Need to Ground an Attic Antenna? - AVS Forum
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post #1 of 25 Old 04-05-2008, 02:25 PM - Thread Starter
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Great OTA reception with an attic antenna (no amp), but I'm sure a lighning strike near my HDTV would ruin my day. Power to HDTV is surge-protected, but not sure if I should be grounding my attic antenna by attaching the shield of its coax lead-in (about 75 ft) to a local waterpipe. Alternatively, my surge protector at the HDTV has in/out coax connectors "for CATV". Is this of value in my case?

Any advice most welcome.
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post #2 of 25 Old 04-05-2008, 06:45 PM
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Not really needed in an attic install. Outdoor antennas need to be grounded because they pick up a static electricity charge when the wind blows across them. That charge then can help attract lightening if it's not discharged via a ground.

On a side note, regardless how well grounded or surge protected your antenna is, if it took a direct hit it's gonna make it to your electronics.

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Please don't PM me with technical questions that should be posted in the forum.
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post #3 of 25 Old 03-09-2009, 06:40 AM
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Digging up an old topic to continue the discussion. I would also think grounding your attic antenna for lightning would increase the probability your house would be struck by lightning and start it on fire. Is this legitimate thinking?

Scott
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post #4 of 25 Old 03-09-2009, 06:46 AM
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Quote:
Originally Posted by scottlindner View Post

I would also think grounding your attic antenna for lightning would increase the probability your house would be struck by lightning and start it on fire. Is this legitimate thinking?

No. Don't take that rule about "the shortest path to ground" too literally. Besides, your house is full of wires at ground potential; one more would make no difference.
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post #5 of 25 Old 03-09-2009, 07:39 AM
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Quote:
Originally Posted by scottlindner View Post

Digging up an old topic to continue the discussion. I would also think grounding your attic antenna for lightning would increase the probability your house would be struck by lightning and start it on fire. Is this legitimate thinking?

Scott

will not make a difference. lightning has just traveled through miles of air (which is a good insulator) so a little more conductive path for 20 feet is not going to make any difference. also the amount of current seeking ground potential at that high voltage is huge, so lightning bolts split near the earth surface, wood such as your house or trees are as good a path as a small wire.

grounding does provide a sink for induced currents from any nearby (within a few miles) lightning strike which is a useful thing. just as an indoor antenna will diminish your tv signal so induced currents might be diminished.

an outdoor antenna should be grounded to a grounding rod outside your home before the cable comes into your house. because your antenna and cable are already inside you wouldn't use a grounding rod outside but could use a good electrical ground inside. also a grounding block only protects the coax shield (connected to only part of your antenna) you need a coax lightning arrestor to also protect the center conductor. best protect for your equipment is to disconnect your antenna (especially outdoor) during a thunderstorm.
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post #6 of 25 Old 03-09-2009, 08:27 AM
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Quote:
Originally Posted by gerryp123 View Post

Great OTA reception with an attic antenna (no amp), but I'm sure a lighning strike near my HDTV would ruin my day. Power to HDTV is surge-protected, but not sure if I should be grounding my attic antenna by attaching the shield of its coax lead-in (about 75 ft) to a local waterpipe. Alternatively, my surge protector at the HDTV has in/out coax connectors "for CATV". Is this of value in my case?

Any advice most welcome.

No lightning danger, but most AV devices have two wire ungrounded plugs. Unless you are certain that everyone who will ever play with the connections is going to unplug EVERYTHING first, a ground can be a good thing.
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post #7 of 25 Old 03-09-2009, 11:25 AM
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For lightning protection, no.

It may provide some marginal benefit for reception, however. If you don't have any marginal channels, it probably isn't worth the effort.
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post #8 of 25 Old 03-09-2009, 11:51 AM
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Hey Meow,

How marginal is "marginal"? My weakest station has a margin to dropout that varies between 10 and 17 dB. I measured margin to dropout by adding pad attenuators until pixelation or video dropout. My attic antenna is not grounded. Will grounding help this weaker station?

Thanks

Rick
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post #9 of 25 Old 03-09-2009, 03:59 PM
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Quote:
Originally Posted by nybbler View Post

No. Don't take that rule about "the shortest path to ground" too literally. Besides, your house is full of wires at ground potential; one more would make no difference.

It is shortest electrical path, not physical and copper has an extremely low impedance.

Scott
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post #10 of 25 Old 03-09-2009, 04:08 PM
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The reason I ask is I live in a high lightning area. My neighbor's home was hit two years ago. Thankfully his home didn't burn, but every last electronic in his home was fried. Even the microwave and alarm clocks. Nothing survived that was digital. So this is something I'm concerned about, but I'd much rather loose my electronics than loose my home to fire. I do understand that my home is already filled with conductors so maybe it's such a trivial additional to the potential of a lightning strike, but still, if I take a hit to the home, my electronics are the least of my concerns. I do have surge supressors of some form on all major electronics including the antennas (integrated with line conditioners).

