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Is it ok to run multiple CAT3 [ADSL2+] and CAT6 cables next to each other, including within a wall, for a 20m - 30m run?

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    Here's an example of a professionally installed patch rack in a datacenter: i.redd.it/iv5u3feycyo51.jpg All datacenters look like that, including Stack Overflow's. The fact that you can post this question shows that there are no problems. – Jörg W Mittag Oct 4 '20 at 19:53
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    Interference from one cable to another is called alien crosstalk (AXT), and Ethernet is specifically designed to withstand considerable amount of AXT. Also, CAT cables must be in compliance with stringent performance requirements. A lot of engineering efforts have spent to address these issues, for example, see Effects of alien crosstalk on the physical layer (note the article was historical, written in 2000). – 比尔盖子 Oct 5 '20 at 6:38
  • Just don't wrap cables around one another, ensure they are parallell to one another until they diverge. – keag Oct 5 '20 at 15:11
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    Just be sure to keep the CAT cables and DOG cables away from each other. – Daniel R Hicks Oct 5 '20 at 18:31
  • @JörgWMittag I dunno... Stack Overflow's network wiring probably looks something like this – S.S. Anne Oct 5 '20 at 20:51
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Yes, as each cable has twisted pairs to prevent EMF interference, with each twisted pair's twist being a different length than the others.

  • Ethernet and phone cables operate at low voltage and amperage; the only thing to avoid would be placing them next to AC power cables.
    • While it's unlikely running a bundle next to a few AC power cables would negatively affect the data being transmitted, it's best practice to run AC power cables separately from low voltage data lines, whether they be audio, video, or ethernet/phone lines, and if low voltage data lines must intersect AC power cables, it's best practice to do so at right angles to prevent EMF interference.

When running through walls, ensure cabling is:

  • CMP rated, as CMP cable jackets are fire-resistant
    • U.S. NEC requires CMP jackets for any data cables run within an enclosed plenum cavity as they smolder out quickly upon catching fire
  • Not run within the same space as electrical wiring, else EMF interference is a real possibility
    • U.S. NEC requires this as well IIRC
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    +1, though I'd say the main reason to avoid running data + power in the same bundle is so someone doesn't drill / hammer through the whole lot, sending mains voltage down your data lines. Brings a new meaning to PoE... :-) – berry120 Oct 5 '20 at 9:29
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    for CMP rating, that is not necessary if run through a wall with insulation, CMR is fine, as there is no flowing source of fresh oxygen – Richie Frame Oct 6 '20 at 1:20
  • @RichieFrame I thought about specifying CMR as well, but since CMP isn't more expensive and is often the only option for other low voltage data cables (they're often run in the same wall cavity by homeowners), I didn't want to over-complicate by explaining the difference of Riser and Plenum cable jackets. I do see a potential issue with my NEC wording though and have edited accordingly. – JW0914 Oct 6 '20 at 3:25
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Yes, of course. In datacenters, we have bundles of dozens and dozens of cacat5/cat6 running together.

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    There's something deeply profound about reading that as "caca cabling" – Criggie Oct 5 '20 at 23:54
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    That made me laugh out loud! – Mark Scheck Oct 6 '20 at 9:04
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Yes, this is fine.

What you should not do is run network cable directly adjacent to power cabling. I generally try follow what I like to call the "Rule of 6": if power and data lines will run alongside each other for 6 feet or more, they should be at least 6 inches apart — though circumstances don't always allow this.

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