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AC_Hacker 02-12-17 08:24 PM

Need advice about Cat 6 running parallel to unshielded Romex...
Anybody have any code or experiential advice about running Cat 6 Ethernet parallel to unshielded Romex?

The parallel run will be about 16 ft.

I've seen a lot of opinion but little code on such a thing.

In one UK post, citing code said to keep the runs separated by at least 2".

An opinion said they should each be metal shielded and no less than 12".

Quite a bit of variation there.



DEnd 02-12-17 10:24 PM

Code is concerned with saftey, so there is a code issue with running Cat 6 parallel with Romex (as low voltage and high voltage cannot be run together, this is so that idiots who are messing in with wiring don't try to run 110v or 220v through low voltage wiring or equipment). Basically though they can run in the same wall but not through the same holes.

Best practice is to separate high voltage and Cat 6 by at least 12", use Electromagnetic shielded wiring, and limit parallel runs to less than 2'. That is not always possible though so if you need to get closer than 12" it should be a perpendicular run (at about a 90 angle) to the power line.

TobyB 03-09-17 01:00 PM

This is something we have some experience with at work-

from a safety standpoint, use different holes, as DEnd says.

From an induced current standpoint, your experience will vary depending
on a lot of factors, the first being how much current and how 'ugly' the AC load is.
If you're running a small alarm clock on the AC, the Cat5 will not care. If you're running
2 or 3 VFD's, it might be a problem.

The second big factor is how good the device using the Cat5 is. Good equipment
that makes proper use of the twisted pairs will be very immune to enough induced
current to cause problems. Equipment that does not take advantage of the noise
cancellation inherent in the wire will be a lot more susceptable.

So the real- world experience that we've had in temporary setups is that it's ALMOST
never a problem. Once in a blue moon we'll have to relocate a data line away from
a lighting dimmer feeder- but almost always, things that look ugly work fine.

Practically, in your shoes, I'd try to isolate the two as much as easily possible, and
not worry about it too much. If it's a typical home installation, you're just not
drawing enough current to cause problems. I WOULD use separate holes. I'm paranoid.

hope this helps,


Ormston 03-09-17 05:03 PM

2 Attachment(s)
UK regs (not that they apply) state 50mm, this is purely from a safety point of view and not interference.

The idea is that if the insulation on the Band 1 circuit (ethernet in your case) is not rated for Band 2 (mains voltage) then any damage to the mains cable could also bridge the undamaged Band 1 cables insulation and provide your router/pc with mains voltage.

From an interference point of view, ethernet is fairly tolerant. If possible 250-300mm should be adequate, failing that ftp (foil screened cable) grounded at 1 end or steel conduit again grounded at 1 end only will prevent any issues.

Also remember that to get the best possible throughput, the cat 6 should have no kinks or severe bends as it will be operating at rf frequencies and is more of a wave guide than a conductor.


Attachment 7655

Attachment 7656

TobyB 03-09-17 06:09 PM

That's a good idea to put it in conduit, if there's any worry.
It's certainly a very safe way to do it.

The thing about noise is that the twisting is 95% of the noise rejection,
at RF frequencies- any shielding or 'screening' is good for 5-9 dB, whereas
the twisting is in the 20-25 dB range. Which is REALLY counterintuitive,
but that's what the maths say, and our field experience really agrees with-
balanced twisted pairs very seldom have real RF noise issues, whereas unbalanced
signals are just antennas waiting to happen....


AC_Hacker 03-10-17 05:42 PM

Thanks or the replies!

You brought up issues that hadn't occurred to me.



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