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cat 5e crosstalk splitting pair to use 1 wire - 2 jacks

by biggdave5 / July 27, 2009 3:39 PM PDT

first off the question: While running a cat 5e wire for iptv can the pairs be split to be used for 2 jacks instead of one?

I know that to run ethernet only 2 pairs are used freeing up 2 pairs of wires

me (and many on my crew) being a cable/internet installers have used this handy trick many times but the boss has recently brought it to our attention he does not believe in this trick and fears crosstalk will cause iptv (pixeling/freezing) and internet connectivity related issues and thereby forbid wiring in this way until/if proof is shown that it is ok

and for anyone who wonders why not just run 2 wires we usually do this in apts where the cat5 is tucked under the baseboard and only 1 wire will fit loop to 1 tv then continue the loop to a 2nd or in cases where someone has a computer right next to their iptv 1 wire 1 run or finially in prebuilt homes where cat5 has been prewired to the 3rd story and the modem needs to be placed in the basement but the homeowner wants both internet and phone in a room (2 pair internet 1 pair phone) etc etc

So if anyone has any insight into why this trick is either a disaster waiting to happen or a perfectly safe shortcut of sorts it would be greatly appreciated

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Can't speak for iptv specifically but I do know that
by Steven Haninger / July 27, 2009 7:24 PM PDT
"I know that to run ethernet only 2 pairs are used freeing up 2 pairs of wires"

is not exactly true. The unused pairs in Ethernet cable serve a purpose. You cannot device the cable into two xmit/receive pairs, recode them and use them for two independent digital signals. An unused pair can be used for DC current POE but not another digital (and I presume analog) signal just by splitting the pairs. You don't even cut and splice Ethernet if the cable is too short for your purposes. There are strict standards even so far as how much untwisted length is permitted at terminations.
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That has been done.
by R. Proffitt Forum moderator / July 27, 2009 9:06 PM PDT

But far too many can't find "pairs." I must ask that everyone excuse me when I write if they can't find pairs then they are not going to get it to work.

Here's the usual article that you see ->

Now look at the replies. It looks like many can't make it work. I know it does work but how do would you tell a person nicely that they didn't get it right?

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thank you for the link and info
by biggdave5 / July 29, 2009 12:42 PM PDT
In reply to: That has been done.

I have shown this to my boss and he still believes it will not work even though that is precisly what we have been doing and even though most of the comments are from people having issues understanding they need to use "2" connections no more no less to make it work the comments made by those who touched on the basis of 10/100mbps vs 1000mbps where extremely helpfull ill keep working on the boss or maybe ill tell him the alternative would be to start using more ethernet/ac wall adapters

thanks again for the input

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That changes everything.
by R. Proffitt Forum moderator / July 29, 2009 12:47 PM PDT

Rule 1. The boss is always right.
Rule 2. When they're wrong read rule 1.

If they think it can't work then why not let it be and let them run the wires?

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catch 22
by biggdave5 / July 30, 2009 8:19 AM PDT

it becomes a catch 22 at times 1 wire can be tucked under a baseboard cant run 2 wires without stapling it to a wall or leaving as a trip hazard cant staple or leave a trip hazard because it doesnt look professional cant tell customer it cant be done and cant use a trick that makes it possible

can use an ethernet switch instead of splitting wires but then it becomes expencive and again cant turn job away if customer doesnt want to pay or it becomes a hit against myself

and my boss's actual words where "No on is to use split pairs until it is proven that it will work by someone with a engineering degree" so until i find someone with the qualifications the boss asks for ill just have to try to prove it to him with the research ive done online and the help ive recieved from yourself and others

As far as the boss is always right i have lucked into having a boss that will adapt to whats right if proven properly (even though it might be select individuals are allowed to use the trick and not everyone)

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