cable separation

Nicktendo64 · Dec 2, 2008

Hi everyone. I have been asked to find out a minimum separation distance for a RG59 coaxial cable and mains cables.
The job that is has come up on is a CCTV installation running up a pipe with fibre cables on one side, the RG59 cable on the other side and 2 mains cables running through the middle. Im not sure on the size of the pipe as i havent seen this job yet.
I have looked around the web for answers but nothing has come up yet, if any of you can help it will be greatly appreciated.
Cheers
Nick

DanBrown · Dec 3, 2008

I think that around 300mm is enough in a typical domestic house. At end of day it all depends on the amount of cables that are being run and the amperage draw. If you have a low amperage circuit it is less likely to effect the transmission of data due to the magnetic field encured. If you have lots of cable bunced or run on a cable tray etc the fields around the cables all gather together and create a large magnetic field, and then greater distances need to be considered.

Hope this helps and not confusing.

Spudnik · Dec 3, 2008

Page 62 OSG gives guidance on mains cables and phone cables which is 50mm.

However, cant find anything on RG & fibres.

Best have a look at a cables manufacturers website.

mjvor · Dec 3, 2008

Check out Appendix I in IEE Guidance Note 1
It says
screened IT cable and screened power cable (ie armoured) do not need separating for EMC reasons

Also
unscreened power eg T&E and screened IT, the separation is 50mm - again for EMC reasons.
Segregation of voltage bands overrides this as per regs

Kris · Dec 6, 2008

I can't see the fibres needing any separation if you don't want to, as they are non conductive and you cant introduce an emf into them. As far as the RG59 is concerned if you use a cable with 230V rated insulation and screening you could run it with the power cables. As a rule we separate them but if you cant you must make sure they are 230V rated and screened.

OilBeDamned · Dec 6, 2008

If the cable is screened will give you a difference as to the degree of seperation.

johnnyb · Dec 7, 2008

I have in specs we have worked on 100mm min running parrallel any above this is a bonus, and it does not matter about crossing any mains as this is usually unavoidable anyway.

OilBeDamned · Dec 7, 2008

johnnyb said:
I have in specs we have worked on 100mm min running parrallel any above this is a bonus, and it does not matter about crossing any mains as this is usually unavoidable anyway.

The last job we were on doing fibres and comms they demanded 100mm seperation from power cables, 75mm from control cabling and when you had to cross you were only allowed to cross at 90 degrees. It was MoD spec which is way over whats required.