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Running Cable

By mowen ·
I have run across a little problem and was wondering if anyone had info for me. I know what the problem and solution are I just need some distancing or shielding info.

I have 2 star LANs and an uplink between them. The problem is the cable for the uplink between the 2 hubs is running parallel to a 220-power line.

What I need to know is how far away from 220 to run the cable or if anyone knows what kind of piping would be good to use for best shielding standards.

Any info would be greatly appreciated.

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Running Cable

by rkelly In reply to Running Cable

In answer to your question, the electromagnetic shielding used in STP (shielded twisted pair) should be more than adequate for your needs. Just try to make sure that the stp does not actually come in contact with the mains cables.

The only thing that you haven't mentioned are the distances involved - assume that the segment lenght for stp is the same as utp and you cannot go too far wrong. If you have lenghts longer than 100 m you will need to look at alternative technologies - fddi etc.

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Running Cable

by mowen In reply to Running Cable

Not what I asked

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Running Cable

by Barry Hensley In reply to Running Cable

I have to assume that you are connecting 2 ethernet segments over 10BaseT or 100Base-TX.

In this case, theoretically you don't need to do anything. If you have the Cat5 cables properly terminated, 60Hz A/C circuits won't adversely affect them. However, you will find lots of information that suggests that you should guard against the possible interference. In this case, use STP instead of UTP. STP has a shield that can be connected to a grounded source on either end, effectively keeping interference away from the internal conductors. If you choose to use STP, be sure to ground the shield on either end so that it works properly.

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Running Cable

by mowen In reply to Running Cable

Not what I asked

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Running Cable

by mowen In reply to Running Cable

Using Cat5 UTP at about 280 feet outdoors through a pcv pipe about 18 inches from 220-line at 100mbps ethernet with a repeater attached somewhere in the middle. It parallels it for about 30 feet. They are running a lot of welding equipment.

About every 50 to 100 feet I have a junction box. I ran the cable to each one and tested until it crashed and it crashed when I ran it parallel to 220s.

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Running Cable

by McKayTech In reply to Running Cable

First of all, if they are running welders, the problem probably isn't the 220v of nominal current but the huge inductive spikes that welding equipment can cause.

But a couple of questions arise in my mind:
What is the 220 running through? If it's not running through EMT conduit, I think I would start with that (if it's feasible). If the 220 is within a properly grounded metallic jacket, 18 inches should be enough.
On the other hand, you could shield the data cable, either by using STP orenclosing the data cable within conduit. For a long outdoor run, I think I might consider that for other reasons as well (those vicious rodents...).

However, I've had a couple of these situations where the only feasible answer turned out to be fiber, but mainly because there was a significant difference in ground potential between the two sites.

paul

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Running Cable

by mowen In reply to Running Cable

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Running Cable

by mowen In reply to Running Cable

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