of Structured Cabling
Training Programs and Equipment
- Installing Wiring
- Everybody knows how to pull
wire, right? Wrong! Mistakes in installation work can be difficult
to detect. A mistake that could keep the entire system from working
might not show up at all until the system is completely installed
and turned on.
- The performance of the cabling
network is heavily dependent on the installation. The components
used in structured cabling installation have been carefully designed
and exhaustively tested to meet or exceed the requirements of
EIA/TIA 568 for performance at 100-250 MHz. If the cable is not
properly installed, performance will be degraded.
- Just like we keep harping on
keeping the twists right down to the terminations, there are
things you must realize to maintain the performance of Cat 5e
/6 wire you paid for! First of all, pulling tension must be less
than 25 pounds. That's not very much! Pulling at higher tension
can stretch the cable and affect the twists in the pairs, and
it's those twists that make the cable perform well at high frequencies.
Likewise, kinking the cable by letting it get twisted or pulled
around sharp corners can cause permanent damage. Damaged cable
will probably not pass crosstalk tests.
- Most cable boxes are designed
to allow easy pulling directly from the box. Gather up several
boxes and pull a bunch of cables at once. Tape them together
and attach a pullstring or just feed them along by hand.
- You can pull from the telecom
closet or to the closet, whichever is more convenient in the
install you are doing. You can also pull to consolidation points
then out to individual outlets or vice versa, instead of pulling
the bundle of cables all the way.
- One item to remember is there
is usually 1,000 feet (about 300 meters) of cable in each box.
Each cable is also marked with a distance every few feet so you
can keep track of length by reading the distance off the cable.
Before you pull any cable from the box, find the distance
marked on the cable and write it down on top of the box!
That way, you can calculate the length of each cable you pull
and more importantly, the amount remaining in the box! It's not
good to start pulling a cable and find out it's not long enough!
- Likewise, mark every cable with
a location it's going to. Mark it on both ends! You will save
lots of time making the correct connections, recording test data
and keeping records for moves and changes. A fine tip permanent
marker will mark the cable neatly.
- Cat 5 e/6 should be installed
on special hooks, bridle rings or cable trays that limit its
bend radius and stress to preserve the performance. You cannot
lay the cable on top of ceilings or hang from the drop ceiling
hangers - most places it's against code! Penetrations of firewalls
require firestopping to restore fire retardancy. You also have
to keep the wire away from sources of interference, like fluorescent
lights and power cables.
- Power cables are also a safety
hazard. Although this cable is called "low voltage,"
it runs in areas full of power cables that are a shock hazard.
If you are not familiar with electrical safety, fire safety and
inspections, I strongly suggest taking a course on the NEC (National
Electric Code) to learn about these important topics. It could
save your life!
Here is a summary of NEC references
to VDV Cabling:
|| Sound Systems
Signaling and Power-Limited Circuits
|| Fire Alarm
|| Optical Fiber
Cables and Raceways
Circuits (Telephone and LAN)
|| Radio and
|| CATV Systems
- Other safety considerations:
- -Hard hat, safety glasses, appropriate
gloves and steel toe shoes are recommended.
- -Observe ladder safety rules
- many installations require work above ceilings.
- Electrical inspectors do not
always inspect communications wiring. Nonetheless, take a moment
to check with local electrical inspectors before you do any work
in their jurisdictions. In most cases, the inspector of your
installation will be the same person who signs you contract,
although in some cases, the inspector will be a third party.
Make sure you know who will inspect your work before you give
your customer a final price. You must know what the inspector
will expect of you and what he or she will be looking for.
- Installation Tips to follow:
- -All components must be Cat5e
rated for Cat 5e performance
- -Cable must be pulled from the
reel or box without kinking
- -Cable must be pulled with less
than 25 pounds of tension
- -Use cable lubricant in conduit
- -Cable must not be pulled around
sharp corners or kinked
- -Inspect the cable routs for
surfaces that may abrade the cable
- -On riser installations (overhead
installation), try to lower the cable down, not pull up
- -Cables must be supported to
prevent stress. Cable supports should not have sharp edges that
may distort the cable
- -Cable ties must not be so tight
as to distort the jacket of the cable. They are only used to
prevent unnecessary movement of the cable, so snug is tight enough.