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Unsure if this is the correct forum. Anyhow, we have had a network installed, using shielded cat 5 cable.

This cable is in the same trunking as the mains power cable.

The electrician says this is fine. The network man says its not.

Who is correct?


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migrated from Feb 1 '10 at 13:17

This question came from our site for professional and enthusiast programmers.

Graham, if you give us your locality, perhaps someone can comment on your local building/electrical code. – kmarsh Feb 1 '10 at 13:27
Are you SURE it's STP, not UTP? I've heard of STP, but never actually seen it! – Mark Henderson Feb 2 '10 at 20:58
In regard to whether or not this is the correct site (it's not really a forum), it's sort of on the edge. However, this is the kind of issue we all have to deal with at some stage or other. The fact that there have so far been no votes to close the question suggest that's how others are seeing it as well. – John Gardeniers Feb 3 '10 at 0:17

For safety, the electrician is correct.

For signal integrity, the network man is correct.

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Agree - check also local building regulations which may require power to be trunked seperately. – pjc50 Feb 1 '10 at 13:19
Safety, in this case, is usually about how many holes need to be made in the building code mandated "firewalls" that are usually required every X feet to keep a hypothetical fire under control. – Satanicpuppy Feb 1 '10 at 14:51
actually from a ssafety aspect this is probably unsafe electrically as I'd suspect that the cat 5 isn't properly bonded to ground so it's theoretically possible to build up enough inducted amps to arc over. – Jim B Feb 1 '10 at 15:40
Amps? Do you realize why Twisted Pair is, uh, twisted? – kmarsh Feb 1 '10 at 20:10
He's talking about the shield, not the pairs. – chris Feb 2 '10 at 20:41

As long as the cat-5 was properly shielded and bonded it should theoretically work (although it should have been prohibitively expensive). However this is not recommended pratice and I think doesn't pass tia-607. See "Installing Cat 5"

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+1 for the expensive part – Mark Henderson Feb 2 '10 at 20:58
I don't know what tia-607 is but let's remember that this is a global site and we have absolutely no idea where the OP is, let alone what standards or rules might apply at that location. – John Gardeniers Feb 3 '10 at 0:22
Tia is one of (if not THE) global standards org for telco matters. See generally if TIA said no thre is likely a building code that said no – Jim B Feb 3 '10 at 2:14

Your local authorities on these matters should always be consulted to see if there are rules covering this situation.

Back when I was an electrician the rules in my part of the world expressly forbade installing power and any kind of communications cable in the same conduit/duct. If placed in the same underground trench there had to be a minimum separation, but I don't recall what that distance was. The purpose was to try to eliminate the chance of mains power being fed into the comms cables in case someone did something stupid, like put a shovel into them. The Phone company (we only had one back then) had similar rules.

From the network side I would advise against it because shielded or not there is still a reasonable chance of inducing spikes into the cable. While that should never be damaging it can certainly affect throughput. The shield is supposed to prevent that from happening but cable shields are seldom completely effective.

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+1 - Althought I never did any of these installations myself I heard the same thing, over and over. – Mark Henderson Feb 2 '10 at 20:57

signal attenuation/interference - network man is correct. Electrician is wrong.

No network cable should be running alongside electric cables....

That is a cowboy job he did...

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