Installing An "Old
Switch Or Outlet Box
Bruce W. Maki,
When adding wiring to an existing house it is not practical to
remove large sections of drywall just to mount electrical boxes and
run cables. There are several types of electrical boxes
available that attach directly to drywall or plaster and are used in
conjunction with cable that simply dangles inside the wall cavity.
||This is an "old work" electrical box, also
called a "remodel" box. It is designed to clamp to the
wallboard, as opposed to a "new construction" box which is
nailed to a wall stud.
||There are two clamp tabs on this type of old
work box. The box is inserted into the opening with the tabs
retracted, and then a simple turn of a screwdriver moves the tab
behind the wallboard. Continued tightening of the screw makes
the tab clamp onto the wallboard.
||Many years ago I made this template from a piece
of cardboard, so I would be able to quickly layout the shape of
the drywall cutout.
The odd shape that I use is not necessary. It is possible to make
the hole slightly larger (imagine taking the uppermost and lowermost
horizontal lines and extending them until they met the vertical
sides), but the hole I use is the smallest shape possible. This
makes for a stronger drywall surface around the box, so there is
less chance of the wallboard crumbling and leaving the box with
insufficient material to grab on to.
|I used a stud finder to locate the stud near an
existing outlet. I will be tapping into the power at that
outlet, and my new box, which is for a light switch, will be
just above it.
With old work boxes it is important to stay away
from studs. It is possible to place a box right beside a stud,
but I try to stay a few inches away.
||For this switch box I made a mark 42 inches
above the floor, which indicates the bottom of the new box. This
height is also commonly used for receptacles over kitchen
If I was installing a receptacle in a normal situation, I
would make the mark 12 inches above the floor. Some
electrical codes may dictate these heights.
|I placed the template on the height mark and
drew the shape of the cutout.
||I drilled a hole at each corner, using a 3/8"
diameter spade drill bit.
|I cut along the lines with a hand saw.
This little saw is pretty neat... it folds up, so it can be
easily stored in a pocket or a tool pouch. And it uses
standard reciprocating saw blades, so the blade can be
replaced when worn out. I got it at KMart, of all
places, for about $10.
Actually, this saw must be magic. I lost it twice while
cross-country skiing (I used it to trim tree branches on some trails
through the woods) but I found it both times... just laying in the
snow. There's something to be said for brightly-colored tools.
||Aha! There's a wire behind that wall.
This is why I prefer to use a hand saw for cutting these
holes. A power saw (such as a jig saw) can easily slice up
wires that lurk beneath the surface.
|I slipped the box into the hole to test the fit,
but the box cannot be left there just yet. I need to run the
cable through the hole first.
||I went into the attic and slipped a new cable
down through the hole I drilled in the top plate. It was easy to
find this new cable... I just reached into the hole and pulled
I made a "J"-shaped hook in the cable so I could go back up
to the attic and pull the cable back a bit (I had fed too
much down the hole). This hook got caught on the wallboard
and told me that I had pulled back enough. This is the kind
of trick you have to do when working alone.
|Then I ran the new cable up from the receptacle
below. I slipped both cables into the box, using separate
Note how I made both cables come in from the top. It is
much easier to work with these boxes if all the cables
approach from the same end, top or bottom.
||The box was pushed into place and the screws
were tightened carefully.
This type of old work box uses special spring-loaded clamping
tabs to prevent the cable from being pulled out of the box.
These tabs are basically one-way devices, and allow the cable to be
pulled further into the box, but not out.
Electrical codes generally require that cable be secured to the
framing within 12 inches of the junction box. These old work
boxes meet that requirement (as far as I understand) by securing the
cable right at the box. It is not necessary to cut holes in
the wall to secure the cable at other places.
But remember, I'm not an electrician. I have done several major
electrical projects, permitted and inspected, but I am not an
expert. Everybody who attempts home wiring should buy one or two
decent books on basic electrical wiring.
Electrical Work And Permits:
Electrical modifications such as this light installation may
require a permit.
Some local Building Departments allow homeowners to make minor
changes in electrical systems without a permit. We recommend that
you call your local Building Department and find out if a permit is
required for a small alteration.
Back To Top
- Cordless Drill/Driver
- 3/8 Spade Drill Bit
- Small Saw
- Stud Finder
- Tape Measure