper and a voltage tester.
If you're pulling power from an existing junction box or receptacle, check the color of the bare wire ends. If they're gray rather than dull brown, they're made of aluminum rather than copper. Call in a licensed electrician to connect the old aluminum wires to the new copper wires.
Buy a special floor assembly – a regular wall outlet won't do
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Photo 1: Find a location
Measure from a reference point, such as the
radiator heating pipes shown, to locate the floor outlet so it
falls between the 2x10 floor joists. Then
use an 8-in. straight length of clothes hanger, snipped off at
an angle to form a point, as a locator bit. Start the drill
slowly while holding the hanger to keep it from whipping
around as you drill through the flooring.
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Photo 2: Find the clothes hanger bit
Find the protruding clothes hanger in the
below. If there
are no obstructions
and this is
a suitable spot
for a floor outlet,
The National Electrical Code requires floor outlets
to be a part of an approved assembly consisting of a
metal box, gasket seal, special receptacle and strong
cover plate with a moisture-proof cover. You can't
just mount a regular wall outlet in the floor. The first
time someone stepped on it, it would break. Besides,
mopping a floor around an outlet that doesn't have
a moisture-proof cover could cause corroded connections,
or worse, give you a lethal shock.
The residential floor box assembly we're using may be available at home centers, but if you can't find one there, you'll find a selection at a local electrical supply
store that caters to professionals. You can find a Tamper Resistant Receptacle Floor Box Kit online, available through our affiliation with Amazon.com.
In addition to the floor box assembly, buy
enough cable to connect the outlet to the power
source. With a few local exceptions, you can use
plastic-sheathed cable (technically called Type
NM-B). Use 14-gauge wire if the circuit you're connecting
to is protected with a 15-amp fuse or circuit
breaker (12-gauge wire for 20-amp circuits).
You'll also need at least one plastic cable clamp
(Photo 6), wire connectors (Photo 10), 1/2-in.
plastic staples (Photo 10) and 1/2-in. x No. 4
Pick a location you can reach with the power cable
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Photo 3: Cut a hole for the box
Outline the outlet box on
the floor. Drill
two 3/8-in. holes
at the corners
where the screws
the sides of the
metal box and
two more where
the outlet mounting
Now use a jigsaw
with a wood-cutting
complete the box
masking tape to
protect the floor
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Photo 4: Make the box flush
Chisel shallow notches
to accept the mounting ears. Then place
the box in the hole and drill 3/32-in.
pilot holes for the four mounting
screws. Determine where the wire will
enter the box and remove the appropriate
round metal knockout plug with a
needle-nose pliers. Screw a No. 10-32
green grounding screw into the
threaded hole in the bottom of the box.
Then attach the box to the floor with
the 1/2 in. No. 4 flathead screws.
You can put a floor outlet anywhere, but getting
the cable there can be tough. So keep routing
problems in mind when you choose a location.
Floors over unfinished basements or crawlspaces
are easy to reach from below. Concrete floors are
tougher because you have to cut a trench to the
nearest power source. Floors with a finished ceiling
below present a challenge that can usually be
overcome with some ingenuity. See Fishing Electrical Wire for details on how to pull cable through finished walls and ceilings.
Locate the floor joists before you cut the outlet
hole. Use heat vents, cable or plumbing pipes that
penetrate the floor and are visible from below as
reference points. Drill a small hole through the
floor (Photo 1) where you intend to place the
outlet and locate the bit from the open ceiling
below. If you drilled directly over a joist, you
won't be able to see the bit. Move over a few
inches and try again. Patch the misplaced hole in
the floor with matching wood putty. We used a
cut-off clothes hanger as a drill bit because it's
cheap, handy and easy to spot from below. This
homemade clothes hanger bit is a must for carpeted
floors because the smooth sides won't catch
the carpet fibers like a regular drill bit.
Find a circuit to supply power
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Photo 5: Run the cable
Run plastic-sheathed cable from
the floor outlet
in the next step for
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Photo 6: Lock the wires into the box
Attach the cable to the new
box. First slit the
with a utility knife or
special slitting tool
to expose 12 in. of
the enclosed wires.
Then secure a plastic
cable clamp to the
1/4 in. of the plastic
sheathing to extend
beyond the clamp.
Push the wires into
the box and snap the
cable clamp into the
knockout hole. Now
secure the cable
within 12 in. of the
metal box with a
plastic cable staple.
Most open ceilings have light-fixture boxes and metal
or plastic junction boxes where a number of cables are
joined. Both offer potential sources of power for your
floor outlet, but a ceiling light box like the one shown
(Photo 9) that's switched with a pull chain rather than
a wall switch is most likely to contain “hot” wires suitable for connecting the floor outlet.
Turn off the circuit breaker or unscrew the fuse
that controls the circuit you've chosen. If your light fixture
box is like ours, just turn on the light and have
a helper watch it as you switch off the circuit breakers
one at a time until the light goes out. Leave this circuit
breaker switched off.
If the electrical junction box you've picked doesn't
have a light fixture, you'll have to use a voltage tester
to determine which circuit breaker or fuse to turn off.
This process can be complex. If you don't have electrical
experience or are unsure how to do this, don't
hesitate to enlist the help of a licensed electrician.
