General
- Only
one wire can be put underneath a screw terminal unless the
terminal is specifically designed to accommodate two or more wires.
- White
wires go to the silver-colored screws, black wires go to the
brass-colored screws, and green wires go to green-colored
screws.
- With nonmetallic sheathed cable, the
ground wires must
be connected to the ground screw on the receptacle. If the box is
metal, the ground wires must also be connected to it.
- If using metal boxes and metal conduit,
ground wires
do not need to be run through the conduit. The conduit serves as the
ground connection. However, a ground
wire must be connected from the receptacle's ground screw to the metal
box.
(Some receptacles are specially designed to provide reliable contact
with the box, and for these, the ground wire is unnecessary.)
- From the point where wires enter a box to
the end of the wires, the distance must be at least 6 inches.
- From the outside edge of a box to the end
of the wires, the distance must be at least 3 inches.
EMT--Electrical
metallic tubing
- This is the type
of conduit we've been using. It has
thinner walls than RMC (rigid metallic conduit) or IMC (intermediate
metal conduit).
- Must be supported within 3 ft. of each box.
- Must also be supported at least every 10 feet.
RNC--Rigid nonmetallic conduit
- Basically, this
is PVC plastic conduit (as it's
typically called), and it's very popular. You can bend PVC conduit if
you have an appropriate heat source, but the most common method is to
buy ready-made bends.
- This type of
conduit is fastened together with glue,
just as with PVC water pipe.
- The conduit must
be supported within 3
feet of a box,
and every 5 feet
thereafter.
- Certain
restrictions apply to PVC conduit. The main ones are as follows:
- It can't be
used to support luminaires (light
fixtures)
- It must be
protected from physical damage (such as
things bumping into it). This is especially true if cold temperatures
are likely (which make the conduit brittle).
- It can't be
used where temperatures will exceed 122
degrees (unless a special type of high-temperature conduit is
used)
- It can't be
used in theaters and similar locations.
Nonmetallic-Sheathed Cable
- Also referred to
as Romex (a popular brand name).
- Must be supported within 1 ft. of each box.
- Must also be supported every 4 1/2 ft.
- Can't be used for
the following locations:
- Certain types
of buildings other than one- and
two-family dwellings (where the cable is permitted).
- Commercial
garages
- Theaters
- Motion picture
studios (probably because of the flammability of props and film)
- Storage battery
rooms
- On elevators
- In poured cement
- Hazardous
locations
Communications (Phone and Alarms) and
Computer Network Wiring Within Buildings
- Separated at least 2 inches from power
wiring.
- Cannot be run inside ducts used for
removal of dust or vapor.
- Can be run inside cooling and heating air
ducts (plenums) provided the cable is of a type specified
for this use.
Metal conduit can also be used, however flexible metal conduit is only
permitted in lengths of 4 ft. or less.
- Certain types of buildings have
restrictions as to the
types of cables that can be used (mainly due to the issue of
flammability).
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