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Sky Digital BSkyB, Freesat & Saorsat support forum
Sky & Freesat fringe reception
Installing Dishes In Spain for 2E Chit-Chat
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<blockquote data-quote="Menorca Man" data-source="post: 919131" data-attributes="member: 393212"><p>Yes and no! True when preventing the possibility of electrocution but different if you are dealing with very low voltage RF or AF signals over long cable runs. Earthing both ends of a screened cable increases the possibility of introducing electrical noise due to an earth loop. There are many articles about this phenomena on the Internet and the extract below is from Wikipedia article <a href="http://en.wikipedia.org/wiki/Ground_loop_(electricity)" target="_blank">http://en.wikipedia.org/wiki/Ground_loop_(electricity)</a> in which I've highlighted the conflict between the two requirements.</p><p></p><p>"The causes of ground loops have been thoroughly understood for more than half a century, and yet they are still a very common problem where multiple components are interconnected with cables. The underlying reason for this is <strong>an unavoidable conflict between the two different functions of a grounding system: reducing electronic noise and preventing electric shock</strong>. From a noise perspective it is preferable to have "single-point grounding", with the system connected to the building ground wire at only one point. National <a href="http://en.wikipedia.org/wiki/Electrical_code" target="_blank"><u>electrical codes</u></a>, however, often require all AC powered components to have third-wire grounds; from a safety standpoint it is preferable to have each AC component grounded. However the multiple ground connections cause ground loops when the components are interconnected by signal cables, as shown below."</p></blockquote><p></p>
[QUOTE="Menorca Man, post: 919131, member: 393212"] Yes and no! True when preventing the possibility of electrocution but different if you are dealing with very low voltage RF or AF signals over long cable runs. Earthing both ends of a screened cable increases the possibility of introducing electrical noise due to an earth loop. There are many articles about this phenomena on the Internet and the extract below is from Wikipedia article [url]http://en.wikipedia.org/wiki/Ground_loop_(electricity)[/url] in which I've highlighted the conflict between the two requirements. "The causes of ground loops have been thoroughly understood for more than half a century, and yet they are still a very common problem where multiple components are interconnected with cables. The underlying reason for this is [B]an unavoidable conflict between the two different functions of a grounding system: reducing electronic noise and preventing electric shock[/B]. From a noise perspective it is preferable to have "single-point grounding", with the system connected to the building ground wire at only one point. National [URL='http://en.wikipedia.org/wiki/Electrical_code'][U]electrical codes[/U][/URL], however, often require all AC powered components to have third-wire grounds; from a safety standpoint it is preferable to have each AC component grounded. However the multiple ground connections cause ground loops when the components are interconnected by signal cables, as shown below." [/QUOTE]
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Installing Dishes In Spain for 2E Chit-Chat
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