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Topic Title: Running TV Coaxial with Power
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Created On: 06 March 2013 08:18 PM
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 06 March 2013 08:18 PM
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MrOther

Posts: 530
Joined: 08 June 2010

Planning to run a TV coaxial cable with new socket power cables (T/E) as it keeps all the cables in the safe zones (as I don't believe their are any caveats for differences in voltages or use) and it saves me butchering the wall with loads of chases.

My limited knowledge tells me that running these two cables would causes a small inductive exchange and this could manifest as a bad signal.

If this is true, would running the coaxial in PVC oval conduit be enough?

Many thanks as always.
 06 March 2013 08:53 PM
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DOUGIE1000

Posts: 4159
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Hi,

We have always kept 240volt separated from phone, data, tv, video way I was taught.

-------------------------
Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 06 March 2013 09:01 PM
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daveparry1

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I spent over 40 years as a TV engineer and I can't ever remember having a problem with this, although I must admit that I do keep them seperated wherever possible!

Dave.
 06 March 2013 09:08 PM
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MrOther

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Dougie, thanks for your prompt reply.

It is my understanding that Band I & II seperation has been relaxed as long as the cables present can withstand the highest voltage present.

As this isn't applicable here the cables need seperating.

I intend to make the chase big enough to space them apart physically, but where this may not be possible I was hoping to use oval conduit to create the barrier of seperation.

As I say, my only fear is not knowing whether the conduit will shield the coaxial cable enough from the power.
 06 March 2013 09:08 PM
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MrOther

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Originally posted by: daveparry1

I spent over 40 years as a TV engineer and I can't ever remember having a problem with this, although I must admit that I do keep them seperated wherever possible!



Dave.


Is there alot to learn in that side of things Dave?
 06 March 2013 09:08 PM
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MrOther

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Originally posted by: daveparry1

I spent over 40 years as a TV engineer and I can't ever remember having a problem with this, although I must admit that I do keep them seperated wherever possible!



Dave.


Is there alot to learn in that side of things Dave?
 06 March 2013 09:34 PM
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slittle

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The "shield" is in the design of the coax cable. Oval conduit is made of plastic (or was last time I used it) so has no shielding properties at all other than keeping the plaster off the cable.

However, the copper braid and possibly foil inside the pvc jacket of the coax makes an excellent shield for both interference from outside of the cable getting in and equally keeping the signal carried on the centre conductor inside the cable.

I try and keep them apart where I can under floors etc but down the wall, it's normally all in one wide chase although there's usually a couple of inches between them by the time the boxes have settled.

Stu
 06 March 2013 09:46 PM
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daveparry1

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In a word yes! Many different types of circuits to find your way around, UHF frequencies, line and frame timebase circuits, switched-mode power supplies, line flyback generated EHT (extra high voltage) supplies for the final anode of the tube of around 30 kV, PAL colour decoder circuits etc,etc. These were all repaired down to component level, so experience of many different models was necessary to be efficient as an engineer, especially when working for a rental company and being given a dozen colour calls a day to sort out! (there were of course some easy calls) Things are a lot different now of course, most of it is now virtually non-repairable, surface mounted ic chips with around 100 connections on a chip about the size of a small postage stamp! I don't think much is repaired in that trade these days, most of it just gets swapped over on warranty jobs or thrown away by the consumer when it goes wrong after 2-3 years. You only have to look at what's thrown down the local tip to see that, some of it looks almost brand new. I remember when a tv wasn't considered old untill it had about 8 years of use!

Dave.
 06 March 2013 10:21 PM
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Dale76uk

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use screened coax :-)
 06 March 2013 10:26 PM
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daveparry1

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All co-ax is screened Dale!
 06 March 2013 10:28 PM
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Dale76uk

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re-phrase - use copper screened coax -

like
http://www.smithandlow.com/tv-...x-cable-per-meter.html
 06 March 2013 10:30 PM
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Dale76uk

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most coaxial cable dave has a braided copper 'shield' and not a copper screen
 06 March 2013 10:38 PM
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daveparry1

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The braiding is a screen, but agreed the cable with the copper foil in is better, although that was rarely used in tv work until sattelite tv came into being. Standard co-ax was almost always used until Sky came along except for in particularly difficult signal areas.
 07 March 2013 06:13 PM
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M.Joshi

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If you use a good quality coax such as WF100 which has two screens, then you should be fine for satellite or digital TV. What I have learnt is to always run an extra feed for future services e.g. to use them for satellite in the future.

Spurious noise from switched mode power supplies is more likely to creep in at the termination points so make sure you use good quality fittings/plates. The plates with a complete screened enclosure are best.

I'm sure you won't, but steer clear of the cheap (thin) coax available from the likes of high street catalogue and some DIY stores etc.! It is often described as 'low loss' but only relies on single braid screening.

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M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!
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