When planning to hook up a circuit, whether it is a new one directly from the
breaker panel or adding to an existing one, here are some general rules to
follow :
Maximum Lights Per Circuit
You are only allowed to put a maximum of 12 lights on one 15 amp circuit, but
try for between 8 and 10, if you are combining receptacles and lights.
Remember that switches dont count as outlets. Run a separate circuit for any
large appliances, pumps, and motors etc.
Mounting Boxes
Start by marking the studs where you want your receptacles, switches, and
lights to be located. Then mount your outlet boxes.
Screws are required for octagon boxes but you can use either screws or nails
for switch and receptacle boxes. The important thing to remember is to make the
boxes secure because, once the drywall is on, its hard to re-attach them if
they do work loose.
Dont forget that you must leave the boxes sticking out from the face of the
stud, slightly less than the thickness of the product that the wall will be
finished with.
Mounting Receptacles
Mount receptacles about 300 mm (12 inches) above the floor. The general rule
is that a receptacle is required for every 3.6 meters (12 feet) of usable wall
space.
You are probably curious as to what useable wall space means exactly...any
measurement from the corner of a wall to a closet, fireplace, or to where the
door swings open is considered useable wall space but, only if the wall is over
900 mm (3 feet) to begin with.
A receptacle is needed every 3.6 meters (12 feet) along a continuous wall
space so that at no time can a cord connected devise be any more than 1.8 meters
(6 feet) from an outlet. Also remember that there is no maximum number of
outlets, so make sure you have enough, and that they are placed in convenient
locations once the room is finished.
Mounting Switches
Mount switches on the inside of rooms opposite to the side that the door
opens. Make them as close as practical to the door opening, but not so that the
cover plate will interfere with the door casing.
The height is fairly flexible, but should be consistent and practical (any
where from 1.1 to 1.3 meters or 44 to 52 inches).
Maximum Wires
Attempt to start your circuit close to the panel and then move out from
there.
For a standard sized outlet box you are only allowed a maximum of five (5)
wires (excluding the bare ground wire). Keep this in mind when running your
wires, as you cannot run power into a receptacle, and then feed two outlets from
the same box. This would give you six (6) wires therefore requiring a "deep
box".
A standard octagon box used for light outlets has a maximum wire fill of
seven (7). These box fill maximums are also based on #14 gage wire which is what
you will use throughout 95% of your home.
Common Examples
Here are two examples of how to
set up a typical circuit and how you would run your wires. Refer to methods 1
and 2.
Keep in mind these are just
examples and your wiring does not have to look exactly like Ive shown. This is
just a starting point for you to begin.
Once you have an idea of how you are going to run your wires, drill all the
holes in the studs. (A 3/4" to a 1" auger bit, driven by a 1/2" drill is the
best tool for the job). Make sure to keep the holes at least 1" in from the face
of the stud, so that drywall screws or nails cannot penetrate far enough to
damage the wires.
Do yourself a favor and leave plenty of slack at each outlet. I recommend at
least 300 mm (12").
Then strip the exterior sheath back about 150-200 mm (6"-8") leaving a loop
of slack before tightening the box clamps down on the sheath. This is done to
ensure that if the wires get damaged in any way, you will still have some slack
to work with.
You are required to secure the wires with approved wire staples,
within 300 mm (1 foot) of the outlet boxes. Also, every 1500 mm (5 feet) on a
free run of wire there must be a staple. Going through a hole in a stud counts
as being secured.
Make all the
splices that you require at the "rough-in" stage, so that when you come
back to install the receptacles, switches, and fixtures, it will be clear as to
what wire goes where.
