Network cable running parallel to electrical cable

marky1124

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Hi,

I am looking for some realistic advice please.

I need to run some electrical and network cable through an outside conduit from my house to my shed along a distance of about 20 meters. The conduit will be buried a couple of feet underground.

The electrical cable will be standard household stuff. I'm in the UK so 240V and perhaps up to 15A? (I'm not an electrician)

I know that running network cable parallel to electrical cable is 'a bad idea', but I'm looking to understand 'how bad'. I'm not looking for the fastest speeds just decent reliable connectivity, for instance currently the networking gear I have is 100Mbps and no doubt at some point it'll all be 1000Mbps.

So I presume I'm looking at either shielded cat5e or shielded cat6 network cable in a 4" (200mm) conduit running parallel with the electrical cable for about 20 meters. Perhaps there's such thing as shielded electrical cable too?

Anyway I'd be happy if my 100Mbps kit would work <5ms response and without packet drops at say 30Mbps. Likewise if/when my kit is 1000Mbps if it obtained 300Mbps that'd be fine. I don't mind sacrificing some speed but I don't want an unreliable network.

So is that realistic? Or would running network cable next to electrical cable create a worse situation than that?

Ideally I'd like to find some reports or evidence of people that have tried this and know how it works out in practice.

Thanks very much in advance for your advice,
Cheers,
Mark
 

Eximo

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For that distance I would certainly recommend CAT6e cable, and since you are burying it, might as well put the best down there.

CAT5e would be unshielded twisted pair.
CAT6e would be sheilded twisted pair, so another layer of protection (and under ideal conditions 10Gbps).

Neat thing is that as long as your power cable has the positive and neutral wires side by side, the magnetic field they can generate is basically canceled out. Any twisting adds to this effect, as well as preventing long runs from acting as antennae.

If you really want to spend some cash you can look into fiber(optical)network cabling.
 

everlost

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you can get sheilded cat5 cable. but i would still run cat6, it is designed to handle interferance better, and it would save you from redoing this run again in the future. make sure its shielded, and you terminate the sheild poperly. a sheilded port and plug look like they have metal armor on them.

you would ground ONLY ONE END of the cable, preferably the side closest to the utility panel that feeds your computer equipment. the other end of your cable can be terminated with a normal cat6 plug.
 

dbhosttexas

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If you are digging a trench to run conduit for buried cable, I would recommend that you go ahead and dig the trench deep enogh to run 2 conduits, separated at least 6" apart. Running data cable in a conduit shared with power is a sure way to saturate the cable with electromagnetic interference. And although I have not done in personally, I have had to remove ethernet cable that was run in a manner you speak, and run new cable far enough away to avoid the interference problems. In the cases I have worked, the data cable simply becomes too unstable to be usable...

You might be able to get away with shielded category 6 cable, but why risk it?
 

Beachnative

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SPOT ON dbhosttexas, running a cat 5 or 6 in a conduit with high voltage is a disaster waiting to happen. Under no circumstances would this be accepted in the US, none!

Safety should be your main concern then performance. EMI over a distance will induce noise and performance will be affected.

Try running a piece of network Cat5 next to a long run of existing nonshielded conduit and use a wire toner to listen to the noise induced by EMI. Your performance selections on your nics are base 10....10/100/1000. What could happen is if you set the duplex speed to auto it will try to run at 1000 speed then try 100 then 10. until ti stays at a stable rate. You cannot expect it to run at 300M, the auto feature runs at base 10>1, 10>3, 10>3 only. and I'll bet if you did leave it at auto it would still fail as the noise variation changes making it cycle between the three selections and you would be forced to manually select what would work.........I know I've had to do this to get a network to work because I used 35 year old phone lines for a 100 foot run due to budgetary constraints.

DO NOT UNDER ANY CIRCUMSTANCES RUN A NETWORK CABLE IN WITH A/C VOLTAGE!!!!
 

marky1124

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Thank you for your responses. There's a bit of a mixed opinion.

Eximo you seem to be suggesting that with the right electrical cable I'll be fine, and everlost thank you about the grounding tips.

dbhosttexas I take your point about running two conduits at different heights. I believe the landscaper was going to bury the conduit 24" down. I was mainly looking to avoid digging two trenches but having a two conduits at different heights is a distinct possibility. I see that Siemons have made recommendations here: http://www.siemon.co.uk/uk/white_papers/02-03-22-emi.asp. Perhaps I could have one conduit at 24" and another at 18".

Thanks beachnative for your warnings. I understand what you are saying about negotiation. Is 240V considered High Voltage, I thought wasn't.

Cheers,
Mark
 
Part of what db is saying is related to USA building codes. You are not allowed to run the ethernet cable in the same electrical conduit at all. There may be some that is allowed but it is related to safety not interference. As deep as you are going I would just buy direct bury ethernet cable and not spend the money for a second conduit...or use something like cheap drip irrigation tubing just to keep your ethernet dry. The conduit for the electrical cable (especially if it has metal) will block a lot of he interference. A couple inches of dirt will likely do the rest. I would (unless building code prevents it) put the electrical in bury it some what and then lay the ethernet in the same trench. There are code requirements in the USA for how much spacing you must have between the conduit and other stuff in the same trench even.
 

dbhosttexas

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Actually I was suggesting since you will have the trencher there, or guys with shovels digging the trench, to just dig it wider. Once the initial trench is dug going wider is very little extra labor. Make sure you have at least 6" separation between the conduits, and you should be good to go. And yes safety is one of the issues and reasons behind code, and I was referencing the building code for the U.S., particularly that which applies to my region, which is the Gulf of Mexico. I have to deal not only with expansive clay soils, but LOTS of salt in the environment...

I get the impression from your writing style that perhaps you might be in the U.K. however. So standards could be quite different. I would check with whatever authority you have that regulates building / construction. What you are wanting to do will require a permit I am sure, and I suspect your regulations would actually be a bit stricter than mine... Even if not, if you are in the U.S., or even Texas, if you are in a different municipality than I am, then chances are there are some areas your authority varies from the national building and electrical codes, and you will need to make sure you are doing things they way your regulating authority wants them done. I would hate for you to have to rip it all back out and re do it to keep red tape worms happy...
 

Beachnative

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"The National Electric Code (NEC) sets the required burial depth of electric wire in rigid, nonmetallic conduit, such as PVC, at 18 inches. Cable in any conduit, including PVC, that is buried at this depth is not in danger of being severed or disturbed by normal digging. However, keep in mind that no cable or conduit is protected from digging by construction equipment such as trench diggers or backhoes."

Read more: http://www.doityourself.com/stry/calculating-how-deep-to-bury-outdoor-electrical-wire#ixzz2Xokfw2Sy
 

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