# 4 wire CAT 5..



## wildleg

the connection only requires 2 pr for a 100baseT connection, if I remember rightly.


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## TOOL_5150

wildleg said:


> the connection only requires 2 pr for a 100baseT connection, if I remember rightly.


This is true. You only need 4 pairs for POE or gigabit.

~Matt


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## JohnR

yeah on lan 10/100 you only (need) 4 wires or 2 pair. the other 4 wires are required for gigabit lan wiring or for POE <power over ethernet> I did a quick search for cat5 pinout 586B , and found this page which explains just what wires do what, http://www.ertyu.org/steven_nikkel/ethernetcables.html I have no affiliation to this site.

using just 4 wires can help if you only have 1 cable and a need to add a tel line or two or even another data drop at a location.HACK:whistling2: The drop will work but wont pass 1000baseT testing

Just remember that doing things this way is as you found out, NON standard and can leave the next guy hating you if you don't label what you did.


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## mikeh32

we used to do this when we didnt want to run another wire and they wanted 2 jacks. lol


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## Trimix-leccy

ethernet over Cat 5 only uses the orange and the green pairs.

do not know about elsewhere but in UK blue white pair is for analogue phones, orange white pair is for digital phone lines

brown pair not reall commonly used except in POE


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## MDShunk

I wired a small motel in 2004, and it was actually in the spec to do each room's jack plate with one cat5e cable. 2 pair for the internet in each room, and another pair for the phone in each room. Hey, who am I to argue? I support a customer's right to want something dumb.


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## danickstr

As mentioned, this is dumb, since even though it will usually work, it will occasionally mess up due to noise from the other appliance. I think the ringing phone, at 50 volts or whatever it is can impedance spike the data.


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## Electric_Light

The pairs can cross-talk through capacitive coupling and affect the adjacent pair. I remember when I had dial up and two lines. The two pairs were in same jacket. If second line was in use, the dial-up would only connect at 28,800bps instead of 54,800bps. This was duplicated every time.


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