Cat5 cable should not be in the same pattress as mains electricity. Only
cables rated to 500V(?) insulation should be layed next to mains cable.
Alternatives are to separate by 50mm, or to provide extra insulation. The
last possibility might work in your case. I suspect running in plastic
conduit would provide sufficient insulation for your needs.
This is not for interference protection, but for electrical safety. I've
never found mains borne interference to be problematic with 100BaseT
ethernet, although I wouldn't be surprised if it was bad for Gigabit.
Depends if you cock it up. If you hit the cable with a hammer, then you have
a substantial chance of breaking the extremely delicate conductors. An
alternative is to hit the clip in without the cable present. Then use cable
ties (mucho cheapo) to tie the entire bundle of cables to the clip.
It's been a while since I looked, but last time I checked the IEE wiring
regs prohibited running comms cable in the same trunking or channel as
Double patress boxes are available with spaces for two single socket
outlet size plates and a separator between them, this would be an option
but you would need to route the cable separately.
Personally I wouldn't use CAT5 cable for telephones anyway, but that's
just me :-)
BS 7671 'Requirements for Electrical Installations (IEE Wiring Regulations
16th Edition' prohibits circuits of different voltage bands sharing the same
enclosure, except in special circumstances.
For the purposes of the Regulations, telecommunications circuits are
generally classed as being in Voltage Band I, whilst mains voltage circuits
are classed as Voltage Band II.
If you would like further information on the ways in which you can solve
your problem and still comply with the Regulations, post back.
There's a telephony regulation for telephony circuits connected
to the public telephone network which requires phone outlets to
be at least 50mm from mains outlets. Sorry I don't know the
reference for this.
Also, the separator in Double patress boxes does not seal the
two compartments if the box is recessed behind the plaster
surface any distance. (Indeed, I often end up passing earth
wires over the separator, making use of just this 'feature'.)
Personally I wouldn't do this, for safety reasons.
I would even avoid this. I've had to reroute one such cable because of hum
(floorboards up again!).
The problem is, UK phone extensions use three wires and are therefore not
fully "balanced", which makes them susceptible to crosstalk. You can solve
this by running only two wires and fitting a "PBX master" at the end to
generate the third, but this adds extra capacitance which can affect
performance (and be detected at the exchange). Having said all that, such
effects are slight and you won't notice any problems in the majority of
Not as long as you avoid compressing the cable. Also remember to avoid sharp
My final tip is to pull plenty of cables now so you won't have to do the job
again (even if you don't provide sockets for them all). I've pulled three
CAT5 (one for phone, one for ethernet, one spare) and TV coax to each room
in the house that might get used as a "study" and de-squeaked floorboards
while I was at it. Oh, and don't put the pattresses too close together - I
bought some brass TV and phone faceplates and found they were bigger than
the normal plastic ones and wouldn't fit!
Thanks to everyone for the replies. I hadn't even thought of the
electrical safety angle, I was more concerned about mains hum. Just as
well I posted.
I have been using 'dual' pattress boxes from Screwfix (ref 18949)
which take two 1-gang faceplates and have a metal 'partition'
screening each half from the other. However, to make it easier to get
the cables in I've fed them both through one hole and knocked out the
I guess these pattresses used properly would comply with the regs, is
that right Ross? Do you have other cunning plans which would help me
out?(Incidentally the other cables belong to a 5 amp, round-pin, mains
lighting circuit controlled from the light switch by the door and fed
from a FCU on the ring which I thought I may as well put in while I
was messing about with the floorboads).
Phil, I'm a bit worried about your reported mains hum. All the cat5
cables from the ground floor go up to the attic via a convenient shaft
I found which takes the soil stack up through the building. Between
two floors there is a length of 2.5mm T&E mains cable sharing the
shaft. I can't think of another convenient way of routing the cat5 up
through the building, so I think I'll have to risk it. If anything it
would be easier to find another route for the mains cable. All these
cables are dangling loosely in the vertical shaft, so they shouldn't
be in very close proximity. I think it's just going to be fingers
crossed (no, I can't hear a bee on the line dear).
Ivor, why wouldn't you use cat5 for telephones, am I missing
And as for clipping the things the consensus seems to be that it'll be
alright if I'm very careful, so I think I'll be having another evening
in the cellar very soon.
CAT5 is stranded conductor whereas normal phone cable is solid. Stranded
cores (at least in my experience) don't make as good a contact with the
displacement type terminations on a standard telephone socket.
Just my view, your mileage and/or experience may vary.
It might be worth you looking at FTP Cat5 cable which contains a foil
shielding to reduces interference. It's more expensive than the normal
UTP stuff, but you may find the extra shielding reduces the potential
interference from the mains cabling.
By default TiVos (well, UK series 1 models anyway) do not have any sort of
ethernet connection. They rely on a modem that does not work well over
cordless phone extensions.
TiVonet/TurboNet hacks are hardware based and give the TiVo an RJ45 ethernet
port. AirNet provides WiFi by using a pc card on a small adaptor. Both
require the box to be opened (and therefore kill any warranty). A ethernet
to wireless bridge wouldn't help as there would be nowhere on the TiVo to
plug it :-(
for more info.
Darren - this got slightly off topic really :-)
As the custodian of several thousand runs of Cat 5, I'd question
`reliable'. If a base station fails, chuck it and buy another one.
Diagnosing faults in Cat 5 is a real pain. Of course, in a res
environment you'll have plenty of margin for error, but one the cables
get over 50m long you need to be confident they're well terminated.
My DECT cordless phone never drops a call (unless i walk off 200 metres down
the road with it) & its as secure as it needs to be. Whoever bothers to hack
its encryption is going to be mighty disappointed with the information the
manage to hear!!
You will have to replace it then at some point.
> It's a mishmash of whatever was to hand, to be honest. From memory none of
The correct, approved cable is branded every metre down its length,
regardless of manufacturer. You will find that when the great analogue
closedown happens, or you want digital terrestrial beforehand, your
screening will be very likely inadequte. This will result in picture freeze
/ breakup every time your 'fridge' thermostat switches etc. Approved cable
also has better loss and tilt specifications than conventional run of the
AJL Electronics (G6FGO) : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk
I believe you, but at the moment single shielded coax comes from an antenna
in the roofspace to the lounge, the satellite and VCR carriers are added, it
goes to a distribution system under the stairs then back up to a bedroom
(sharing a cable duct with active 100 Mbit/s ethernet and three-wire phone
extensions), where it's decoded without any problems by a digital
terrestrial receiver. Touch wood. So it's not that bad. Admittedly we're
almost line of sight from Crystal Palace.
A good point to bear in mind if I have to lift the floorboards again though.
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