AVS Forum banner

1 - 20 of 160 Posts

·
Registered
Joined
·
43 Posts
Discussion Starter · #1 · (Edited)
I am attempting to cut the cord and got myself an Antennas Direct Clearstream 2 antenna. I also got a 10ft galvanized fence pole from Lowes and cut it down to 8ft to use as a mast. I mounted the antenna at the apex of my roof on the end side of the highest decorative eave post (I believe it's called an outlooker). Similar to the brown posts in this picture: http://www.fauxwoodbeams.com/blog/wp-content/uploads/2014/06/outlooker4.jpg. So my antenna is about 1ft away from the actual roof of the house.

Reception is great in my tests and now I am figuring out how I should ground everything. The coax cable runs to the box where I have a grounding block in there already in use for cable internet. This leads me to a couple of questions that I hope somebody can answer:

1. I'm looking to get a dual grounding block to share between the cable internet (which uses the single grounding block already there that came with the house) and the antenna. Any concerns with doing this?

2. I noticed that dual grounding blocks have two ground connections. Would I need to connect both grounds on the block?

3. Is it even necessary to ground my puny antenna and mast? I have a single story house and the top of my antenna is at the roofline height of my neighbors two-story house 20ft away. We get maybe one mild thunderstorm a year (bay area California). In my (naiive) mind I picture lighting striking the antenna and the decorative outlooker just falling off with the antenna and not causing major damage to the house.

4. If I must ground the antenna mast, can I run a ground wire along with the coax line into the same ground block that the coax/cable internet uses? That's the closest pre-existing ground source and is about a 50ft run.

Thanks in advance.
 

·
Registered
Joined
·
3,993 Posts
1. I'm looking to get a dual grounding block to share between the cable internet (which uses the single grounding block already there that came with the house) and the antenna. Any concerns with doing this?
No concerns

2. I noticed that dual grounding blocks have two ground connections. Would I need to connect both grounds on the block?
You wouldn't necessarily need to. Back when I used to be current on the details of the code, it said that the coax grounding conductor had to be approximately equal in current carrying capability to the coax cable outer conductors it was grounding, but in no case could it be less than 14 gauge. Cable companies commonly used 12 gauge solid to ground one RG-6 coax. But when a block is used to ground two coax cables, they have collectively twice the current carrying capability as one, so you would theoretically need twice the current carrying capability of your ground connection wire or wires to satisfy that, and that capacity is most easily met by running two ground wires. Alternatively, you could use one six gauge ground wire, but that is more difficult to obtain. Similarly, the big blocks that simultaneously ground four coaxes commonly have four ground wire attachment holes.

3. Is it even necessary to ground my puny antenna and mast? I have a single story house and the top of my antenna is at the roofline height of my neighbors two-story house 20ft away. We get maybe one mild thunderstorm a year (bay area California).
Not really. Grounds specified by the NEC are for safety purposes. In an antenna system, they theoretically tend to drain off static charge from an antenna that supposedly would otherwise make it more inviting to lightning, and the coax outer conductor ground is supposed to better assure that voltage that is on that outer shield it shunted to ground, rather than entering the house, where it could be a shock or fire hazard. I believe that coax ground is more useful in grounding the kind of voltage that might be incurred if a loose power line made contact with your antenna system.

There are no grounding police to find and penalize a nonconforming grounded antenna system. So-called installation professionals usually ground in accordance with code so that they will not be subsequently penalized by their employer for not having done so.

4. If I must ground the antenna mast, can I run a ground wire along with the coax line into the same ground block that the coax/cable internet uses? That's the closest pre-existing ground source and is about a 50ft run.
We all do that. Under some real rigid interpretations of the code, that might flunk the principles that the mast ground be as short and direct as possible, or that it not go laterally more than some specified distance without first being connected to its own 8' earth ground rod,, but frankly, that is one aspect of grounding code compliance that even the most finicky of installers choose to ignore. You can get coax that has 17 gauge copper clad steel ground wire attached to it and have that mast ground wire go into one hole of your "Siamese" ground block, and use the other ground wire hole for your earth ground and your antenna installation will be grounded as well as about 99% of all antenna installations
 

·
Super Moderator
Joined
·
18,459 Posts
Going to stick this since it comes up a lot. Thread is open and all additional advice is welcome so we have a rough FAQ.
 

