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cat5 wires? 4 or 8?

C

CTho9305

Elite Member
I have 2 "cat5" cables (or so they are labelled), one with 4 wires, one with 8. what're they extra 4 for?
 
Only two sets of the twisted pairs are used in 10Base-T and 100Base-T. These are pins 1, 2, 3 and 6. The others are just extra.

I beleive 100Base-FX used all eight wires, but no one uses 100BaseFX
 
The "extra" wires are for things like PRI or T1 stuff. They share the same cable coding as say for a network. So just to be color compatible they follow the same rules.
 
Yep, 10/100 can run both 10 and 100Mbit. And for usual 10 or 100Base-T nework you only need 2 pairs of wires.
 
This is sort of like phone wiring. Only two wires of the four in a phone cord are actually used for data transmission.

Four wires of the eight are used in 10/100Mbps transmission over CAT5 cabling. I believe that gigabit Ethernet is supposed to use all eight wires of a CAT5e cable.

 
That's odd, I've never seen a CAT5 with only 4 wires in it before.
As CrashX said, for regular networking you only need 4 of the 8. CAT5 cables can be used for many things, for the common use of them in LANS you only need 4 of the wires...but still it's odd..most have 8.
 
At work, on the older patch panels that we have, I have come across numerous 4 wire cables. I replaced them all with standard 8wire. Back in the day cat5 cables were exspensive and to cut costs they ordered the 4 wire variety. Cheap bastards. 🙂
 
All of the cat5 i ran throughout my house i just used 2 pair. Much easier dealing with 4 wires instead of all 8 when it comes time to crimp the terminals.
 
There is a flavor of 10/100 that uses all four pairs....

REF 1
Subject: 11.0 Standard Networking Configurations

With reference to T568B above;
ATM 155Mbps uses pairs 2 and 4 (pins 1-2, 7-8)
Ethernet 10Base-T uses pairs 2 and 3 (pins 1-2, 3-6)
Ethernet 100Base-T4 uses pairs 2 and 3 (4T+) (pins 1-2, 3-6)
Ethernet 100Base-T8 uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)
Token-Ring uses pairs 1 and 3 (pins 4-5, 3-6)
TP-PMD uses pairs 2 and 4 (pins 1-2, 7-8)
100VG-AnyLAN uses pairs 1,2,3 and 4 (pins 4-5, 1-2, 3-6, 7-8)

REF 2
100Base-T4 Facts
Transmission Rate 100 Mb/s (full-duplex not supported)
Cable Type four pairs of Category 3 or better unshielded twisted pair (UTP) cabling,
100-ohm impedance rating
Maximum Segment Length 100 meters (328 feet)
Maximum Number of Transceivers per Segment 2
Connecter Technology RJ-45 style modular jack (8-pins)
Signal Encoding 8B6T

The two references I have dont agree with each other except that there is a 'flavor' that uses all four pairs.
 
CAT5 is a Standard; it is a Cable with 4 pairs of twisted wires (Solid or Strand).

Currently for regular Network communication, only two pairs (4 wires) are used.

TX+, TX-, RX+, RX-.

Some companies, who give free cables, at times save money and give you cable with only two pairs (my cable modem came with 6? of two pairs). These cables are not standard CAT5 cables.

The combination of the total 4 pairs has a shielding value, so it is not advisable to use non-standard cable.
 
Well, from what I understand.. CAT5 cables only actually use 4 wires out of the standard 8 for data transmission, you can use 1 CAT5 cable for a double wall-box outlet (that is what I do at work) for regular networking of PC's to the server (patch panel --> hub --> server)

It works rather well, it's not much of a true standard but it's efficient.. for a regular single connection i stick with the regular 568B standard.
 
In a cell site we ran cable from the CSU/DSX panel to a Network Terminal Box outside and we used heavy duty stuff that only had two pair. We also used a strange arrangement. Think it was white-Blue, blue then skipped a space then orange, white-orange.
 
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