Cable separation - Power Network Coax

[dhutch]

In the middle of a whole house re-wire.

Electrican is in charge of power and lighting, however we will also have some network cable to core locations (WiFi AP, Router, Office, TV point etc) and Coax to a few places (TV and FM) and want to check cable separation requirements.

Obviously running network and power parallel for any reasonable length is out. Can I run them together for 1ft into first floor and high level boxes? Or for 6ft down to ground floor boxes?

Can I run network cables and TV/FM coax together?
We don't watch much live tv but plan to have ability to use freeview.

There will also be conventional speaker points from a central amp rack, for which I plan to run T&E for speaker feed and a network cable. T&E is cheap and effective for speakers, and for future proofing you can always wire it to power and convert to a sonos type system.

Network will be cat6 UTP as far as I know.


Thanks

Daniel

[crmcatee]

They are supposed to have 30cm separation if running parallel. It's not much work to channel out a separate drop or climb to keep the separation.

No problem running coax/network stuff together.

[megaphone]

Don't fuss about it too much, as you say, don't run CAT6 with power over longer distances than really necessary, try and keep a gap where you can.

Co-ax and CATx can be run together no probs. Check co-ax cable is proper WF100, this has a copper shield/screen, it's a bit more expensive than bog standard RG6, but worth it.

http://www.webro.com/coaxial/tv-satellite/wf100-ca...

[dhutch]

Ok, so worth running separate chase 6ft down for network cables to office etc, long drops and plain walls, not that hard as said.

Obviously will then route atleast 300mm apart when between floors and down to patch panel.

For the speaker drops, can probably neck the t&e and network together for the 1ft drop down, which will save a second set of holes behind the plaster moulding work. Don't even have plans to use the network as yet so reasonable compromise.

Coax and network can run together to TV/FM points, 300mm from power. Will spec the coax cable as above.


Thanks

[Alucidnation]

Surely your electrician would be better to ask as he is on site?

Anyway, on a full rewire there should be virtually no reason why any coax and cat cables would be run next to any power.

[Andeh1]

I would argue over any distance likely to be seen in a domestic house running cat6 alongside power for a few feet here & there will make absolutely no noticeable difference. Same with the cat6 bend radius' and clipping techniques etc etc....

For what you will be using it for you could tie the stuff in knots & not notice any difference.

Just common sense & best practise as much as possible, but don't loose sleep over it!

[Alucidnation]

So you don't think voltage appearing on your coax and network cables is a problem?

Cool.

[crmcatee]

Andeh1 said:

I would argue over any distance likely to be seen in a domestic house running cat6 alongside power for a few feet here & there will make absolutely no noticeable difference. Same with the cat6 bend radius' and clipping techniques etc etc....

For what you will be using it for you could tie the stuff in knots & not notice any difference.

Just common sense & best practise as much as possible, but don't loose sleep over it!

People wonder why they can't run stuff that they want over badly installed systems. The above is the reason.


Best practice is to follow the installation standards - following the bend radius recommendations, clipping as well as main voltage separation recommendations as well as good termination practices.

[Alucidnation]

crmcatee said:

Andeh1 said:

I would argue over any distance likely to be seen in a domestic house running cat6 alongside power for a few feet here & there will make absolutely no noticeable difference. Same with the cat6 bend radius' and clipping techniques etc etc....

For what you will be using it for you could tie the stuff in knots & not notice any difference.

Just common sense & best practise as much as possible, but don't loose sleep over it!

Best practice is to follow the installation standards - following the bend radius recommendations, clipping as well as main voltage separation recommendations as well as good termination practices.

[Alucidnation]

It's more about possible dangerous voltages appearing on the cables more than affecting performance though.

[dhutch]

Understand we could talk about this all day.

It will not be an issue to maintain 300mm separation from poeert for the majority of the the install, and there appears to be no issue for running network with coax.

However for some areas being able to make less holes through/behind period plasterwork is significantly important, especially for cables that may never even be used. I also presume a network speaker if ever used is likely to be much closer to 10/100 then base 1000.
People run network cables in a buddle of other cables from the wall socket to the back of their pc and the like.

Obviously we will try not to link it or clip it with the wrong clips.

The electrician is a top bloke who's doing a cracking job of reasonable sensitivity rewiring the house to a good standard, but he is also not a network installer, so I'm just double checking before talking the final details of job over to ensure the compromises are sensible.