·
Registered
Joined
·
43 Posts
Discussion Starter · #4 ·
Thank you Mike for the detailed explanation and the peace of mind. I went ahead and ordered a dual ground block (Holland GRB-2THR-UL) and a coax cable with a 17awg copper ground attached to it (http://prowirecommunications.com/store/product3.html). I had trouble finding a name-brand cable that offered less than 1000ft rolls of this stuff. Since it's an outdoor run, I can easily replace it if it fails.

In summary, I'll have three grounds routing through the ground block:
1. The coax cable from the street that provides cable internet
2. The coax cable from the antenna that provides OTA channels
3. The ground wire attached to the antenna coax which fastens to the antenna mast

One other thing I forgot to mention is that I have a small signal amplifier/splitter for the antenna in the same area as the ground block (http://www.amazon.com/Digital-Ampli...ibution+Cable+TV+HDTV+Splitter+Signal+Booster). If I connect this after the ground block, do I still need to ground it? In terms of grounding (or not grounding), where would be the optimal place for the amplifier?

Thanks again!
 

·
Registered
Joined
·
3,993 Posts
...I have a small signal amplifier/splitter for the antenna in the same area as the ground block (http://www.amazon.com/Digital-Ampli...ibution+Cable+TV+HDTV+Splitter+Signal+Booster). If I connect this after the ground block, do I still need to ground it? In terms of grounding (or not grounding), where would be the optimal place for the amplifier?
If that amplifier is located indoors, then it definitely doesn't need to be grounded. If it is outdoors, then it does raise the fuzzy issue of what it means to ground each coax as near as possible to the point where it(they) enter(s) the building.

It seems that the satellite TV installation companies have concluded to their own satisfaction that when their similar multiport amplification and switching devices are located outside the house but are grounded, that grounded case serves the same purpose as a grounding block.
 

·
Registered
Joined
·
113 Posts
It seems that the satellite TV installation companies have concluded to their own satisfaction that when their similar amplification and switching devices are located outside the house but are grounded, that grounded case serves the same purpose as a grounding block.
many are UL listed for that very purpose, but it sounds like he has the option to put it after the ground block in which case it does not need to be grounded. I prefer using proper ground blocks.. just for the permanence of them. then any changes are done instead with patch cables at the cost of -1dB.

I had a chance to discuss this with an electrical engineer but it got kinda iffy because they might not be that familiar with the anatomy of the antenna. In my case I was switching him from Directv to Dish and I was not the original Directv installer. There was no ground wire attached to the dish and the splitter at the home run was grounded. The debate was whether or not that was sufficient. In reality it doesn't matter much since the odds of lightning in his case were negligible, so if I was going to ground at all, I would ground it properly. An important physical difference between a D* dish and a E* dish is that the LNB is clamped directly to the dish itself, while E* dishes attach the LNB using a plastic bracket thus isolating the coax ground from the actual dish. I ran new cable to the dish with a messenger ground wire that was grounded at the service entrance outside rather than the main grounding electrode at the breaker panel.

I think professional installers are more often proponents of grounding than skeptics, but you'd probably know if you were at high risk of lightning based on the storms you've observed in the past. If you end up grounding it, then just keep the ground wire shorter than the coax run and just like AntAltMike suggested, use a #17 copper clad messenger wire. It's what the pros are using.
 

