Apologies if this isn't the right place for this question.

I'm converting an out-building to a home office. The structure is approximately 175 feet from the house. We're digging a trench for a 240V power line, and I'm planning to include a network cable so I can get a fast connection back to the rack in the house.

Is CAT-5e suitable for this? Typically, one wouldn't run a signal cable next to a power cable. Over 175 feet, I imagine that the interference / crosstalk would be significant.

I'm also considering running single-mode fiber. The cable prices are reasonable, and there's no real opportunity for (significant) interference from the power line.

Suggestions? I assume this is a solved problem, but my Google kung-fu is failing me.

I've seen gadgets that will let you send network traffic over the power lines, but have no personal experience re:reliability or performance.

I'm coming up short on tags for this post.

  • fiber would be best, but cat5e will likely do just fine for many years to come. Run each service in it's own metalized conduit. (local building code may already require this.)
    – Ricky
    Jun 4, 2016 at 21:27
  • @RickyBeam The codes allow direct burial in this context, and the shape of the trench (zig-zags a lot) is going to make a metal conduit pretty interesting. And then there's the cool factor... :/ I regularly have to move large files (2-6GB) around. If I wind up with something that's only delivering ~100Mb, I'll spend a lot of time playing angry birds.
    – 3Dave
    Jun 4, 2016 at 21:30
  • 1G is the most you are likely to ever move on copper. (yes, there are 10G products but at insane prices) If you want to do 10G then you'll cat6a or, better just go with fiber. And metal conduit doesn't mean rigid pipe.
    – Ricky
    Jun 4, 2016 at 21:34
  • 1
    I, too, am in Dallas. There is a lot of liability associated with OSP cabling. Lightning will travel great distances through the ground. The conduit or armor is a great conductor. Improperly grounded OSP cabling is illegal in the U.S, and you must follow the NEC. You need to bury it properly. As you must be aware, the soil in Texas moves (swells a lot when wet, and shrinks a lot during droughts, it's why basements are so rare, and why there are so many foundation problems in Texas), and you will eventually end up with broken cable if it isn't done properly.
    – Ron Maupin
    Jun 5, 2016 at 2:27
  • 1
    No need to invest in SM fiber - MM should generally be cheaper and a couple hundred feet is well within its range. Jun 5, 2016 at 17:46

3 Answers 3


In my personal experience "interference from power lines" is more of a marketing myth than reality with twisted pair cable, which is actually highly resistant to interference pickup, by design.

But fiber its the right choice 10 times out of 10.

Main advantage (practical) - complete electrical isolation - no lovely lighting-induced surges on the data lines frying equipment. Having had those, I strongly prefer fiber for ANY outside line, no matter how short. It's also immune to probably mythical powerline interference, if that makes you happy.

Single mode fiber offers you the highest possible bandwidth now and in the future, and is relatively inexpensive. If you can get "RBR" (reduced bend radius) fiber for an upcharge that you'd consider small, I recommend that, too. Otherwise, just be careful about bend radius when installing the fiber. The "Wisdom" of multimode fiber for short links is based on cost arguments that are no longer true, in my experience, and it will become obsolete where the single-mode won't.

The cost of multimode fiber suitable for high bandwidth so greatly exceeds the cost of singlemode equipment at the ends of the fiber that it makes no sense. If you shop used equipment, the prices get even better. (I have a campus covered with mostly short links of SM fiber circa 2010, because I did the math on this and also read the writing on the wall. If you had installed SM and MM fibers in 1980, your SM fiber would still be good, and your MM fiber would have been obsoleted 3-4 times already.)

  • About 35% more for SM .vs. MM when I shopped new ones for the budgeting phase, which still made the SM cheaper since cable cost (~100% more for OM3) exceeded that by a significant amount. In actual purchasing, used SM 4 GB "fiberchannel" SFPs were found to be compatible with our 1GB ethernet switches at a cost of ~$5 each. 10 GB stuff will have to wait for the price to come down before our school can afford it...but the fiber will support it, or whatever comes next.
    – Ecnerwal
    Jun 8, 2016 at 3:39
  • Fibrechannel is typically for communication between SANs and servers...it's a different protocol from ethernet. Jun 9, 2016 at 0:38
  • No Duh. However, I've tested and used at least 3 different FC SFPs that are quite happy to run ethernet (it's even in the spec sheet) - just depends what box you plug them into - a FC box or an ethernet box. The box deals with the protocol, the SFP deals with the data it's handed by the box. If your vendor is an epithet you may be restricted to overpriced vendor-specific SFPs, but that just means your vendor is an epithet and you shouldn't have bought their overpriced alternate-epithet in the first place - or you signed up to be yet-another-epithet-ed by them when you did.
    – Ecnerwal
    Jun 9, 2016 at 1:17
  • That's fine, I'm glad you know the difference, but my comment isn't for you. It's for people who don't know the diff. They should know that ethernet and fibrechannel are two different protocols, shouldn't they? Jun 9, 2016 at 2:18

I can think of at least a few reasons for using fiber:

  • Higher bandwidth
  • Zero interference from power lines
  • It is much better to invest now in a fast medium than getting satisfied of a copper cable and then having to redo all the work again in a few years, when you'll want to upgrade

In most home network, cat5e is always chosen as the medium for gigabit speeds or if you want 10Gbit/s links, then CAT6 is a good choice once the distance is no so long. Certainly, for bandwidth enjoyment in future, single-mode fiber or multi-mode fiber are all okay. By the way, what's your budget?

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