There is a boardwalk through a wooded marsh approximately 250ft long with no line of sight between the ends. Along one side of that boardwalk is an electrical circuit. I need to establish an Ethernet connection between both ends of said boardwalk to transmit video feeds.

If I were to run an Ethernet cable on the opposite side of the boardwalk, might there be appreciable interference from the 120v 60 Hz AC circuit running in parallel for that 250ft with approximately 3ft of separation?

Would Cat 5e vs Cat 6 make much difference?

  • Is the circuit run using UF, some type of MC, or in metal or nonmetallic conduit? Commented Oct 23, 2016 at 15:34
  • The electric wire is in metal conduit.
    – CragMonkey
    Commented Oct 23, 2016 at 15:43
  • 2
    On the opposite side there would be no interference. I see cat 5 run very close to 120-480v circuits in wireways only separated by a thin insulator wall. Cat 6 will provide for higher bandwidth but costs more. Where I need higher bandwidth or longer distances I switch to fiber optic and add network interface cards for slightly more than cat 6.
    – Ed Beal
    Commented Oct 23, 2016 at 15:48
  • 1
    If you run fiber optic, and it's non-conductive and legal for running in AC power conduit, just do that! Commented Oct 23, 2016 at 17:34

2 Answers 2


Since the electrical wire is in metal conduit, I would have no fear of interference. Just do not attach the ethernet to the metal conduit, as you are not allowed to use electrical conduit as a hanger for anything.

Another factor: Most plastics do not like UV light, which the sun emits in great quantity. This could be a serious problem for the sheath on your ethernet cable, depending on placement. Cable rated for outdoors or for UV exposure will last longer, but will still fail in direct sunlight.

(I think, due to your concerns about interference, you wouldn't think to put the ethernet inside conduit carrying 120/240/480V power cables. But just for reference, that is not allowed unless you use transformers to step down the AC voltage significantly, which would not work unless your loads were quite small.)

  • 1
    My intention is to attach the outdoor rated cable on the opposite side of the boardwalk from the conduit, and the whole walkway is in heavy shade all day so UV exposure will be minimal.
    – CragMonkey
    Commented Oct 23, 2016 at 17:29
  • 1
    That should be fine, but watch out for UV deterioration nonetheless. It's surprisingly insidious. Commented Oct 24, 2016 at 0:07
  • 1
    Appreciate the warning. I'll be sure to get cable with a UV-resitant jacket.
    – CragMonkey
    Commented Oct 24, 2016 at 0:12

For that distance, I'd recommend using shielded CAT-6A cable. We have a similar issue in our church, and over only 150ft we found that standard cat-6 cable lost enough quality that it was noticeable. No problems with shielded CAT-6A (which is designed for 10Gb/s to a maximum of 328ft)

3ft of separation from 120v is plenty for any implementation; I'm usually happy with 6 inches, as long as there are no cable crossings.

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