distance between tv aerial and mains socket?

Feb 22, 2009 29 Replies

Is there a recommended distance to keep between a tv aerial socket and a mains socket? I'm thinking if they are too close would the aerial pick up interference? I had a quick flick through the OSG but all I coul;d find was something about keeping telephone lines 50mm away from mains cables, which IMO seemed a very small separation but entirely irrelevant to my original question! TIA, Stephen.


In message , Stephen wrote

You can un-screened and fully screened TV aerial face plates

You can get 100% copper screened aerial down-lead cables and cable with barely any screening at all.

Terrestrial digital TV can suffer from local electrical interference so the 'safe' distance between a mains socket and an aerial wall plate socket may be dependant on the quality of cable and face plate being used.

I'd be most surprised if mains carried frequencies high enough to cause problems - and in any case decent cable should be pretty well screened.

It certainly does...my thermostats cause horrendous arcing and make rude wounds on every radio and TV...

That's likely radiated rather than carried by the cabling. Don't your neighbours complain?

Considering the jumble of cables, both mains and signal, all in close proximity behind the average TV set I doubt if the distance between the sockets is significant at all.

It depends what the interference is being caused by. The coax can be a number of wavelengths long and resonate on certain frequencies. At VHF & UHF the coax can act as a number of wavelengths and with increased gain, on MW and SW bands the coax can be one wavelength. Interference is usually picked up on the braid/screen. The same goes for mains wiring and phone wiring. If he meant mains spikes being picked up by being inductively coupled, then that is possible if the coax runs along side mains wiring for any length. A mains and RF socket can be right next to each other, but I wouldn't run cables alongside each other.

You completely misunderstand how and what interference is. Some basic theory on RF and mains via Google should get you started. Then you can progress to understanding how coax works and why it can pick up other signals! Then you can look at mains filtering, RF filtering, inductive coupling and whatever else you want to read up on. I take it you would have difficulty understanding how a new all singing digital system would be affected by "interference" when all the adverts seem to state anything "digital" is "interference free". The man's neighbours are on a different phase so that is why they would not have the thermostat problem and it would be too weak a few houses away. You might like to look at mains distribution systems too. I think you're in for a busy weekend, at least you have admitted you have little knowledge.

As I understand it the OSG is about safety, not interference. If you follow the rules in there you are not guaranteed an interference-free life, but you are less likely to get 240v down your lughole when aunty Maureen gives you a tinkle.

To reduce interference you should either used a screen aerial socket or make you own using F Plugs and an F barrel - as described in some of the technical documents on the CAI web site.

How do I get "the mains" via Google? How much do they charge per kWh? Is it free like their other services.

Oh and is this -> . a piece of your brain? Or is it all of it?

I'd say I've got the normal number of thermostats here and perhaps more than the normal amount of AV equipment - and have never heard or seen a thermostat operate on any of it.

If you do something is very wrong. Are you in a very poor signal area for TV and radio?

More likely the arc suppression capacitor across the thermostat contacts has failed.

Or non existent. But on all of them?

But most recent ones should conform to pretty strict regs as regards interference.

Thought I'd just read this again...

So what signals are being radiated by mains that this might apply to?

Co-ax in use for MW and SW? My AM aerial uses a balanced feeder. For a very good reason.

Mains and telephone wiring has a braid/screen?

That at least is reasonable.

It's against regs anyway.

Ahh, didn't notice plural.

Indeed.

Thanks. When I drafted my post I did add "or is the 50Hz frequency of the mains too low to affect UHF" (or words to that effect) but I had last minute nerves that there might be higher frequency harmonics or something, so I deleted it. The other posts contain valid points about screening, F connectors, etc. Like someone said, mains and uhf are next to each other in the tv so this has reassured me. Thanks again.

He's the RF 'expert' who tends to rubbish everything Bill Wright says. Know which one I'd believe.

Me2 and sneering at your knowledge of RF was umm foolish.

Not really - my expertise if you can call it that is at rather lower frequencies. ;-)

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