Thanks

Daniel

[dhutch]

I have another similar thread in the Hifi section asking about the audio side. But what is network like for running next to speaker cables?


Daniel

[Mr Pointy]

dhutch said:

I have another similar thread in the Hifi section asking about the audio side. But what is network like for running next to speaker cables?

No issue at all. The level of cross interference is miniscule.

[megaphone]

What he said. No issues.

[mikeveal]

Alucidnation said:

It's more about possible dangerous voltages appearing on the cables more than affecting performance though.

The electromagnetic field generated by the current running in the Live wire will (on the macro scale) be cancelled by the equal and opposite current running in the Neutral wire. Thus with no net field around the mains cable, there will not be a significant current induced in the victim cable.

This is true if the victim cable stays no close to the mains cable than 5 times the separation between the Live and Neutral cables.
It is true at mains frequencies. At much higher frequencies it's not always true. If you have a switch mode power supply that hasn't passed FCC and is injecting conducted noise AND you have a mismatch in length between live and neutral.

The victim cable we're talking about is ethernet. It's a twisted pair, so even if there is a voltage induced (say by running it immediately adjacent to a mains cable) it will be present in equal amounts on both halves of the twisted pair. This is called common mode noise and ethernet jacks have built in magnetics to remove common mode noise.

In short, it's sensible to keep a bit of separation. But don't over think it. There will be no harm caused to your ethernet device (& no drop in speed), or to your TV if you do run parallel to a mains cable. Shove it up the same channel in the wall, space it out under the floorboards.

Don't believe me? Read 'A handbook of black magic.' & 'Advanced black magic' by H. Johnson.

[Mr Pointy]

mikeveal said:

Alucidnation said:

It's more about possible dangerous voltages appearing on the cables more than affecting performance though.

The electromagnetic field generated by the current running in the Live wire will (on the macro scale) be cancelled by the equal and opposite current running in the Neutral wire. Thus with no net field around the mains cable, there will not be a significant current induced in the victim cable.

This is true if the victim cable stays no close to the mains cable than 5 times the separation between the Live and Neutral cables.
It is true at mains frequencies. At much higher frequencies it's not always true. If you have a switch mode power supply that hasn't passed FCC and is injecting conducted noise AND you have a mismatch in length between live and neutral.

The victim cable we're talking about is ethernet. It's a twisted pair, so even if there is a voltage induced (say by running it immediately adjacent to a mains cable) it will be present in equal amounts on both halves of the twisted pair. This is called common mode noise and ethernet jacks have built in magnetics to remove common mode noise.

In short, it's sensible to keep a bit of separation. But don't over think it. There will be no harm caused to your ethernet device (& no drop in speed), or to your TV if you do run parallel to a mains cable. Shove it up the same channel in the wall, space it out under the floorboards.

Don't believe me? Read 'A handbook of black magic.' & 'Advanced black magic' by H. Johnson.

I gave up responding when the "how far apart" question is asked on here as you simply get drowned out with posters claiming your house will burn down for certain if you don't have a couple of meters of seperation. In an industrial situation with machines or heavy plant it might be different & we certainly used to take a bit of care when the studio lighting dimmers were rack mounted above the lighting grid as the mains waveforms were truly horrible but in a domestic situation there is simply no issue.

[mikeveal]

Mr Pointy said:

gave up responding when the "how far apart" question is asked on here as you simply get drowned out with posters claiming your house will burn down for certain if you don't have a couple of meters of seperation. In an industrial situation with machines or heavy plant it might be different & we certainly used to take a bit of care when the studio lighting dimmers were rack mounted above the lighting grid as the mains waveforms were truly horrible but in a domestic situation there is simply no issue.

It's hardly surprising people don't get it. Transmission line stuff is a niche speciality of a niche speciality (electronics). It was my day job for ~20 years, very few engineers I come across can actually apply the theory.

[dhutch]

Mr Pointy said:

o issue at all. The level of cross interference is miniscule.

Ok, the speaker cable won't effect the network or vice versa? I'm probably more worried about the speakers picking something up than the other way around.
As said, I'm using T&E to allow the option of sending power down it, so will try and have some separation but obviously the core aim is for the intial intended operation.


Most music is expected to come from a Cromecast audio located with the amp. But I thought I would also run a couple of 'line-in' cables (cable spec tbc) to core locations (kitchen, my best guess for tv location, maybe the office) so I can plug in a local source/sources in these rooms. Not sure if these might be more sensitive to running too close to power, and or speaker-level cables, network?