Is there a best practice that we can consult or building codes? What do the professionals do in this situation?

Scott
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post #11 of 25 Old 03-09-2009, 04:18 PM
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Scott,

check this url : http://www.hdtvprimer.com/ANTENNAS/basics.html

scroll down some and there is good discussion on grounding
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post #12 of 25 Old 03-09-2009, 04:25 PM
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Quote:
Originally Posted by IDRick View Post

Scott,

check this url : http://www.hdtvprimer.com/ANTENNAS/basics.html

scroll down some and there is good discussion on grounding

That's an excellent link. Thank you! Here's the relevant text;
Quote:


Indoor antennas (including attic antennas) are not generally susceptible to direct strikes. In such cases a grounding block is not required by the rules, but is probably a good idea when the cable is longer than 30 feet.

My coaxial cable length is more like 50ft. I would like to understand more of the basis for the comment "probably a good idea". That is subjective without any evidence or argument. Understanding the basis of why they said this would help me understand my situation better. Also, this article states that indoor grounding rods are in dry soil so they conduct very little. I was thinking about placing a grounding rod indoors but this changed my mind.

Scott
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post #13 of 25 Old 03-09-2009, 06:11 PM
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Quote:
Originally Posted by scottlindner View Post

The reason I ask is I live in a high lightning area. My neighbor's home was hit two years ago. Thankfully his home didn't burn, but every last electronic in his home was fried. Even the microwave and alarm clocks. Nothing survived that was digital. So this is something I'm concerned about, but I'd much rather loose my electronics than loose my home to fire. I do understand that my home is already filled with conductors so maybe it's such a trivial additional to the potential of a lightning strike, but still, if I take a hit to the home, my electronics are the least of my concerns. I do have surge supressors of some form on all major electronics including the antennas (integrated with line conditioners).

Is there a best practice that we can consult or building codes? What do the professionals do in this situation?

Scott

in a high lightning area best practice is to unplug from antenna any time you hear thunder. also unplug your phone and any electronics you care about.

keep a less expensive tv and radio connected for news and weather during storms. have a single cordless phone plugged in not on the charging base to use phone during storm.
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post #14 of 25 Old 03-09-2009, 08:43 PM
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Quote:
Originally Posted by gerryp123 View Post

I'm sure a lightning strike near my HDTV would ruin my day.

It would.

A nearby lightning strike can induce voltage inside your house even without hitting it directly. It's an inductive effect that I've seen myself. I was standing about 100' away from a 700' tower when a lightning strike hit about a mile away. There was a simultaneous secondary flash that extended about 50' above the top of the tower.

Think of it as a transformer. The lightning is the primary. The air is the magnetic core. Your lead-in is the secondary.

That's not the only reason.

In New York Verizon is being required to ground a FiOS fiber to coax converter inside the house, even though lightning can't follow the glass fiber. The Public Service Commission feels that a grounded coax might protect you from electrocution if the TV set were to have an internal short.
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post #15 of 25 Old 03-09-2009, 11:25 PM
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Quote:
Originally Posted by scottlindner View Post

The reason I ask is I live in a high lightning area. My neighbor's home was hit two years ago.

Will even EMP-hardened military gear survive a direct hit by lightning?

Ride the Music
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post #16 of 25 Old 03-09-2009, 11:51 PM
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Originally Posted by johnpost View Post

keep a less expensive tv and radio connected for news and weather during storms.

We have a small portable TV that can run off of 12 volts for emergencies.
It can pick up a few local analog stations with the built-in rabbit ear.
What is the digital equivalent?

Is there any portable with a really good ATSC tuner?

Ride the Music
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post #17 of 25 Old 03-10-2009, 06:32 AM
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Originally Posted by andytiedye View Post

We have a small portable TV that can run off of 12 volts for emergencies.
It can pick up a few local analog stations with the built-in rabbit ear.
What is the digital equivalent?

Is there any portable with a really good ATSC tuner?

there seem to be more ATSC portables showing on the market now, 5 and 7 inch LCD sets with DC power and internal/external antennas. ones I've seen had good tuners. check your usual department store and other vendors.
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post #18 of 25 Old 03-10-2009, 04:13 PM
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Quote:
Originally Posted by andytiedye View Post

Will even EMP-hardened military gear survive a direct hit by lightning?

What does that have to do with trying to avoid lightning strikes? I'm not attempting to hang up my HDTV on the roof of my house and kick back with lawn chairs to get the great view up there during an electrical storm. Although the view would be fantastic from up there.

Scott
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post #19 of 25 Old 03-10-2009, 07:24 PM
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Quote:
Originally Posted by IDRick View Post

My weakest station has a margin to dropout that varies between 10 and 17 dB.

That's not really marginal at all. Or, perhaps more precisely, that's beyond marginal, and is in fact a signal you can only get under the right weather conditions.

