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HR20 Satellite Dish Antenna Grounding Requirements


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13 replies to this topic

#1 OFFLINE   Milominderbinder2

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Posted 09 May 2007 - 11:48 AM

Reasons to Properly Ground a Satellite Dish Antenna:
1. Safety
2. Manufacturer’s Warranty
3. Local Code and Ordinance.
4. Insurability
5. Proper Operation of Electronics

How Do I Know If My Dish Is Properly Grounded?
A qualified professional can review your installation including a proper "grounding block" as highlighted in yellow below:

http://www.dbstalk.c...=1&d=1178732807

A professional can verify that you have a correctly sized grounding wire (highlighted in green above) attached to the metal part of the antenna and the grounding block. He can also insure that the grounding wire is connected to an outside metal cold water pipe at point of entry, 8-foot ground rod, etc.... The diagram and text above is taken from the AT9/AU9 manuals. See your satellite dish manual for details. While the dish manuals show Option 2, the NEC never recommends daisy-chaining grounds. Also in Option 1, you should not combine ground taps on the cold water pipe.

Safety
Per FEMA, each year there are approximately 67,800 electrical fires that result in:
- $868 million in property damage.
- 2,305 injuries
- 485 deaths

Some electrical fires and shocks could have been prevented with proper grounding and wiring. A Ground Loop can occur when two points expected to both be the same potential (ground in this case) are at different voltages. Ground Loops can cause deadly currents.

Manufacturer’s Warranty
DIRECTV gives detailed instructions in the proper installation of a satellite dish antenna in the AU-9 Manual, AT-9 Manual, and AT-9 Installation Videos.

Local building and electrical codes (NEC) require the antenna and the coaxial cables to be connected to a grounding electrode. Improper installation may seriously damage the equipment or the building, as well as cause injury or death to you.

If you suspect your dish is not properly grounded, contact DIRECTV. Your home may not be properly grounded either.

Local Code and Ordinance
The 2005 National Electrical Code states in part:
Section 810.15 "Masts and metal structures supporting antennas shall be grounded in accordance with section 810.21"
Section 810.20 "Each conductor of an antenna lead-in shall be provided with a listed antenna discharge unit."

Failure to comply with the National Electrical Code may violate your state, county, and city laws. Check with your local building code officer. As a sample, here is the code for the State of Minnesota. The 2008 NEC is expected to strengthen five key areas including Grounding & Bonding.

Insurability
Your Homeowners Insurance Policy may cover damage due to electrical surge or lightning. But your policy under Section I – Losses Not Insured may exclude: “Latent defect of material or workmanship.”

Ask your insurance carrier if failing to follow manufacturer requirements or local code could affect future claims.

Proper Operation of Electronics
• Improper grounds may cause noisy signals. You may hear "hum" in your phone lines or through speakers.
• A Floating Ground can occur when an improper ground allows the voltage to float. It can cause lost data due to insufficient voltage differential.
• Lost data can cause video pixelation or Caller ID to not work.
• Using a surge suppressor does not correct the problems of an improper ground.

Disclaimers:
1. This is a simple overview that in no way represents the views of DIRECTV or DBSTalk. Refer to your owners manual, state, and local laws.
2. The information above is not warranted or guaranteed nor is it offered as recommendation or expert opinion. Trust nothing you see on the Internet.
3. Hire a qualified professional. Verify the dish and home wiring and grounding. Do not attempt dish installation without proper training.
4. Proper grounding does not prevent all lightning strikes. As NASA states, lightning can be up to 5 times hotter than the sun and up to 300,000 volts.

- Craig

With special thanks to Hasan, Brott, Tom Robertson, Coffey77, Lamontcranston, and Carl6.

Attached Thumbnails

  • AU9-AT9-GroundingDiagram.GIF


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#2 OFFLINE   Milominderbinder2

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Posted 09 May 2007 - 11:50 AM

held for future use.

- Craig

#3 OFFLINE   Groundhog45

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Posted 09 May 2007 - 12:01 PM

That document is well done. Thanks to Milo and the gang. I see that my ground isn't correct and I need to address it soon.