·
Registered
Joined
·
3,993 Posts
many are UL listed for that very purpose, but it sounds like he has the option to put it after the ground block in which case it does not need to be grounded. I prefer using proper ground blocks.. just for the permanence of them. then any changes are done instead with patch cables at the cost of -1dB.
But the thing is, "the code" requires the coax downleads to be grounded as near as possible to the point at which they enter the house, so whether the coax gets to a grounded distribution splitter or switch, there is still some distance from those output ports to the point at which each enters the house. This is one of many fuzzy issues regarding code grounding requirement definitions, namely, are the coaxes that go from an external, multiport amplifier or splitter or SWM unit actually antenna leads? Last time I checked, the code did not explicitly say, but I haven't really scrutinized the two most recent revisions.

I had a chance to discuss this with an electrical engineer but it got kinda iffy because they might not be that familiar with the anatomy of the antenna. In my case I was switching him from Directv to Dish and I was not the original Directv installer. There was no ground wire attached to the dish and the splitter at the home run was grounded. The debate was whether or not that was sufficient. In reality it doesn't matter much since the odds of lightning in his case were negligible, so if I was going to ground at all, I would ground it properly. An important physical difference between a D* dish and a E* dish is that the LNB is clamped directly to the dish itself, while E* dishes attach the LNB using a plastic bracket thus isolating the coax ground from the actual dish.
One point I keep making here, if for no other reason than that a lot of grounding commentary gradually gets buried, is that there are several different reasons that one grounds antenna systems. One is that doing so is supposed to enhance fire and shock safety, another is to attempt to protect consumer electronic equipment from surge damage, and a third, but the most important to so-called installation professionals, is so that they will not be penalized by their employer for not having installed in compliance with code when they were paid to do so. And many have expressed the concern here that their insurance requires it.

While I understand your conclusion that an LNB whose flange physically contacts a dish theoretically develops a conductive path from the mast to the coax outer shield, that does not satisfy the explicit mandate of the code and therefore a DirecTV or DISH Network system installer is not supposed to satisfy the grounding requirement that way. Furthermore, since the LNB support tube has a painted surface, it would not meet any accepted practice standards for attaching a ground wire or completing a ground path because its conductivity would be suspect.

Insofar as insurance liability is concerned, in the decade and a half in which I have participated in thousands of discussions on grounding, I have never once received a credible, verifiable report of an insurance company either refusing to pay a claim or using its subrogation right to sue an installer for recoup of any insurance payment it has made to an insured customer who had incurred damage to their improperly grounded antenna system.
 

·
Registered
Joined
·
113 Posts
But the thing is, "the code" requires the coax downleads to be grounded as near as possible to the point at which they enter the house, so whether the coax gets to a grounded distribution splitter or switch, there is still some distance from those output ports to the point at which each enters the house. This is one of many fuuzzy issues regarding code grounding requirement definitions, namely, are the coaxes that go from an external, multiport amplifier or splitter or SWM unit actually antenna leads? Last time I checked, the code did not explicitly say, but I haven't really scrutinized the two most recent revisions.



One point I keep making here, if for no other reason than that a lot of grounding commentary gradually gets buried, is that there are several different reasons that one grounds antenna systems. One is that doing so is supposed to assure fire and shock safety, another is to attempt to protect consumer electronic equipment from surge damage, and a third, but the most important to so-called installation professionals, is so that they will not be penalized by their employer for not having installed in compliance with code when they were paid to do so. And many have expressed the concern here that their insurance requires it.

While I understand your conclusion that an LNB whose flange physically contacts a dish theoretically develops a conductive path from the mast to the coax outer shield, that does not satisfy the explicit mandate of the code and therefore a DirecTV or DISH Network system installer is not supposed to satisfy the grounding requirement that way. Furthermore, since the LNB support tube has a painted surface, it would not meet any accepted practice standards for attaching a ground wire or completing a ground path because its conductivity would be suspect.