A word of warning is in order here. Some electrical
boxes contain more than one circuit. Before doing
any work in the box, test all the wires in a box with a
simple neon voltage tester (Photo 9) to make sure
The electrical code requires two additional steps to
- Determine if the circuit you want to use can handle
the additional outlet without overloading. Do this by
shutting off the circuit at the main panel. Then go
through the house turning on lights and other electrical
items. Add up the wattage for everything that
doesn't go on, including things that are normally
plugged in, such as stereos and televisions. Then add
the wattage of the lamp you'll be plugging into the
floor outlet. The National Electrical Code (NEC)
allows a total of 1,800 watts for a 15-amp circuit; 2,400
for a 20-amp circuit. The amp rating of the circuit is
printed on the circuit breaker or fuse. If the total
wattage exceeds these amounts, you'll have to find a
new circuit. Also, as a rule of thumb, don't use a circuit
if it has any device drawing more than 7.5 amps
either plugged in or directly wired to it.
- To figure out if there's enough space in the box for the minimum box size required by the NEC, add: 1 for each hot and neutral wire entering the box, 1
for all the ground wires combined, 1 for all the
clamps combined, and 2 for each device (switch or
receptacle) installed in the box. Multiply this figure
by 2 for 14-gauge wire and 2.25 for 12-gauge wire
to get the minimum box volume in cubic inches.
Plastic boxes have their volume stamped inside.
Steel box capacities are listed in the electrical code.
Call the electrical inspector for that information. If
the box you want to use isn't big enough, add a box
extension or replace the box with a larger one. For more information on sizing an electrical circuit, see Preventing Electrical Overloads.
The electrical code prohibits any connections
to “dedicated” circuits, such as 20-amp small-appliance circuits in kitchens and dining areas,
20-amp laundry circuits and 20-amp bathroom circuits.
If you're unsure about your circuit, ask the electrical
A first-rate electrical job mostly means getting the details right
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Photo 7: Wire the receptacle
Snip off the wires so they're at least 6 in. long and
protrude from the top of the metal box at least 3 in.
Strip 5/8 in. of insulation from the black and white
wires with a wire stripper. Connect the bare ground
wire to the metal box by looping it once in a clockwise
direction around the green grounding screw
and tightening the screw. Loop the end of the same
bare grounding wire clockwise around the grounding
screw on the receptacle and tighten the screw.
Connect the black wire to the brass screw and the white wire to the silver screw.
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Photo 8: Add the cover
Mount the receptacle to the outlet box. Fold the wires neatly
and push the outlet into the box. Screw the outlet to the metal box
with the machine screws. Then position the foam gasket over the
receptacle and attach the brass cover plate with the small cover plate
screws. Screw the brass plug with the rubber O-ring seal into the
hole to protect the outlet from dirt and moisture when it's not in use.
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Photo 9: Test for live wires
Switch off the circuit breaker or remove
the fuse at the main panel to disconnect the power to the wires in
the junction box you're hooking up to. Double-check that the
power is off by holding one lead of a voltage tester against one
light-fixture terminal screw and the other against the bare copper
grounding wire. Check the other terminal the same way. If the
tester lights up, the power is still on. Do not continue until you find
and turn off the correct circuit breaker.
4 of 4
Photo 10: Connect the new wires
Punch out one of the knockouts in the plastic or
steel junction box. Push the wires into the box
until 1/4 in. of the sheathing is
visible inside of the box, then clamp them in place. Remove the wire connectors
one at a time. Line up the end of
each new wire in turn with the
ends of the existing wires and
reconnect them with a new wire
connector. Connect the bare
ground wire to the ground wires,
the neutral white wire to the neutral
white wires, and the black
wire to the red or black hot wire
Photos 2, 3 and 4 show how to cut in and install
the steel outlet box that's included with the floor
outlet assembly. Mount the box. Then run the
cable from your power source to the floor outlet.
Follow these rules if you have to drill
- Avoid drilling holes in the center one-third of
the span or length of the floor joist.
- Holes must be a minimum of 2 in. from the top
and bottom edge of the joist. Staple the cable with
special 1/2-in. plastic NM cable staples every
4-1/2 ft. where it runs along the joist. (TIP: For a
neater, easier job, unroll the cable and remove the
twists before installing it.) Don't staple either end
of the cable yet, and leave at least 1 ft. of extra
cable on each end.
Photos 6 – 8 show how to wire the new outlet.
For more information, see How to Make Safe Wire Connections.
When the floor outlet connections are complete,
move to the basement and connect the other end of
the wires to the power in the ceiling box (Photos 9
and 10). You'll have to remove a “knockout” plug
with a screwdriver or needle-nose pliers to provide a
hole for the cable to enter the box. Attach the cable
to the box with a cable clamp. Many boxes have
built-in clamps. Connect the wires as shown in
Photo 10. Match the wire connectors you're using to
the number of wires being connected. Red connectors
like the ones we're using can usually connect up
to five 14-gauge or four 12-gauge wires, but check
the manufacturer's specifications on the package to
be sure. Replace the light fixture or cover plate to
complete the wiring job.
For outlet installations on carpeted floors, the top
edge of the outlet box must be flush with the carpet.
Flipping the outlet ears over before mounting the
box is one easy way to accomplish this.
Your new floor outlet is strong enough to withstand
occasional abuse, and with the cover and gaskets
in place you'll be able to damp-mop the floor
without worrying about getting shocked or damaging
the wiring. Keep a record of the manufacturer's
name in case you lose the cover and have to order a