Richard -- DirecTV since '97
Team SETI.USA

 


#4 OFFLINE   n3ntj

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Posted 10 May 2007 - 02:29 PM

Excellent info and glad you referenced the NEC section 810. I am an electrical engineer and an inspector and your info is right on the mark. I would make a clarification, however, when referencing a cold water pipe.

As you mention, the cold water pipe has to be metal (of course!), but if the pipe is sticking out of the ground (in the yard, for example), to be used as an electrical ground, the metal pipe has to have 8~10 feet of continuous contact with the Earth. In other words, it can't stick out of the ground near the home and then go inside the home through the foundation. Like a ground rod, the water pipe needs to have more than 8' of continuous earth contact. If the home has all metal plumbing, there also needs to be a bypass at the water meter for continuity using a Cu or Al jumper.

Also, if the home's electrical service ground rod is to be used (which is recommended), it has to have a separate ground rod clamp for each conductor. You can't use the same ground rod clamp for two electrical grounding conductors (one from cable/sat., one from telephone, etc.).

If a separate ground rod is to be used for a satellite system, telephone system, etc., the new ground rod and the home's electrical service ground rod must be bonded together using at least a 8 AWG copper bonding wire. Not bonding the two ground rods can allow for voltage differences b/w the two ground rods. In Canada,
believe it or not, two ground rods for the electrical system is code.

Now, if we could just get the D* subcontractors (like Ironwood) to make installations to meet these requirements. I've seen many DSS installations that I believe Ironwood did (they are the local D* sub) and most are to PEX plumbing or no ground whatsoever. Is Ironwood (or D*) liable if an improperly installed satellite system were to lead to a house fire, injury, or death?

Good work!

Matt Steger
EE
HD Snob - "Friends Don't Let Friends Watch Cable".
Electrical/RF Engineer & Inspector
DirecTV Equipment: HR24-200, HR24-100, 5LNB Slimline, AM21, SWiM 8 installed (MRV)
HR-2x Configuration: Native OFF. Units OFF when not in use.
TVs: 2 Panasonic Plasma TV's each using HDMI (one 1080p/one 720p)
DirecTV customer since 1998. Plus HD DVR package w/ NHL Center Ice & MLB Extra Innings.
OTA Antenna: Homebrew UHF & VHF antennas w/ 30dB amplifier fed w/ RG-6 Quad-shield coax.

#5 OFFLINE   Diana C

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Posted 10 May 2007 - 04:36 PM

Looks great Craig. I would add that grounding is designed to protect the users' LIFE, not their equipment. I personally have seen a set top box literally blown across a room by the explosive discharge of a lightning strike carried into the home by the downlead. Had anyone been in the way, that box could have killed them, not to mention the fire and shock hazard.

I have also seen lots of satellite installers ground systems INSIDE the home, to an electrical box. This NOT acceptable. The point of the outside path to earth is that the ground wire, as the path of least resistance, will carry the lightning current to earth, and likely melt in the process. You do NOT want superheated wires melting inside your house.

Finally, your diagram assumes that the cold water pipe itself is grounded correctly. Users shoud check this since this may not always be the case. In these days of PVC piping, a pipe may or may not have electrical connectivity to the household ground point. Technically, there should be a ground rod installed as close as possible to the point where the coaxial cable enters the home, and the ground attached there. If this is not the household electrical ground, it should be unified with the household ground by an additional wire run to the main ground rod.

Even if all the plumbing is copper or other metal, the water meter often breaks the earth ground. Proper grounding requires a "jumper" strap to connect both sides of the water meter, and the street side should then be unified back to the household ground.

The result of all of this is that everything refers to SAME ground potential and a current, once in the ground wires, will STAY in the ground wires (IOW, no ground loops). Ground loops, while also annoying, are indicators of grounding problems. I used to do sound reinforcement for big road shows and we often had to "lift" grounds (three prong to two prong adapters are even called "ground lifters"). This was to cure ground loops between power taken from different sources in a hall or arena. Every so often, a singer would get a nasty shock when he touched a microphone - evidence that ground loops can involve some serious current.

