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Live TV arial cable

Dutch

By Dutch
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Dutch

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Today i was messing with the coax tv cable and noticed when i was holding both coaxial plugs i got a mild shock so i got out the metre and tested the current and got a reading of around 100 volts.I have one tv arial into a splitter to two Tvs what tests can i conduct to find out where this voltage is coming from.I am on shoreline 240v also have an inverter which is switched off i checked between one coax plug and the case on the digi box.

Mick

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WotEver Veteran II

WotEverDonate to Canal World

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Today i was messing with the coax tv cable and noticed when i was holding both coaxial plugs i got a mild shock so i got out the metre and tested the current and got a reading of around 100 volts.I have one tv arial into a splitter to two Tvs what tests can i conduct to find out where this voltage is coming from.I am on shoreline 240v also have an inverter which is switched off i checked between one coax plug and the case on the digi box.

Mick

 

Hi Dutch,

 

I've many times seen TVs with volts on the aerial socket. Particularly cheap TVs and even more often when Live and Neutral are incorrectly wired. Never enough current to harm, but disconcerting nonetheless.

 

To find out where it's coming from is just a process of elimination, so let's start with the most likely. Firstly you need a good known earth from which to take the measurements. You can either connect a wire to the earth pin of a 13A plugtop, or you could run a wire from your common earthing point where it's bonded to the hull, or you could use the metal case of some piece of electrical apparatus. Whatever you use, connect one side of your multimeter to the earth and then touch the other lead to the aerial socket on your TV. If that's not reading, then try checking the aerial plug... etc, etc until you find the one piece of equipment that's leaking.

 

Hope that all makes sense,

Tony :lol:

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Dutch Collaborator

Dutch

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Hi Dutch,

 

I've many times seen TVs with volts on the aerial socket. Particularly cheap TVs and even more often when Live and Neutral are incorrectly wired. Never enough current to harm, but disconcerting nonetheless.

 

To find out where it's coming from is just a process of elimination, so let's start with the most likely. Firstly you need a good known earth from which to take the measurements. You can either connect a wire to the earth pin of a 13A plugtop, or you could run a wire from your common earthing point where it's bonded to the hull, or you could use the metal case of some piece of electrical apparatus. Whatever you use, connect one side of your multimeter to the earth and then touch the other lead to the aerial socket on your TV. If that's not reading, then try checking the aerial plug... etc, etc until you find the one piece of equipment that's leaking.

 

Hope that all makes sense,

Tony :lol:

 

I will try that in the morning,if or when i trace the source what can i do to cure it?

Mick

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bramley Community Regular

bramley

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i always remember on a old philips tv holding the tv arieal, trying to find the tv socket for it, and feeling my hands get a small consitant shock...

 

no idea why, always put it down to passing currents

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twocvbloke Rising Star

twocvbloke

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Had the same experience myself with many TVs, I think it's down to modern TVs not being earthed, being Double Insulated, so any voltage that develops on the internal ground just hangs about waiting for you to, ahem, finger the socket and get a shock.... :lol:

 

It's annoying, but, it's not life threatening, well, I don't think it is, maybe for those with pacemakers and personal defib things... :lol:

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Chris J W Influencer

Chris J W

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No Chris i have not got amplified arial

Mick

 

The TV could still be supplying power even if it's not being used. For instance, my HUMAX Freeview PVR has the aerial power on by default.

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Dutch Collaborator

Dutch

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The TV could still be supplying power even if it's not being used. For instance, my HUMAX Freeview PVR has the aerial power on by default.

Strange thing is i can not now get a reading as i did last night??When i went to plug the coax plug into the arial socket i got a mild spark

Mick

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WotEver Veteran II

WotEverDonate to Canal World

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Strange thing is i can not now get a reading as i did last night??When i went to plug the coax plug into the arial socket i got a mild spark

Mick

 

That's common, too.

 

Keep the mulimeter and earth wire handy, so the next time it happens you can confirm exactly where it originates.

 

It might also only happen when the TV is warm or when it's cold....

 

T :lol:

 

my HUMAX Freeview PVR has the aerial power on by default.

 

Think you'll find that's around 12V, not 100V.

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ChrisPy Veteran

ChrisPy

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I had to fiddle around with the aerial socket in an old TV to try to get a better connection. I forgot that the TV chassis is live. The aerial socket came into contact with the chassis and I got a shock.

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Semitrad Collaborator

Semitrad

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many modern flatscreen sets run from 12v which is derived from the mains via an isolated powerunit, they are very safe and you are very unlikely to get a shock from these.

The previous generation with CRTs were "double insulated" the mains supply connected to an onboard power supply and was never connected to the chassis, often isolated from it via a transformer, with controlling feedback using an opto-isolator.

Before that, the mains was connected directly to one side of the chassis and the ae socket had it's own isolating components incorporated, these could fail, leaving the socket live and possibly the antenna as well, not good news for the unwary aeriel installer on his ladder! In practice this rarely happened as the antenna is usually a short circuit to 50Hz (Almost said cycles) and all that happened was an almighty bang as the fuses blew.

Very hard to say where the leakage is from, bear in mind that if you were to sit on a power cable as the birds are able to do with impunity, you would be quite safe until you touch the ground.

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