A really hardcore effort to tighten down every aspect of an antenna rig might be able to buy you an additional 5 db of signal tops. And when I say that, I'm talking adding the lowest noise preamp possible, along with perfect grounding, RG-11 coax.

Short of moving the antenna to the roof, you're not going to get much more signal.
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post #20 of 25 Old 03-11-2009, 09:17 PM
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Quote:
Originally Posted by MeowMeow View Post

That's not really marginal at all. Or, perhaps more precisely, that's beyond marginal, and is in fact a signal you can only get under the right weather conditions.

A really hardcore effort to tighten down every aspect of an antenna rig might be able to buy you an additional 5 db of signal tops. And when I say that, I'm talking adding the lowest noise preamp possible, along with perfect grounding, RG-11 coax.

Short of moving the antenna to the roof, you're not going to get much more signal.

Hmmm, I am giving you the actual margin to dropout, not NM from tvfool. Channel has come in well under all weather conditions. I have yet to lose signal on this channel. HDP 269 would appear to be a good pre-amp choice in my location. I have conducted a single test on the roof, not the easiest with snow. There was a slight gain in margin to dropout (~2 to 4dB, depending on the station). With my test rig, I'm using 35 ft of rg59 on the roof. There will be some improvement in margin with rg6 when I finalize installation.
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post #21 of 25 Old 03-11-2009, 09:36 PM
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Quote:
Originally Posted by IDRick View Post

Hmmm, I am giving you the actual margin to dropout, not NM from tvfool. Channel has come in well under all weather conditions. I have yet to lose signal on this channel. HDP 269 would appear to be a good pre-amp choice in my location. I have conducted a single test on the roof, not the easiest with snow. There was a slight gain in margin to dropout (~2 to 4dB, depending on the station). With my test rig, I'm using 35 ft of rg59 on the roof. There will be some improvement in margin with rg6 when I finalize installation.

OK, I didn't completely understand you. So, you're saying under the worst conditions the channel still is about 10 db higher than needed. Fair enough.

RG6 will make a difference, especially over any decent length run of wire.

I'm an advocate of properly grounding all antennas. In my experience, which is at the low end of deep fringe (60 mi from most transmitters I want), I've seen grounding bring in channels that were just ever so close to coming in solid.
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post #22 of 25 Old 03-12-2009, 05:59 AM
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Quote:
Originally Posted by MeowMeow View Post

OK, I didn't completely understand you. So, you're saying under the worst conditions the channel still is about 10 db higher than needed. Fair enough.

RG6 will make a difference, especially over any decent length run of wire.

I'm an advocate of properly grounding all antennas. In my experience, which is at the low end of deep fringe (60 mi from most transmitters I want), I've seen grounding bring in channels that were just ever so close to coming in solid.

What size grounding wire? Is it legit to use an intermediary grounding block to break out to multiple antennas and to provide grounds to other devices before heading on to the grounding stake? I'm having a hard time finding this information online.

Scott
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post #23 of 25 Old 03-17-2012, 05:06 PM
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Hi .
I have a question .
I bought a cheap 8bay hd tv antenna on ebay

Yesterday there was a big lightning and I thought it hit my antenna . So I was really scared and I want to know if I need to ground my antenna .
My antenna is 3 feet higher than the top of my house . I thought those antenna was made of alluminium .

Should I ground my antenna even if I got only 9 channels ?


Thank you
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post #24 of 25 Old 03-18-2012, 07:17 AM
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Quote:
Originally Posted by skydroz View Post

Hi .
I have a question .
I bought a cheap 8bay hd tv antenna on ebay

Yesterday there was a big lightning and I thought it hit my antenna . So I was really scared and I want to know if I need to ground my antenna .
My antenna is 3 feet higher than the top of my house . I thought those antenna was made of alluminium .

Should I ground my antenna even if I got only 9 channels ?


Thank you

It does not matter how many channels you get. If the antenna is mounted outdoors, it needs to be grounded.

SMK
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post #25 of 25 Old 03-18-2012, 07:34 AM
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Quote:
Originally Posted by scottlindner View Post

What does that have to do with trying to avoid lightning strikes? I'm not attempting to hang up my HDTV on the roof of my house and kick back with lawn chairs to get the great view up there during an electrical storm. Although the view would be fantastic from up there.

Scott

Oh, I wish we could get some of our "mountain" engineers in on this .
They live inside of a metal-roofed building, with about a dozen huge towers around them, about 9500 feet above sea level, and about a mile above the city.
Basically, the whole top of the mountain is laced with ground rods and copper straps. Each tower is grounded, as well as tied to all the other grounds.
Every antenna is tied to the tower ground, and all transmission lines are grounded where they enter the buildings.
They have a fantastic view of storms from all directions.

Ken English, Sr. Engineer, KSL-TV.
"The postings on this site are my own and don't necessarily represent the Company positions, strategies or opinions."
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