CurtPalme.com Home Theater Forum

ecrabb

Guys,

I'm moving a satellite dish (I installed it) from a temp ground mount (been there for 4 years - so much for temporary) to the roof of the garage, along with a new OTA antenna. Including the drop from the roof, it'll probably be a 50-60' run from the new location to the point of entry on the house. I'm confused about what I should or shouldn't do with the ground.

I was thinking that where the run drops off the roof of the garage, I'd put in a new grounding rod, and run a #10 from the antenna and dish. From there, I'd bond that the rod and the house's main ground with a 30' piece of #6 so I wouldn't have a floating ground. That OK?

The point of entry is right next to the house ground rod, so I can ground the ground blocks right there with a short piece of #10.

I know I probably don't even need the new ground rod, but I think the NEC says ~25 feet for a #10 ground, and I'll be at 50 or 60.

Am I on the right track?

SC

jkruger · Joined: 24 Oct 2007 Posts: 2435 Location: Carlsbad, CA

That looks like the right way to do it. I would do the same.

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

I'm not sure I would put a new ground rod in that far away from the "house/master" ground rod. Why not just run #10 to the house ground? It also wouldn't hurt to drive another ground rod right next to the house ground rod.

Do not under estimate the power of good grounding.....

wallace

ecrabb · Posted: Fri Nov 07, 2008 2:57 am Post subject:

I was actually going to do it that way, Don. But, then I read somewhere that the NEC says 25' max on #10. I assume I could go larger (#6), but then I'm running 60' of #6 ($$) AND I'm taking the high current from a lighting strike right back to the main house ground rod - which you know will go back into the house.

Now, I know ground rods aren't for lightning protection... and if I take a direct hit, it's probably going to fry everything anyway... Still, I feel like it would be better and safer having a drain nearer the antennas. Question

SC

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

My dish is grounded with a very thin wire that is part of the coax cable(on the outer jacket) And my roof its mounted on is at least 35 feet up, then its just grounded inside to the main Panel Box along with the Sat distribution block.

Athanasios

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

IMO, the only thing ground rods and grounding is good for is to prevent ground loops and possibly to help if there is a near-by lightning strike.

I am sure the NEC standard is there for a good reason, but for my thought of preventing ground loops (difference of potential), the #10 bare ground wire would suffice.

Again, my thought is that if lightning strikes (direct hit) ain't nothing going to help; everything is toast. Thumbs Down

If you look at commercial buildings (my experience is with buildings built for telephone central offices), they have ground grids that are massive is size. And yes, they do tie a lot of stuff together at a common point. But they do spend a lot of bucks on wire size (gauge) to make this happen.

wallace

ecrabb · Posted: Fri Nov 07, 2008 4:30 am Post subject:

Good points, and I agree. Thinking about it more, I should throw the lightning issue aside. Grounding has nothing to do with lighting and if there is a direct hit, as we both mentioned - everything is toast. If we accept that the grounding has nothing to do with lightning and everything to do with static, the lighter gauge (#10) - even stranded copper - is probably just fine.

Thinking about it some more from a lightning perspective, the lighter-gauge wire is probably better, because it's more apt to just blow apart instead of actually carrying a lot of current back to the ground.

The NEC req is kind of goofy. If grounding is all about static, how much resistance can even 100' of 10 ga wire present? Certainly not enough to retard static drain?!?!?! I don't get that.

I went ahead and posted this question to dbstalk, too to see what those guys had to say. Maybe one of them can shed some light on the NEC req.

SC

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

Good question, standard practice around here is not to set the dish as a high point on the structure and to use a grounding block and drip loop.

Now you have me worried...

good link here: http://www.sadoun.com/Sat/Installation/Grounding.htm

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

I have 2 dishes and neither one is grounded and I have now problems. Using ground rods could give you ground loop problems because of the difference in potentials between the grounding points.

**Curt Palme** · Posted: Fri Nov 07, 2008 3:01 pm Post subject:

THIS is how you ground a satellite dish. Very Happy

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

Where's the Russian Spy Trawler those came from? Laughing

BTW-Nice house SC Thumbs Up

ecrabb · Posted: Fri Nov 07, 2008 4:56 pm Post subject:

Thanks for the link, Jask. That helps... I know I absolutely have to ground the coax right at entry - those will go to main house ground right at the service entrance. The question is whether to ground the dish and antenna where it drops off the roof to a new grounding rod (also bonded to the main ground to eliminate a floating ground/ground loop), or whether to run the ground from both all the way back to the main. I'm still not clear on what's best and the guys at DBStalk have nothing to offer so far. 60-some views and no reply to my question!

