ESTIMATING
WIRE NEEDS:
To estimate the amount of wire or cable you will need for a project,
measure the distance between the new outlet and the power source
Add an extra foot for every connection you will make. Then, to provide
a margin for error, add 20% to this figure.
For example,
if you measure 12' between a new and existing receptacle , add another
2' for the connections, making a total of 14'. Then add 20% (about
3') to the total. To do the job , start working with 17' of cable.
The same formula is used for wire, with the exception of lamp/appliance
cord.
MECHANICS
OF WIRING:
The mechanics of wiring - attaching the wire to switches, outlets,
and fixtures - are fairly simple: cutting wire, stripping insulation,
and connecting wires to the proper terminals.
To prepare
nonmetallic sheathed cable:
- Cut
the cable to the proper length. Use lineman's pliers or a hacksaw.
- Cut
the sheath insulation. Place the cable on a flat surface , such
as a workbench. Measure about 8 " from the end of the cable and
make a mark. Then insert the cable in a cable ripper at the marked
pint. Press the cable ripper together with your fingers and pull
the cable through the ripper to the end of the cable.
If
you use a knife instead of a ripper, start cutting the sheath,
being extremely careful not to cut the insulated wires inside
the cable . It may take several shallow cuts with a knife to part
the plastic sheath. If you damage the wire, cut that part off
and start again.
- Trim
the sheath insulation With your knife to trim away the excess
sheath material at the first cutting mark.
- Cut
the wire insulation. With the wire strippers, remove about 1/2"
to 3/4" of insulation from the black-insulated power wire, the
white-insulated neutral wire, and the green or green and yellow
grounding wire (if it is insulated). As you work, check to make
sure that you did not cut the wire insulation with the ripper
or knife as you removed the sheath insulation. If you did cut
the insulation on the wires, trim off all wires at the cutting
mark and start over. The insulation on the wires inside the cable
must be completely sound in order to prevent hazards, such as
an electrical short circuit or, worse, an electrical fire.
To
Prepare Metal-Armored Cable-
- To
strip armored cable, make a hacksaw cut about 8 " from the end
of the cable. Firm the cable in a vise, or hold it fat on a rigid
surface. Push the hacksaw diagonally across a crowned section
of the cable (not in a groove).
Hacksaws cut on the forward stroke if the blade is properly mounted
on the frame of the saw Use some pressure, but not a lot on the
saw Be careful to prevent sawing too far through the cable and
cutting the wires inside the cable.
- When
the cut is made, snap the cable at the cut with your hands. It
will break. Then insert a BX plastic collar around the cut to
protect your hands.
- Strip
insulation on the wires inside the cable the same way as previously
detailed.
SPLICING
AND JOINING WIRES:
A good connection should be mechanically and electrically secured
without any soldering. You should regard soldering or splicing devices
as extra protection against insecure connections.
A spliced
wire must be as good as a continuous conductor. While there are
many different splicing techniques, the two-wire splices shown in
are the most common.
Wires
may also be connected by using solderless connectors such as:
Clamshell
Connector- This connector is molded from a single piece of plastic
with a pointed metal insert. Simply insert the wires and close the
lid; the metal points will make a good contact with the metal wire.
Wire
Nut- This connector is used to splice two stranded wires. Strip
away about 1/2 to 1 " of the insulation on each wire, twist diem
together, and screw on the nut. Then wrap the wire nut and an inch
or so of the wire wt electrician's tape.
Split
Bolt Connectors- This connector is ordinarily used for heavy,
stranded wires. Make sure the connector is made of a metal that
is compatible with the wire to prevent corrosion. Wrap bare wires
with electrician's tape.
By code, wire cannot be spliced outside a junction, switch, or outlet
box.
CONNECTING
TO A TERMINAL:
To connect to a terminal, remove the insulation from the wire and
twist the end into an open loop; hook the loop around the terminal
with the opening to the right. Then tighten the screw, making sure
that the wire is in full contact with the screw and contact plate.
The screw must be tight.
