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Old 30-Nov-2010, 3:46 AM   #15
GroundUrMast
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Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,758
Anyone who reasons that a grounded antenna and mast may be attractive to atmospheric static is quite right.

However, reasoning that the antenna system will be safer if no effort is made to purposely ground and bond it, is flawed reasoning. In the case of a typical outdoor antenna installation, the antenna system is grounded the moment the coax is connected to the tuner input. This is because the coax offers a low impedance path from the antenna and mast, into the building, through the tuner and then to ground through the AC power wiring. Example cited previously: http://forum.tvfool.com/showthread.p...2917#post32917

Though the matching transformer at the antenna may offer a high resistance between the balanced input and unbalanced output, the breakdown rating of the insulating material is certainly not sufficient to stop a moderate static charge. Virtually all modern televisions employ power supply designs that provide isolation between the AC line and the chassis, but the amount of insulation used only provides safe isolation of normal power line voltages, not the high voltages that result from atmospheric activity.

If someone plugs their nice new TV into the wall, then mounts an antenna on their roof, runs the coax through the most convenient opening and then connects it to the TV, whats going to happen? In the vast majority of cases, the TV will work... for years. But for a few unlucky folks, unexpectedly, the TV just quits, because a small arc inside the tuner fried some bit of electronics (cost: repair or replace the TV). For an extremely unlucky few, a more spectacular event... perhaps a significant portion of a lighting bolt accepts the open invite to follow the coax into and through their home (cost: ????).

My point is that by choosing to run the coax from an outside antenna, the choice has been made to ground the antenna. That leaves one to consider whether it is worth spending a few dollars and maybe choosing a less convenient path for the coax run to dramatically reduce the risk of equipment damage and in a few very rare cases even protect against electrical shock or fire.
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Last edited by GroundUrMast; 24-Jan-2015 at 4:12 AM. Reason: Example citation/link, grounding / bonding
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