Insofar as insurance liability is concerned, in the decade and a half in which I have participated in thousands of discussions on grounding, I have never once received a credible, verifiable report of an insurance company either refusing to pay a claim or using its subrogation right to sue an installer for recoup of any insurance payment it has made to an insured customer who had incurred damage to their improperly grounded antenna system.
I read the satellite message boards too and most would say the same thing about employer requirements being the leading reason for grounding a dish, i.e. the threat of chargebacks. I get the impression (and correct me if I'm wrong) that regarding antennas you see grounding as unnecessarily prioritized by DIYers... Not that it's without value, just disproportionately emphasized. Along the same lines as things like buying special expensive tools to cut coax without squashing the dielectric, when all along they were going to strip off the squashed part regardless.

Anyway, your insight is extremely valuable and readers would do well to follow your advice.
 

·
Registered
Joined
·
159 Posts
Looking for advice on how/where to ground a rooftop antenna.

For a long time I've been wanting to hookup an old rooftop antenna to my dish network system. I have a 722K with an OTA Module. This gives me two extra tuners for ota only, which helps reduce timer conflicts. Since I didn't want to drill any extra holes in the walls to run the antenna cabling, I figured out(with some help) how to run it directly through the dish wiring with the use of splitters/diplexers. Works great.

I do want to ground the antenna but don't know how. The Dish system is already grounded(see photo below), I'm wondering if I can run a wire to the same grounding block? Or do I need to ground it separately? Any suggestions would be great. :)

The cabling at the bottom of the photo is from the antenna, which goes into the splitter then diplexer.
 

Attachments

·
Registered
Joined
·
159 Posts
Looking for advice on how/where to ground a rooftop antenna.

For a long time I've been wanting to hookup an old rooftop antenna to my dish network system. I have a 722K with an OTA Module. This gives me two extra tuners for ota only, which helps reduce timer conflicts. Since I didn't want to drill any extra holes in the walls to run the antenna cabling, I figured out(with some help) how to run it directly through the dish wiring with the use of splitters/diplexers. Works great.

I do want to ground the antenna but don't know how. The Dish system is already grounded(see photo below), I'm wondering if I can run a wire to the same grounding block? Or do I need to ground it separately? Any suggestions would be great. :)

The cabling at the bottom of the photo is from the antenna, which goes into the splitter then diplexer.
Bump :)
 

·
Registered
Joined
·
113 Posts
Just run 10 gauge solid copper from the antenna mast to the ground block and call it done. While you're up there you should replace those twist-on fittings with compression fittings to prevent water migration and inevitable corrosion. A cheaper alternative would be to find some 1/2" heat shrink tubing and hit it with a lighter but there are other problems with twist-on fittings besides moisture. I snip them off immediately whenever I see them. Also, it takes all of 10 seconds and a 3 cent zip tie to make that service loop into a neat circle. I hope you did that and not the technician. Yuck
 

·
Registered
Joined
·
254 Posts
Grounding outdoor antenna... where?

Hello everyone,


I recently bought a RCA ANT751R to get OTA television at our new place - and plan on mounting it on or near the roof (don't know if peak of roof of eaves in back of house is preferred location, I would imagine peak since it's directly above the breaker/meter and is about 5' higher but if anyone has differing opinions let me know), I've read the NEC code and bought all of the relevant supplies for the install, one big issue remains: I can't seem to find the main ground.


Our house doesn't appear to have a ground rod, I've tried digging for it and nothing is down there that I can see. Our house is built on a slab, so perhaps it's embedded in the concrete, or they used the water main - considering it's on the other side of the house I doubt that.


I've attached a photo of the service box/panel - they are combined into one unit so I imagine the ground is hiding in there somewhere. The stuff on either side is sprinkler/HVAC so ignore those.


I know NEC permits grounding to the service enclosure, which looks like it may be the best bet in this scenario short of having an electrician or the power company come out - which I would rather avoid.


Any feedback on this would be great.
 

Attachments

·
Registered
Joined
·
83 Posts
Start digging around the conduit for the Telephone NID with a hand shovel. You will find out if that ground wire connects to a Ufer ground, or goes to a ground rod. Do not get all gung ho and start slamming the shovel in the ground. Just take your time and loosen up the soil, then use your hand to move it aside.