In an ideal world im sure everything would be run at 300 centres, but the hall is only a finite width and each spacing in a line of floorboards or lath & plaster ceiling I have to cut out and rip up!


Thanks again.

[Mr Pointy]

dhutch said:

Mr Pointy said:

o issue at all. The level of cross interference is miniscule.

Ok, the speaker cable won't effect the network or vice versa? I'm probably more worried about the speakers picking something up than the other way around.
As said, I'm using T&E to allow the option of sending power down it, so will try and have some separation but obviously the core aim is for the intial intended operation.

Most music is expected to come from a Cromecast audio located with the amp. But I thought I would also run a couple of 'line-in' cables (cable spec tbc) to core locations (kitchen, my best guess for tv location, maybe the office) so I can plug in a local source/sources in these rooms. Not sure if these might be more sensitive to running too close to power, and or speaker-level cables, network?

In an ideal world im sure everything would be run at 300 centres, but the hall is only a finite width and each spacing in a line of floorboards or lath & plaster ceiling I have to cut out and rip up!

Thanks again.

Neither the speaker cable or the network cable will affect each other. The design of the network cable makes it very resistant to interference & the signal level on the network cable means it just doesn't have the strength to impact on the speaker signal. The only time you might hear something on a speaker cable is if it was run very close to a mains cable whch has switching transients on it, like a fan heater switching on & off. 300mm is lovely, but just get as much as you can.

I saw your question about line level cabling in the other forum but I'll answer here. The problem is that most domestic 'line' level signals are unbalanced & not particularly high level. The balancing of a signal is what helps so much with interference rejection (which is why network data signals & cables are balanced) but unbalanced audio is more susceptible. Without going crazy on cable spec I'd suggest using a twin core screened cable like this one:
https://www.canford.co.uk/CANFORD-FST-HD-FOIL-SCRE...

I'll try & find another source as I don't think Canford will sell to you but there are lots of different versions of this cable so it's not difficult to purchase.

If you are using it as unbalanced then just connect the screen & the black core together but be aware there can be issues with ground loops causing hum with unbalanced signals over long cables. It's really only meant to go a few of meters but it's often pushed further. If you do use it & get hum there are things you can do (balancing units or even transformers) but at least you'll have the right cable installed. These cables are happy near speaker or network cables, slightly riskier running them for any distance near a power cable. Of all the signals you have mentioned so far the unbalanced audio is the trickiest to handle.

[dhutch]

Mr Pointy said:

either the speaker cable or the network cable will affect each other. The design of the network cable makes it very resistant to interference & the signal level on the network cable means it just doesn't have the strength to impact on the speaker signal. The only time you might hear something on a speaker cable is if it was run very close to a mains cable whch has switching transients on it, like a fan heater switching on & off. 300mm is lovely, but just get as much as you can.

I saw your question about line level cabling in the other forum but I'll answer here. The problem is that most domestic 'line' level signals are unbalanced & not particularly high level. The balancing of a signal is what helps so much with interference rejection (which is why network data signals & cables are balanced) but unbalanced audio is more susceptible. Without going crazy on cable spec I'd suggest using a twin core screened cable like this one:
https://www.canford.co.uk/CANFORD-FST-HD-FOIL-SCRE...

I'll try & find another source as I don't think Canford will sell to you but there are lots of different versions of this cable so it's not difficult to purchase.

If you are using it as unbalanced then just connect the screen & the black core together but be aware there can be issues with ground loops causing hum with unbalanced signals over long cables. It's really only meant to go a few of meters but it's often pushed further. If you do use it & get hum there are things you can do (balancing units or even transformers) but at least you'll have the right cable installed. These cables are happy near speaker or network cables, slightly riskier running them for any distance near a power cable. Of all the signals you have mentioned so far the unbalanced audio is the trickiest to handle.

Sounds fair to me. Thanks again

I understand it's a bit of an ask, as you say I guess the key is to ensure the cable is right. Worse case I guess you can run it through a DI Box!

I have some sound knowledge from being in the venue crew at the students in, but I spent more time with the lighting, and obviously the day to day doesn't include any design of hardwired systems, certainly not anything domestic.

Just got to decide where I want which wall box! Spent two weeks trying to keep ahead in the electrician on socket switch and lamp locations.


Daniel