digi Coax near mains cable

[Adrian80]

Hi running some digi coax cable for the tv, i was wondering if its really a bad idea to run it next to 2.5mm t&e's.

I just read that you shouldnt do this with telephone cable, but i think telephone cable isnt sheilded so this is why it applies to this.

Isn't coax cable shielded so i dont have to worry about this?

Cheers

Adrian

 

[RF Lighting]

No, you may find you have issues with the signal if you run it near mains.

coax is screened because it carries a very low powered signal and needs to be amplified at the TV.

Any 'noise' from the mains cables gets amplified too.

 

[Adrian80]

Cheers RF,

if a little bit of coax is running parallel to mains cable do you think this will be a problem.

I have some trunking running up the wall into the loft, inside the trunking will be a shower cable and the lights. also i have some short runs under the floor where everything runs together.

Is it just a case minimise the number of parallel runs, and hope for the best?

cheers
Adrian

 

[RF Lighting]

Yep thats all you can do.

Crossing one another at 90 degrees is ok, and just kkep as muck distance as practical between the two types.

You arn't planning to run the coax in the same trunking as mains cables are you?

 

[Adrian80]

Well i was,

but i think two bits of trunking up the back wall is probably the best idea.

Cheers for your input.

Its amazing what they leave out of those diy encyclopaedias.

Cheers for the speedy response.

can i run telephone, burglar alarm, and coax all together? or does the same problem apply?

Adrian

 

[aptsys]

I'd choose to keep the coax away from telephone and alarm cables if possible, but there's only so much separation you can achieve! If it's 2 or 3 meters don't worry, if it's the entire length of the house then try to find another route.

 

[Adrian80]

Cheers guys for the input.

Will try and keep the whole lot separated as much as possible.


advice is much appreciated!

Adrian

 

[AlanE]

Isn't coax cable shielded so i dont have to worry about this?

Coaxial cable is only shielded if it has two 'outer' concentric conductors.

Coaxial cable cannot be considered as a cable with a centre conductor that carries the signal currents with an outer shielding layer. It is much more complex than that. It is a 'transmission conductor' and as such has several complex design considerations if it is to work efficiently at high frequencies.

The diameter of the internal conductor in relation to the spacing of the outer determines the cables 'characteristic impedance' which must be correctly matched to the equipment at each end but more importantly the outer concentric layer also carries the signal currents.

Disconnect the braid from the TV aerial plug and the signal will be degraded to an intollerable level in all but extreemly strong signal areas.

 

[RF Lighting]

Coaxial cable is only shielded if it has two 'outer' concentric conductors..

Like broadcast qualtiy 'coax' is.

I'll get some from work tomorrow and show you a pic if you like.

 

[AlanE]

Fully aware that broadcast quality can have a second, and true screening layer, but sorry I fully believed this thread was concerned with domestic spec coaxial cable.

Broadcast quality is manufactured to a higher, and more rigid specification, than would be used on the average digi installation. Cost wise would amount to more than the cost of the entertainment equipment in the OP property.