Usually the ground wires are around 4"-6" under the soil.
 

·
Registered
Joined
·
254 Posts
The telephone and CATV conduits (black cables, really) are in PVC pipes that go down several inches. Keep digging?
 

·
Registered
Joined
·
598 Posts
Cable grounded directly to service panel

When my cable was installed, the installer just attached the green ground wire with a tag that says 'do not remove' directly to the service panel. They must know what they are doing, right.
 

·
Registered
Joined
·
113 Posts
Cheapest route would be simply use a corner clamp for a few bucks
https://www.google.com/search?q=gro...a=X&ei=m5VPVPHWHoqvyASupID4BQ&ved=0CAcQ_AUoAg

If the electrical service conduit is metal and not pvc you could use a strap, that's pretty cheap too
http://www.alliedboltinc.com/productimages/Premium Ground Strap-Galvanized 24GAB.jpg

Usually inside the cable co. enclosure (2nd from bottom) there should be a ground block with a wire going to a ground source. It'll be the only wire coming out of that box that's not coax. I wouldn't recommend this but if you could flip the breaker for that receptacle and get a ground wire in there you could pigtail off of that ground. If all else fails, hire an electrician to add a grounding busbar below the meter and ground whatever you want to it.
 

·
Super Moderator
Joined
·
18,459 Posts
Please use existing threads before starting a new one. Threads merged.
 

·
Registered
Joined
·
254 Posts
Cheapest route would be simply use a corner clamp for a few bucks
https://www.google.com/search?q=gro...a=X&ei=m5VPVPHWHoqvyASupID4BQ&ved=0CAcQ_AUoAg

If the electrical service conduit is metal and not pvc you could use a strap, that's pretty cheap too
http://www.alliedboltinc.com/productimages/Premium Ground Strap-Galvanized 24GAB.jpg

Usually inside the cable co. enclosure (2nd from bottom) there should be a ground block with a wire going to a ground source. It'll be the only wire coming out of that box that's not coax. I wouldn't recommend this but if you could flip the breaker for that receptacle and get a ground wire in there you could pigtail off of that ground. If all else fails, hire an electrician to add a grounding busbar below the meter and ground whatever you want to it.
Ground wire in the CATV box (green) goes inside the wall. Which leads me to think I have some weird ufer ground integrated into the slab foundation. Corner clamp it is.
 

·
Registered
Joined
·
181 Posts
Really stupid question I realize. But exposing my ignorance, newbiness here. All of this talk of grounding, is this for lightning protection?

I am not totally satisfied with my in-attic antenna for OTA reception and am therefor considering going to a roof one. As we live in an are prone to a lot of storms, especially in the April/May time of the year, I want to protect my system from lightning strikes. Is grounding the outdoor antenna going to be sufficient to do so? I would think that I would need some sort of in-line surge protector.
 

·
Registered
Joined
·
3,993 Posts
... All of this talk of grounding, is this for lightning protection?
The talk is for whomever spaketh. Grounding the mast is intended to make it a less inviting target to lightning and to shunt as much of the lightning energy as possible to ground. Grounding the coax cable as near as possible to the point at which it enters the building sdimilarly shunts dangerous current to ground. The standards for each have been determined under the model National Electric Code, or NEC, to be recommended and often mandated procedures for minimizing the fire and shock hazards that external antennas create.

I want to protect my system from lightning strikes. Is grounding the outdoor antenna going to be sufficient to do so? I would think that I would need some sort of in-line surge protector.
Protecting your system from damage from lightning strikes is an incidental benefit to grounding it for fire and shock prevention, but such grounding can never be wholly adequate for that purpose, because it just doesn't take much of a "zap" to damage semi-conductors in consumer electronic products, so you can still additionally benefit from adding surge protection devices into an otherwise grounded antenna signal path.
 
1 - 20 of 160 Posts
Top