Walter, I know it would could great a ground loop if they were separate, but the plan was that if I used a second ground, they would be bonded together, which should hold them at same potential.

Thanks, Greg... Too bad you can barely see it!!!

SC

ecrabb · Posted: Fri Nov 07, 2008 4:59 pm Post subject:

Oh, get this... Talk about coincidence... Part of this thread is lightning-related, right? Well, I'm the pres of the HOA we live in... I just got an email from a fellow resident, that her house was hit by lightning Wednesday morning at 4:45. Not surprisingly, my wife and I both shot up in bed (my wife even screamed a little) when that lighting bolt hit. It was like a damn bomb going off. It was F'ing LOUD. I knew it was a really close hit, both from sound (obviously), but also that it tripped the arc fault breaker for our master bedroom. Wow!

SO, how do those things work? I mean, I know there was BIG DAMN ARC nearby alright, but how does it work?

I'll be at her house to snap a few pics this weekend and I'll post them here. Apparently, it blew out some drywall, busted open a gas line in the wall (THAT'S not scary at all!), scorched some wiring in the wall, and fried a bunch of electrical stuff in the house. Her teenage son heard the gas line hissing and they called the utility to come shut off her gas.

That's some scary sh*t, eh?

SC

**AnalogRocks** · Posted: Fri Nov 07, 2008 5:20 pm Post subject:

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

My neighbors house a stones throw away got hit by lighting. The owner walked around the house but didn't see anything so went to bed. At around 2:30am the ceiling over their heads in the master BR burst down in a shower of flame and sparks...about 6 ft from their bed. Shocked

Evidently the lightning blew a hole about as big as a golfball through the roof and started the insulation smoldering. The house was a total loss by the time the cellar savers, erm, fire dept got there.

My wife and I were out on our deck where we could see the house over our stockade fence and my 12 year old son came out and loudly exclaimed "OH COOL! A FIRE!!!" The crying family was RIGHT on the other side of the fence when he said it. Embarassed

AFCI info in laymens terms:
http://www.mikeholt.com/mojonewsarchive/AFCI-HTML/HTML/AFCI_Questions_and_Answers~20030301.htm

From another source:
"The AFCI has an electronic circuit in it that monitors the waveform of the electricity flowing in the circuit and when an arc occurs it distorts the waveform and the breaker is tripped." Which may explain how an indirect lightning hit could trip an AFCI via EMP like waves???

One last thing:
‘Important Product Recall Information: Arc Fault Circuit Breakers manufactured by Square D Corporation’
Square D Corporation has issued a product recall for Arc Fault Circuit Breakers, which were manufactured between
March 1, 2004 and September 23, 2004. Although these breakers may not sense an arc, the short-circuit
and overcurrent protection continue to function properly as per Square D.

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

I was mentioning this to a friend today and he looked at me like I was retarded and said "That would make it a ground path,why would you want to incorporate a lightning rod into your A/V system?"
tough to argue with logic...

**AnalogRocks** · Posted: Sat Nov 08, 2008 5:55 am Post subject:

What about one of those "Spark Gap" devices where you screw the incoming coax in one side, it has the #10 wire running to a ground rodthen the coax out the other side.

ecrabb · Posted: Sat Nov 08, 2008 6:56 am Post subject:

Jeremy, that's called a ground block - and I'll be using those - that's how you ground the coax shield on every drop.

Jask, what the friend doesn't seem to understand is that the antenna or dish is ALREADY grounded... via your TV or sat receiver inside your house! So, it's a given that it's a lighting rod - that's the way it is. The question is, do you want to give the lightning one path to ground (through the equipment in your rack), or do you want to give it a low-resistance alternate path to ground OUTSIDE your house into a grounding rod stuck in the dirt? That's where the NEC comes in with the safety codes.

As has been pointed out, a direct lighting strike is probably going to fry anything and everything sensitive in your house. The question though, is do you just lose some equipment from overvoltage because most of the current went to ground outside? Or, do you have a fire in your theater or living room because a BUNCH of current went through the TV or Sat receiver.

SC