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I have seen a few questions regarding how close ethernet cables can be to power cables without a significant impact on the data. For example:

Can I run CAT5/6 cables parallel to electrical cables?

Is "don't mix data and power cables" and "don't loop power cables" still valid nowadays?

It seems that the short answer is basically that they should be separated generously.

However in my case I will be running them in "separate conduits", which will be ordinary PEX tubing (underground). Furthermore, the power in this case will be a weak (high gauge) extension cord. The application is that I am running these cables to some security cameras which are 500-600ft distance away, and I don't think the cameras draw a lot of power. At least, it wouldn't be as much as present in the main line from the street.

The first question I linked has a comment which cites a standard:

800.133(A)(2) states that Communications wires and cables shall be separated by at least 50mm (2 in.) from conductors of any electrical light, power, Class 1 non-power-limited fire alarm or medium-power network-powered broadband communications circuits. Exceptions are if separate raceways or conduit are used for separating the communications cables/wires from the power conductors.

Does this mean, in my case I can just put them in different PEX tubes and not worry about how close they are- they can be right next to each other? There will be no loops, just a straight run (with a few curves).

It matters to me in this case because it would affect the width of the trench I am to dig.

I wonder if my question is more appropriate for some kind of electronics forum but I appreciate any guidance.

Thanks

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    The distance limitation for ethernet over CAT-5/6 is 100m (328 ft - you may be able to stretch it a bit longer, but not not 500 ft) so I think this is going to be a bigger limitation than running near power. Fiber to ethernet media converters aren't that expensive and you can easily find pre-terminated fiber in up to 1000 ft lengths, so I'd just run fiber for the network and then you don't need to worry about distance or interference. Especially since you're running power so you can power the media converter on the remote end,.
    – Johnny
    Mar 17, 2019 at 4:26
  • Ah, I see. I did assume I would be getting one of the media designations that is for long distance, but I didn't realize that these media types were necessarily fiber instead of copper. I'll check it out thanks. Edit: But now one thing I would worry about is how to terminate the fiber at the cameras. I suppose I can house termination equipment there as well.
    – user98368
    Mar 17, 2019 at 4:56
  • You can get 2-wire copper extenders, but if you have to use media converters anyway, but they tend to be slower and more expensive than fiber converters, and with fiber you eliminate the chance of electrical interference.
    – Johnny
    Mar 17, 2019 at 5:04
  • @Johnny a plow or spade interferes with both... :)
    – Solar Mike
    Mar 17, 2019 at 5:31

3 Answers 3

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You're not allowed to mix low-voltage and mains wiring in any way, shape or form in the same cables, conduits or raceways. The reason is safety: the data cables may not threaten the power cables, but melting or damage of the power cables absolutely could cross mains "hot" voltages onto your data cables.

This is only allowed if the data cables and everything the data cables connect to is also inside Class 1 wiring methods. Such as 24V latching-relay-based lighting controls. Or 0-10V dimming controls run in the same conduit as mains. Or ethernet used as SCADA between mains control equipment all mounted in Class 1 enclosures.

What's not allowed is running an ethernet through a mains conduit, having the ethernet land at an Ethernet cover plate, and then proceed via Ethernet cable which is decidedly not a class 1 wiring method to a local PC, where it enters a data port not hardened for mains power.

Anyway, as far as mains is concerned, "separate conduit and you're good". If your conduit is metal, you probably really are good. If it's plastic, then you might have signal interference if the signal is susceptible to 60Hz or whatever line noise is on the mains line; however the Electrical Code really doesn't care about that. These days most electronic signaling is so high frequency that it seems unlikely that old mains line noise could have much effect.

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I think the answer is "separate conduit, no problem at all" but I'll leave that for the code gurus.

But (a) you may be far better off with a Power-over-Ethernet solution if you can get cameras that will work that way as then you only have one set of cables (and one conduit) to worry about instead of 2 and (b) normal Ethernet is only rated to 328 feet - that is not simply a "signal quality isn't as good at long distance" problem (like with old RS232 serial cables) but a fundamental design issue that is not to be ignored.

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  • I think the issue with PoE as I have read is that it is also limited by distance, unless I have misunderstood.
    – user98368
    Mar 17, 2019 at 4:54
  • PoE is definitely also limited by distance. I am really raising two issues: 1 - PoE may help you avoid running a second cable (and a second conduit) and 2 - all normal Ethernet (10, 100, Gig.) is normally distance limited to 300 feet (actually 328 feet = 100 meters).
    – manassehkatz-Moving 2 Codidact
    Mar 17, 2019 at 5:21
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Router then Cat5e (can be twisted pair for short length) to High Power 4-Pair PoE Injector (60 watt) in structure, from there use Cat5e Solid Copper Burial Cable (not twisted conductor or non-solid copper) 100m max. to PoE Booster that is exterior all weather (couples lengths and boost power), then 100m max. Cat5e Solid Copper Burial to terminus (equipment).

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