Anyway, I applaud you all for taking this on. There are lots of self-appointed experts that claim grounding is irrelevant. Nothing could be further from the truth.

#6 OFFLINE   harsh

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Posted 10 May 2007 - 04:42 PM

I'm dubious about Option 2 versus NEC.

#7 OFFLINE   Milominderbinder2

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Posted 11 May 2007 - 08:06 AM

I'm dubious about Option 2 versus NEC.

Thank you to everyone for your posts here and PM's to me. I continue to make refinements based on your input.

I added this verbiage:

While the dish manuals show Option 2, the NEC never recommends daisy-chaining grounds. Also in Option 1, you should not combine ground taps on the cold water pipe.

Also, what if that cold water external pipe is PVC below grade? In some parts of the country that is typicaly now.

In my first darft I did not include the Option 2 diagram. In the end I fet it was safer to just use the exact materials from the manuals.

- Craig

#8 OFFLINE   alan

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Posted 12 May 2007 - 11:30 PM

We had five coax cables installed toward the top part of our house for use with a dish. When the DirecTV guy came to install the dish, he used the four leads for the dish and then he attached the fifth coax cable to the ground on the dish.

The five coax cables lead into the basement where the multiswitch is. The installer then took the fifth coax cable (the other end is attached to the ground at the dish) and ran a wire from it to the ground on the electrical service breaker box.

I don't think the ground is installed correctly, but the DirecTV guy said that it was.

The biggest problem that I see is that if the dish does get hit by lightening, then it seems like he has just routed a wire into the house that a bolt of lightening would follow instead of leaving this circuit path outside.

Am I just a worry wort or does anyone else think that this is wired wrong too?

Ironwood did my installation too.

#9 OFFLINE   hdtvfan0001

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Posted 13 May 2007 - 06:37 AM

My Dish is buried over 4' in the ground with concrete - the ultimate ground. My Ground Block is grounded outside via heavy gauge wire to a water pipe. All my rack-mounted electronics have a UPS and $1 Million guaranteed power strip on dedicated power line with ground plugs on all. My HD projector has its own dedicated power line with surge-protected ground plugs.

If I was any more grounded, I'd be living in a subterranean cave. Enough about grounding already. :D :lol:
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DirecTV Customer Since 1996

#10 OFFLINE   denvermtnguy

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Posted 23 May 2007 - 12:10 PM

My installer placed a grounding block before the lnb leads entered my Zinwell 6x8 multi-switch. Second installer said unnecessary with Zinwell & will detract from signal quality significantly. Still other info suggests block would be AFTER Zinwell before leads enter home.

What is actual best practice, code, DTV guidelines, etc.?

If you have no ground source, how deep a rod, etc.

Thanks!

#11 OFFLINE   harsh

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Posted 23 May 2007 - 12:13 PM

What is actual best practice, code, DTV guidelines, etc.?

Best practice is covered in the first post. Grounding the multiswitch is not required nor does it substitute for a grounding block.

#12 OFFLINE   harsh

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Posted 23 May 2007 - 12:18 PM

My Dish is buried over 4' in the ground with concrete - the ultimate ground.

Concrete is an effective insulator. Grounding rods must be conductive and they must all be connected by heavy wire. From there, each device must have its own run of wire directly to a "bonding point".

#13 OFFLINE   denvermtnguy

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Posted 24 May 2007 - 08:16 AM

Best practice is covered in the first post. Grounding the multiswitch is not required nor does it substitute for a grounding block.



Harsh, sorry, to bother you or others, but since first post diagram doesn't show a multi-switch in its diagram, I'm still unclear.

Grounding block after multiswitch (8 lines my case)as cable enters house, or grounding block before multiswitch (4 lines from dish)?

Thanks!

#14 OFFLINE   gblues

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Posted 31 May 2007 - 10:09 AM

Out of curiosity, is there any simple way to test to make sure the dish is grounded? I'd rather not find out the hard way...




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