The Fiber Optic Association - Tech Topics
EAI/TIA
568 For Fiber Optics
The EAI/TIA
568 standard for premises
cabling is used by most manufacturers and users of premises cabling
systems in the US. Internationally, IEC/ISO 11801 is very similar,
although there are differences in various countries.
TIA-568 has been under continual revision since its inception.
The current version is "568 C".
It includes some major changes from earlier versions for fiber
optics. Since its beginnings in early 1990s,
additions and changes included:
Fiber Optic Cable Performance Standards
568 B3 added
50/125 fiber as an
acceptable type and specifies the performance of cabled fiber
as follows:
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3500 (OM4) |
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Note that
these specs are quite
conservative, compared to what is routinely available in the
marketplace. The spec notes also
that the cable manufacturer
can use the fiber manufacturer's data on bandwidth, so they do
not have to test it.
Hybrid Cables
The standard
notes that hybrid
cables are permitted, with markings per ANSI/EIA/TIA-598-A. (
Hybrid cables contain both multimode and singlemode fibers.)
Premises Cables
Horizontal cables with 2-4 fibers require a 25 mm bend radius after installation or 50 mm while being pulled with a tension of 50 pounds (222 N).
Other
premises cables require
a bend radius of 10 times the cable outside diameter unloaded
and 15 times the OD when under the maximum rated pulling tension
for that cable.
Outside Plant Cables
The standard calls for water-blocked cables with a minimum pulling tension of 600 pounds (2670 N).
Minimum bend radius is 20 times the cable diameter under max rated pulling tension and 10 times unloaded.
Drop Cables
The standard
adds a definition
for "drop cables," low fiber count cables used to connect
high fiber count cables to smaller fiber count cables or patchcords
in a single location. These cables must withstand 300 pounds pulling
tension (1335 N).
Connectors
and Connecting Hardware
Any connector
design is permitted
as long as it has a FOCIS document (Fiber Optic Connector
Intermateability
Standard). All small
form
factor connectors with FOCIS
documents are acceptable.
Color Codes:
Multimode connectors
are beige for 62.5/125 fiber, black for 50/125 fiber, singlemode are
blue, angle-polished singlemode are green, and outlets are also color
coded
accordingly. Cable color codes are the same as TIA-598.
Duplex
connectors are keyed and
are always crossover - that is Position A of one connector
connects to Position B on the other end! Patchcords have this
feature too, to permit correct connection of transmitters and
receivers! Polarity for multipin connectors (MTP/MPO) are specified in
several different versions and are very confusing.
Outlet boxes
must have provision
for termination of at least 2 fibers.
Patch panels
and outlets must
provide unique identification for the connecting cabling.
Connector
Mating Loss:
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Remember these
connector losses are maximum values. The loss
is high to allow prepolished/splice connectors which have higher loss
than adhesive/polish connectors. Users may specify lower loss for
installations if agreed upon by all parties involved. As of 2012,
options to lower connector losses, perhaps in a statistical manner, are
being considered.
Notes:
Loss is tested per FOTP-171, single cable reference.
Maximum loss
spec holds over temperature
(0-60C), humidity (95% @ 40C), impact, pull strength of coupling
(7.4 lb./33N), durability (500 matings), cable retention (11 lbs./50
N straight, 4 lbs./19N at 90)flex and twist.
Splices
Fusion or mechanical splices shall not have a loss of more than 0.3 dB. Multimode splices must have a return loss of better than 20 dB. Singlemode splices must be better than 26 dB ORL for general applications, 55 dB ORL for CATV broadband analog video.
(C) 2004-12 The Fiber Optic Association, Inc.
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