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1st Published, Dec. 2004

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Using CAT5 for Telephone Lines, and other Media.

By: ScottMac. (www.scottmac.net)


CAT5 was design as a Multi purpose Cable, to be used in transfer variety of Information Signal.

It typical use is for Computers Network; however it is used for Telephone and other Media.

Note: It is important not to use variety of media in the same Cable since the                               Electrical fields might interfere one with the other.  

Following the standard of Pinout connection is very important, it helps in avoiding mistakes, and provides a better capacity to maintain the runs if something goes wrong in the future.

The Pinout of TIA/EIA 568a and 568b wired a jack is completely "phone compatible." 

For Telephone lines:

Pair 1 is the blue pair on pins 4 & 5, which corresponds to telephone line 1
Pair 2 is the (green or orange) pair on pins 3 & 6, which corresponds to telephone line 2
pair 3 is the (orange or green) pair on pins 1 & 2, which corresponds to telephone line 3
pair 4 is the brown pair on pins 7 & 8, which corresponds to telephone line 4

Ethernet uses pair 2 & 3 (orange and green)

Token Ring uses pair 1 & 2 (blue and (orange or green))

T1 uses pair 1 & 3 ((orange or green) and blue)

56K / DDS uses pairs 3 & 4 ((orange or green) and brown)

ATM uses pairs 3&4 (for 155 or 25 meg - older 25Meg ATM used pair 2 & 3, same as Ethernet)

The (orange or green) reference is because TIA/EIA 568B uses green @ pair 2, TIA/EIA 568A uses the orange pair @ pair 2).

SO, the Pinout for 568A, (With the plug clip down/away from you) would be:
Green-White, Green, Orange-White, BLUE, BLUE_WHITE, Orange, Brown-white, Brown.

This would be the preferred Pinout under strict telephony conventions. The Blue pair (pair 1) is swapped (BLUE, BLUE-WHITE) compared to the other pair.

The Pinot for TIA/EIA 568B is the same except the orange & green pair are swapped (568A = orange pair 2, 568B = Green pair 2).

When using CAT5e, pair order is less critical for performance, since all pairs are qualified for high-speed data, but ordering your pair according to the EIA/TIA standards make it easier to remember "how you did it" six months later, and offers no frustration to the next person trying to use your cabling system. You have to do it from scratch, so you may as well do it "right" the first time. It takes no additional effort to do it right.

On a punch system, most often the white wire goes on the left side of the post ... just like in the connector. Most punch blocks now have an explicit color code label to indicate which color goes where .... follow that label.

Other rules you should be aware of if you're pulling the cable:

Keep the pulling tension under 15 pounds (it's different from one manufacturer's cable to another, but 15 is a safe value for all)

All bends (everywhere, no exceptions) should have a radius of NO LESS THAN 4 times the diameter of the cable ( 2" is usually quoted)

The maximum exposed (unjacketed) pair is 1/2" (one half inch, MAX)

The maximum length of untwisted pair for termination is 1/2" (less is much better - keep the twist up to the termination).

Make sure that, the exposed pair length and the untwisted pair length is the SAME half inch.

DO NOT (as in NEVER EVER) compress, crush, knot, twist, or kink the cable or jacket (don't cinch the cable ties tight).

The spec is for 90 Meters of SOLID cabling "in the wall" and 5 meters of stranded patch  at each end (100 meters total). This is not an absolute, but a good solid "rule of thumb". 

No matter how much cheaper you can buy it, NEVER NEVER NEVER run Stranded cabling in the walls. Stranded has a much higher loss than solid conductor UTP cabling.

Buy solid for the walls, stranded for patch cables.

Maximum run of CAT5 is "100 meters", however this rule does not apply to stranded cabling: stranded cabling cannot pass a signal for 100 meters ... it loses too much.

Be aware that there are basically four types of crimp-on plugs:

Flat (stranded or solid) and round (solid or stranded).

Make sure you have the right kind of plug for the cable you are crimping (usually "round" and "stranded" for a patch cable) it should be explicitly labeled as a "CAT5" (or Cat5e or Cat6). Cheap, unlabeled plugs may bring your cool new Cat5 / Cat5e / Cat6 cabling job down to "telephone grade" unrated cabling. The plugs for "flat" are for telephone use only -NEVER- use a "flat" plug for category-rated cabling.

(There are a bunch of others; these are the top of the list. Follow these rules and you're usually right in there for certified sweeps)
installing Network Cables.

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