Re: shielded tp ethernet cable

On Tue, 7 Oct 2008 20:27:40 +0100, mark <(E-Mail Removed)>
wrote:

>
>Can shielded cable be run in the same duct as domestic mains cables?

yes - it can.

is it a good idea - definitely not, since the insulation isnt good
enough.

is it legal - probably not, since you are not following the IEEE UK
code of practice for electricity wiring for segregation of low and
mains voltage cabling.
--
Regards

(E-Mail Removed) - replace xyz with ntl

In message <(E-Mail Removed)>, Stephen
<(E-Mail Removed)> writes
>On Tue, 7 Oct 2008 20:27:40 +0100, mark <(E-Mail Removed)>
>wrote:
>
>>
>>Can shielded cable be run in the same duct as domestic mains cables?
>
>yes - it can.
>
>is it a good idea - definitely not, since the insulation isnt good
>enough.
>
>is it legal - probably not, since you are not following the IEEE UK
>code of practice for electricity wiring for segregation of low and
>mains voltage cabling.

It's beginning to look as if every homeowner in the UK is going to need
to have their electricity and heating systems certified before they are
allowed to sell. It may be possible to run low voltage and mains cable
in parallel, but whether it is advisable is a very different issue.


--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author.

In message <S$v$(E-Mail Removed)>, Bernard Peek <(E-Mail Removed)>
writes
>In message <(E-Mail Removed)>, Stephen
><(E-Mail Removed)> writes
>>On Tue, 7 Oct 2008 20:27:40 +0100, mark <(E-Mail Removed)>
>>wrote:
>>
>>>
>>>Can shielded cable be run in the same duct as domestic mains cables?
>>
>>yes - it can.
>>
>>is it a good idea - definitely not, since the insulation isnt good
>>enough.
>>
>>is it legal - probably not, since you are not following the IEEE UK
>>code of practice for electricity wiring for segregation of low and
>>mains voltage cabling.
>
>It's beginning to look as if every homeowner in the UK is going to need
>to have their electricity and heating systems certified before they are
>allowed to sell. It may be possible to run low voltage and mains cable
>in parallel, but whether it is advisable is a very different issue.
>
>
I was initially concerned about the interference to data transfer but I
see the problem now with the electric itself.

--
Mark Roberts

In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> On Tue, 7 Oct 2008 20:27:40 +0100, mark <(E-Mail Removed)>
> wrote:
>
> >
> >Can shielded cable be run in the same duct as domestic mains cables?
>
> yes - it can.
>
> is it a good idea - definitely not, since the insulation isnt good
> enough.
>
> is it legal - probably not, since you are not following the IEEE UK
> code of practice for electricity wiring for segregation of low and
> mains voltage cabling.
>
Nothing to do with the IEEE - that USA. We have the IEE over here :-)

AFAICS the new 2008 17th edition of the IEE Wiring regulations requires
a RCD even on data cables (!!!) unless there is physical separation of
the data and mains cabling. Because of this, I would never run them
together without obvious physical and electrical separation (e.g. no
touching cables and not in the same duct unless there is a grounded
divider in the duct). This way, the data cables do not form part of the
mains electical installation so would not be subject to the requirements
for mains installation certification after installation.

That said, mains cable is an excellent aerial picking up and re-
radiating all sorts of HF signals in the data bands, not to mention
switching transients with components way above HF. This would be coupled
into the data cable shield, which is only grounded at the end. Hence any
induced HF current runs all the way along the shield to the ground
point. Since the shield is parallel to, and close to, the data wires,
who knows what interference they will see? Another argument for
separating mains and data IMO.
--
John W
To mail me replace the obvious with co.uk twice

In article <(E-Mail Removed)>,
mark <(E-Mail Removed)> writes:
> I was initially concerned about the interference to data transfer but I
> see the problem now with the electric itself.

The data transfer will work fine (and possibly even
better with unshielded cable).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article <(E-Mail Removed)>,
John Weston <(E-Mail Removed)> writes:
> Nothing to do with the IEEE - that USA. We have the IEE over here :-)
>
> AFAICS the new 2008 17th edition of the IEE Wiring regulations requires
> a RCD even on data cables (!!!) unless there is physical separation of
> the data and mains cabling. Because of this, I would never run them
> together without obvious physical and electrical separation (e.g. no
> touching cables and not in the same duct unless there is a grounded
> divider in the duct). This way, the data cables do not form part of the
> mains electical installation so would not be subject to the requirements
> for mains installation certification after installation.

IEE regs cover all premises wiring, including data, phone, doorbell,
etc. not just mains. There are exceptions where other regs take over,
such as "suppliers works" (supply wiring up to and including your
meter), wiring in a lift shaft, and lightning conductors.

Having said that, the IEE regs coverage of extra low voltage data is
really rather incompetent. Insulation barrier is fine, but separatation
to prevent interference is now silly -- just about every signalling
protocol in the last 40 years has been design to run alongside mains
wiring, in recognition of what happens in real life.

> That said, mains cable is an excellent aerial picking up and re-
> radiating all sorts of HF signals in the data bands, not to mention
> switching transients with components way above HF. This would be coupled
> into the data cable shield, which is only grounded at the end. Hence any
> induced HF current runs all the way along the shield to the ground
> point. Since the shield is parallel to, and close to, the data wires,
> who knows what interference they will see? Another argument for
> separating mains and data IMO.

That's also the argument for not using shielded cable in this case.
(The shield is more likely to induce noise than it is to protect
from it, and anyway, very few people get the grounding connections
for it right.) If you might want to use the twisted pair for something
else one day, then it might be worth using screened in case that
needs it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In message <48ee0824$0$513$(E-Mail Removed)>, Andrew Gabriel
<(E-Mail Removed)> writes
>In article <(E-Mail Removed)>,
> mark <(E-Mail Removed)> writes:
>> I was initially concerned about the interference to data transfer but I
>> see the problem now with the electric itself.
>
>The data transfer will work fine (and possibly even
>better with unshielded cable).
>
Really?
Will the EMF from the mains cables not degrade the data signal?
What is shielded cable for then?
--
Mark Roberts