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tojoski

Need advice to correct bone-headed cabling mistake.

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tojoski

I could use some advice guys.

 

I've been building / having built a workshop about 175 feet behind my house. Here's the problem that I didn't realize (duh) until it was too late....

 

I ran the cat6 cable in the same trench as the AC for about 120 feet! The cat6 is in a 3/4" pvc pipe, and the AC is 2/0-2/0-2/0-1/0 in a 2.5" conduit.

 

Now I'm starting to wonder if the close proximity will cause some of the AC to bleed over into the cat6 like a transformer. I know its a no-no to run them together but I think my my mind was in another place the day I rented the trencher. I can't find any information anywhere where it has actually caused an issue in practice.

 

So the way I see it I have a couple of options:

 

1) Use it like it is and hope for the best... although it seems to me the more active the AC or the more load on it the more voltage that could be transferred. I would have to put a 240V load on it at close to 100A to know for sure

 

2) Rent the trencher again and move the cat6 over a few feet leaving only about 4 feet at the end where they are close. about $200

 

3) Use the cat6 to pull a fiber... frankly I'm not sure if this is even possible..the 3/4" pvc has several 45 and 90deg fittings.. also I've never

used fiber or terminated connections.

 

Wireless is not really a good option, as I want to have an IP Phone out there eventually.

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ikon

Is the AC conduit metal, as in EMT? If so, then I think you are good to go. Because it's buried, the conduit should be grounded, which should also sink any inductive signals. I would give it a try. Do some file copy tests, using files of all different sizes.

 

I'm not aware of any data that supports the idea that a more heavily used AC line is more inductive. If you find any, please post about it.

 

BTW, from a technical standpoint, wireless actually could be an option, but I'm sure the cost would be higher than you want.

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tojoski

Both are in PVC

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ikon

Is it covered over yet? If not, and you're really concerned, you could wrap some aluminum foil around the CAT6 conduit. But, I would test it before doing anything.

 

The whole point of UTP is that it accepts inducted signals and filters them out at each end. That's why it's twisted. The idea is that inducted signals get picked up equally by both wires in a twisted pair. At each end, filters remove, or leave behind, any signal that's equal in both wires.

 

I have seen tests where 100baseT cables were run beside AC cables, wrapped around fluorescent fixtures, and then wapped around a large electric motor. The signal coming out of the switch at the end was virtually perfect.

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cskenney

Transformers (which is what you are describing) have many windings in order to produce a current in the secondary conductor. I don't think you have to be concerned about the transformer effect. In fact, the larger issue (in my opinion) is coupling electrical line noise into your ethernet cable. This is the primary reason you don't run AC and communication lines in parallel. The wires will act line antenna and when oriented in the same plane (direction) the can create a mutual coupling. Now any noise you have in the AC line (from things like the fridge running or an AC welder) can actually end up coupled as interference on the ethernet wiring. To combat this the ethernet cable used twisted pairs (wires are not simply straight).

 

So in my opinion the big question is will this arrangement significantly slow down my network connection because of the AC noise that might be present.

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ikon

When I say 'inducted signals' I'm being inclusive: inducted current and noise. As you intimated, the point of the twists is to permit the system to filter out the erroneous signals, whatever their source. That's why the test we ran years ago included the fluorescent lights; they're notorious for 'sparky', erratic, noise-producing signals.

 

A lot of the results will depend on how good the switches are. If they're good ones they will be able to adequately filter the noise. If not, well......

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cskenney

Bottom line is I would use it like it is for a while.

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ikon

Agreed. Try it out. Copy a bunch of files, both ways; get the measure of it before deciding it's broke :)

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tojoski

Thanks for the input.. no the trench isn't covered yet.

 

I don't mind loosing a little bandwidth, the link will be a gigabit, and mainly it will be used for internet access, maybe the occasional file transfer but nothing large.

 

I was mainly concerned about the transformer effect.

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ikon

Sounds like the aluminum foil might be a good idea then. It wouldn't take much to do it, and it wouldn't cost much either. Also, if you tie one end of the foil to your house's ground spike, it could help to alleviate lightning ground strikes from taking out your siwtching gear.

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