Ethernet and dedicated radial

Would it be a faux pas to run a dedicated power twin & earth and ethernet cable in the same conduit ? Does the power cable affect ethernet as it would for a signal e.g. speaker cable ?

Best keep them apart if you can. Very short distances ie centimetres is ok, but not metres.

Thanks Robert. Unfortunately it would run from 1st to 3rd floor. I don’t have much choice so its time to decide if I run them together or dont bother with the ethernet… Would the problem be the power affecting ethernet data or the other way round ?

It’s the power affecting the Ethernet, and the possibility of signal attenuation. I think if you can get them just 5cm apart then it’s ok, but from what I can recall when I investigated the same for my install, running immediately in parallel in the same conduit pipe is not recommended.
Use shielded (S/ftp it’s called) if you can, where each pair is shielded, and then another shield for the whole thing.

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Yes it can to some extent, although the latest regs do allow for data & power to run together - within limits.
The power amperage in the run, the distance they run in close parallel & the distance between them all play a part as does using screened power and/or screened ethernet.
Separation is not normally required in domestic installations, however some separation can always be considered worthwhile & these are useful guidelines (taken from industrial regs) for 15m or longer runs.
Unscreened power cable and unscreened ethernet should have 20cm separation
Unscreened power cable and screened ethernet - 5cm
Screened power cable and unscreened ethernet - 2cm
Screened power cable and screened ethernet - 0cm


Thanks for the quick replies gents, exactly the feedback I was looking for.

It seems the sparky was already a step ahead of me and we will have separate conduits for data and power and both will be screened. 10mm T&E and Cat 6 STP. I get tripped up sometimes with technical terminology not in my native language !


I think it will depend on how clean your mains power is. If you have a lot of dirty SMPSs, household appliances etc. causing electrical noise then some of this might couple into your dedicated mains, and from there to the Ethernet cable. If this is the case, I wonder if a shielded Ethernet cable would be sensible (STP rather than UTP).
Possibly a better approach would be to use metal trunking instead of plastic for both mains and Ethernet, as I suspect this will provide better shielding than the braid and/or foil in the network cable.
When I ran network cables around the house I had no choice but to snake it around the consumer unit on its way to the HiFi, but as I was using fibre instead of copper Ethernet I didn’t worry about it.

As a more general approach, I believe prevention is better than cure, and I try to ensure that the house is free of noisy electrical devices as far as possible.

Yes, I came across figures like this when I was investigating getting main and ethernet to my astronomical observatory. Over long (30-50m) distances there appeared to safety concerns without sufficient separation.


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Thanks Chris. I meant STP not UTP, both the T&E and the Cat6 will be shielded. I corrected my post.

Ethernet will not be anywhere near the consumer unit.

We have a 3 phase supply so hopefully we can identify a quiet phase.

The sparky will have the final say on legal and/or safety requirements but if there is an option, should shields be grounded or not? Google hasn’t led me to a definitive answer so far.

Power screen should be earthed at one end, normally the power input end. It should not be connected at both ends as this makes it integral with the power earth (E). Think of it as a grounded conduit.
Ethernet is probably better not grounded as it can add noise if it finds another ground elsewhere, better with no ground than two.

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No not really, but the Ethernet cable can couple very low noise into the mains cable.
It is best to have some physical separation between the two cables, and that way there is likely to interfere with the balanced twisted pair properties of the cable…
if you need to bundle Ethernet cables together or any other cables over any length then best use screened Ethernet cables, and if you want to keep it simple, keep the grounding limited to one end, unless over a short distance.

If Ethernet cabling is being commercially undertaken for you, ask to have the fitter ensure the structured cabling complies with TIA 568. (Ethernet physical structured wiring standards) A typical sparkey is unlikely to be familiar, so better to use an appropriately qualified structured wiring professional if not doing yourself. Structured Ethernet wiring, like telephone wiring is quite a different discipline and profession from electrician wiring.
TIA 568 are the Ethernet cabling requirements for campus and commercial buildings. For domestic sites no standards are required but it is good practice.

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Just out of curiousity, what’s the real world issue?

I have unscreened Cat. 6 throughout the house. It’s mostly in it’s own conduit (but who knows what the in-wall separation between conduits is), but there’s a section where it hangs freely next to some XMVK, I guess separation will vary, and then passes through a narrow hole with it, where it’s pretty much squashed together, to then run parallel for say a meter or so before it enters the meter cupboard.

Now I can still maintain steady Gb speeds without issues, even over the longest of the cables (~ 25m + patch leads either end, so say ~28m). I don’t have the equipment to test 10Gbps. Does it simply mean that I would get 5-8Gbps max? Or is it likely it’s more of a theoretical problem, only if not parallel and unseparated for any significant length, say 50m?

The problem is noise coupling into the mains… it’s not about anything else.
The earth connections are about inadvertently creating inductive earth loops.
In commercial setups where there can be high concentrations of cables this is of more importance… in the home less so, but one is more likely to run in to people with OCD tendencies where these things could become ‘audible’

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I doubt running anything else together with electrical cables is ok from regulation point of view.

One of the XMVK cables is for the washer/dryer, the other is currently unused (we have a combined washer/dryer instead of individual appliances).

I guess I should re-run my tests while the washing is on :slight_smile:

Good for you it sounds like you have it covered… yes noise of course couples into your spur or radial and across consumer box if unfortunate… but the earth can pick up noise… and be potentially more susceptible if on PME supply… but a short run i can’t realistically see being a potential issue… and in the home less so… I would just bung it all together… I’m sure it will be fine.


Turns out I was mistaken again. The power cable will not be screened, the Cat6 will. The plan is to not ground the Cat6 screen at all.

Total length of power cable will be around 15m. Ethernet around 10m, of which 6m will run alongside the power cable, in separate (plastic) conduit.

Does this sound like a reasonable approach?

Yes, its reasonable, as they will be in separate conduits & as such will have some mm’s of separation even if its just the wall of both conduits. If your sparky can put a some separation distance between the conduits, so much the better
But you say the Cat6 will be screened, that means its Cat6a. Its OK not to ground it, the screen alone will still be OK. The BJC Cat6a for example has a screen but BJC make it so as the screen does not get a ground connection, its called a floating screen.

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Thanks Mike, sounds like we have a plan ! All going well, I hope to be setting up my system again in about 2 weeks…