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Use of abandoned phone wiring for Ethernet connections

by sailor1120 / December 27, 2012 2:07 AM PST

I would like to extend my ethernet network to my shop which is located approximately 400 feet from my house. Burying new cable would be difficult due to paved driveways and other obstructions but I have an existing unused phone line buried to the shop. This is (presumably) a high quality cable installed by the phone company to provide service to my home and is no longer used so I am wondering if I can convert it to use as a network cable? I believe the cable has 6 pairs. My intention would be to install an access point in the shop to provide wifi for my smartphone and laptop.

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All Answers

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Try it.
by R. Proffitt Forum moderator / December 27, 2012 2:32 AM PST

It's never supportable as it is what it is. What's stopping you?

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I believe 100 meters is supposed to be max
by wpgwpg / December 27, 2012 3:20 AM PST

If I'm right and 100 meters is the max, you'd be over on that aspect for starters. Every foot of distance adds a nanosecond to delay time; that may or might not be much of a problem. An extra 100 feet would be .1 milliseconds which wouldn't seem like that big a deal, but then I'm no expert. Then there's the shielding to consider. Usually phone wires aren't shielded, so you could have a noise and crosstalk problem I'd think. Best case you wouldn't get anywhere near gigabit rates. With 6 pair of wires you're OK on that count, but you'd need to be absolutely sure you got them matched up correctly. Hopefully the colors would be distinct enough so that wouldn't be a problem. It certainly wouldn't be that expensive to get a couple of connector plugs and a crimping tool to give it a try it. If you do, set the transfer rate to 10 mbps to start and see if you could get that to work. Obviously you'd be on your own with this experiment, but it certainly would be the cheapest alternative.
If you do try it, I for one would be most interested to hear the results.

Good luck.

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Whoops, make that .1 MICROseconds
by wpgwpg / December 27, 2012 3:23 AM PST

I said milliseconds, but should've said microseconds. That makes the extra distance 1000 times less likely to be a problem, but again I'm no expert. Plain

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VDSL Ethernet Extender
by sunwatcher / December 27, 2012 1:10 PM PST

There's no reason why you can't give it a try. Fairly easy and inexpensive to add a couple of RJ45 jacks to the end of the cable. Be aware that you would be exceeding the design limitations of distance for Ethernet, so I wouldn't expect this to work well, if at all.

If this is important and you don't mind spending some money, a very good solution is this VDSL ethernet extender kit. The kit requires only a single pair of wires.

There are HomePNA solutions for phoneline but they are much more difficult to find.

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Use of abandoned phone wiring for Ethernet connections
by sailor1120 / December 28, 2012 3:25 AM PST

Thanks for all of the replies! I have since learned that the cable in question is just a four conductor cable instead of my original thought that it was 6 pairs. In any event, I am encouraged that no one raised any significant technical reasons why it won't work and I will give it a try. Knowing about the VDSL extender kit gives me confidence that a solution is available at a reasonable price even if it turns out I can't simply hook up to the wires.

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If I can jump in here . . .
by Coryphaeus / December 28, 2012 10:48 PM PST

It may work but your speed will drop significantly. Reason being is the number of twists per foot of each pair. Ethernet cable has more twists to keep down self induction and mutual induction of the pairs of wires. Telephone wire only carries low frequency signals and do not need many twists. High speed data has what is called "apparent frequency" which is in the mega-Hertz range. The higher the frequency the more twists are needed to combat induction which causes signal loss and therefore data speed drop.

Give it a shot. It'll either work or it won't.

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Thanks W!
by R. Proffitt Forum moderator / December 29, 2012 3:14 AM PST

I forget something VERY IMPORTANT. I've run into non-twisted wiring like this and that is NOT TO BE USED AT ALL. The reason for the twists is to reduce, well, that voltage induced onto the wires from say a nearby lightning storm. Flat untwisted wires are an antenna and years ago we had too much fun watching the sparks fly from just a 100 foot run.


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Actually . . .
by Coryphaeus / December 29, 2012 6:03 AM PST
In reply to: Thanks W!

the twists are more for self induction. As the frequency (and amplitude) rises and falls, the magnetic field rises and falls, and has a tendency to cancel out the rise and fall of said magnetic field which will, in direct proportion, affect the frequency response of the wiring. More twists per foot have the affect of keeping the induced magnetic field more contained to a single conductor and not affecting the other conductor of the pair (mutual induction). Capacitance is also a factor, especially in high apparent frequency circuits.


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What obstruction is between your house and shop?
by esotericbyte / December 31, 2012 2:33 AM PST

I am of course interested in the detailed technical reasons why pots lines are not good for data transmission and conversely why ethernet cables are engineered the way they are but this is not going to get your phone and laptop to work. It is a trip down the rabbit hole. I suggest that you work around this old phone line. As it turns out voice communications are low bandwidth (11khz sample rate equivalent) and POTS lines are not over-engineered.

What strikes me about your needs as reported is that you are not looking to eliminate wireless latency. You are planning to use an AP on the other end. There could be good uses for an ethernet connection in your workshop but if you are planning to use Wifi anyway I'd try an AP in a second floor or attic window for example. I'd go with N-300 capable N-600's are priced too high imho.If you don't get good coverage over the whole shop but do in a window or corner you could add another access point there as a bridge or extender. I prefer to use APs with WDS (wireless distribution system). This allows them to be paired together to work as a network both bridging and extending service wirelessly. This will allow the connections to be seamless from your home and workshop.
Finally, I've found power line adapters surprisingly easy and fast. I am pretty sure mine are working over breakers and a breakout box. Just don't put in any sort of power cleaning or surge protection between them. I am also not sure what interference your shop equipment may create. I'd position it away from any motors.


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Distance is the main obstruction
by sailor1120 / December 31, 2012 6:55 AM PST

I actually have two locations with buried phone lines that I would like to connect to my network--one is approximately 300 feet in one direction from the house and the other is approximately 450 feet in the opposite direction. As I understand wifi (not particularly well) that pretty well exceeds the maximum reach of the signal so I hope to be able to install access points at both remote locations linked by a wired connection. This would provide pretty good coverage throughout my property including areas (pool) where the grandkids like to hang out and stay connected. I was contemplating trying the power line devices and then remembered that I actually have the buried phone cables so it's a question of which approach makes the most sense? If I can just wire the phone lines into my network then I assume that would be the simplest solution. The power line adapters represent an additional cost but, in my opinion, would be worth it if they do the job. I would also consider the VDSL ethernet extender mentioned previously if that is a better solution.

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