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There
are several classifications of cable used for twisted-pair networks.
I'll skip right over them and state that I use and recommend Category
5 (or CAT 5) cable for all new installations. Likewise, there
are several fire code classifications for the outer insulation of CAT
5e cable. I use CMR cable, or "riser cable," for most
of the wiring I do. You should also be aware of CMP or plenum
cable (a plenum is used to distribute air in a building). You
may be required by local, state or national codes to use the more expensive
plenum-jacketed cable if it runs through suspended ceilings, ducts,
or other areas, if they are used to circulate air or act as an air passage
from one room to another. If in doubt, use plenum. CMR cable
is generally acceptable for all applications not requiring plenum cable.
CAT 5e wire is available in reel-in-box packaging. This is very handy for
pulling the wire without putting twists in it. Without this kind
of package or a cable reel stand, pulling wire is a two-person job.
Before the advent of the reel-in-box, we used to put a reel of wire
on a broom handle to pull it. One person would hold the broom
handle and the other would pull and measure the cable. You will
produce a tangled mess, if you pull the wire off the end of the reel.
Stranded wire patch
cables are often specified for cable segments running from a wall jack
to a PC and for patch panels. They are more flexible than solid
core wire. However, the rational for using it is that the constant
flexing of patch cables may wear-out solid core cable--break it.
I don't think this is a real concern in the average small network.
For example, I have one solid core cable going to my work bench.
It has probably flexed and average person's lifetime of flexes from
the many many times I have connected customer computers to my network.
Also, stranded cable is susceptible to degradation from moisture infiltration,
may use an alternate color code, and should not be used for cables longer
than 3 Meters (about 10 feet).
Most of the wiring
I do simply connects computers directly to other computers or hubs.
Solid core cable is quite suitable for this purpose and for many home
and small business networks. I find it also quite acceptable
for use as patch cables. You might consider a stranded wire patch
cable if you have a notebook computer you are constantly moving around.
CAT 5e cable has
four twisted pairs of wire for a total of eight individually insulated
wires. Each pair is color coded with one wire having a solid
color (blue, orange, green, or brown) twisted around a second wire with
a white background and a stripe of the same color. The solid
colors may have a white stripe in some cables. Cable colors are
commonly described using the background color followed by the color
of the stripe; e.g., white-orange is a cable with a white background
and an orange stripe.
CONNECTORS.
The straight through and cross-over patch cables discussed
in this article are terminated with CAT 5e RJ-45 modular plugs.
RJ-45 plugs are similar to those you'll see on the end of your telephone
cable except they have eight versus four or six contacts on the end
of the plug and they are about twice as big. Make sure they are
rated for CAT 5e wiring. (RJ means "Registered Jack").
Also, there are RJ-45 plugs designed for both solid core wire and stranded
wire. Others are designed specifically for one kind of wire
or the other. Be sure you buy plugs appropriate for the wire you
are going to use. I use plugs designed to accommodate both kinds
of wire.
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