View Full Version : OT: Running Cat5 near to mains cables

2007-04-07, 01:42

This is OT, but is losely linked to this: http://forums.slimdevices.com/showthread.php?t=22860

I'm currently getting Cat5 cable run to every room in a new house. The sparkys seem to be running the cable in the same channels as mains cable (240 volt). (I would have laid the cables myself, except the house builders didn't allow me).

Can anyone advise how big a problem this will be? The Cat5 will be used to power squeezeboxes, but I'm also thinking ahead to IPTV etc. In many cases the Cat5 is parallel to mains.

Many thanks,


2007-04-07, 03:44
If you are in UK then British Standard BS6701 2004 applies.

This is an extract from an information leaflet:


The New UK Installation Standard: BS6701:2004 has been written to reflect the publication of the BS EN50174 series of installation standards and the withdrawal of BS7718.

Now for Communications Cabling
The original BS6701:1994 was a code of practice basically dealing with apparatus connected to the public telecoms network. However the new standard now covers the installation, operation and maintenance of all types of "telecoms" (used to describe all forms of communications, i.e. voice and data) equipment and cabling.

It covers issues like hazards when installing telecoms and datacomms equipment and cabling, power supplies for equipment, and requirements for cabling in underground and aerial environments.

Installers & Owners too
The new BS6701 contains requirements not only for installers but also for the owners of the premises where the installation takes place.

Some aspects are mandatory
The new BS6701 is a BS specification and not just a code of practice. It is therefore a tool for determining conformance within contract law. In addition, it is referenced from the 16th edition wiring regulations making it a mandatory for every installation.

If you are worried, ask the housebuilder whether the standard is being applied.

2007-04-07, 03:59
Some useful info on separation found with google:


2007-04-07, 09:10
I had to put power (8kw cable), cat5 and phone line out from my house to an out building so as you can imagine it was a fair distance. Plenty of advice saying not to run your cat5's along with your power cables but I had no choice, it had to run under floors, loft etc - I had to rod them into place.

Good news is that I've not had any problems so in my opinion I wouldn't worry about it, it's cobblers.

2007-04-07, 09:41
That sounds encouraging. I won't know for sure until the house has power, and I can test the throughput with all the cables live.

But having read all the excellent postings in this thread, I'm somewhat relieved!


Mark Miksis
2007-04-07, 13:58
You probably won't have any trouble with the ethernet (especially if your runs are significantly shorter than the 100m limit). However, I have heard of people having problems with noise from the AC wiring if you plan to also run analog POTS over some of the cat5.