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Proper Grounding and Video Hum

2708 Views 29 Replies 10 Participants Last post by  gremmy, 
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I have three questions that will appear related but which I do not believe really are, after conducting plenty of testing on my own.

Question #1) My DishNet technician tells me that his company's practice is to NOT GROUND the new HD Dishes in houses with 3 pronged outlets. He says that the dish is grounded through the home's electrical system, via the coax connection on the DVR unit. This sounds like a lot of garbage to me, since it basically means that the build-up of static eletricity would be discharged down the coax and through my equipment. Is this guy telling the truth or smoking much dope?

Question #2) My HDMI port on the 622 is generating a 60hz style video hum, very similar to a ground loop. But since the system isn't grounded (and since the hum remains even if I disconnect all of the incoming coax from the box), I really don't think the problem is a traditional ground loop. My question is this: Does anyone have any guesses as to what could be causing my video hum on the HDMI port? Could it be a defective DVR box?

Question #3) I am seeing a strobing effect (pulsating brightness changes) on a few stations, including ShowTimeHD. I see this on my 622 and on the non-DVR box hooked up to my other HDTV. Is this signal related or hardware related?
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boylehome
I'm no expert but the 622 needs the three prong ground and it need to be plugged into a properly grounded A/C outlet. The unit needs grounded so it can properly operate. You may not notice a problem immediately but eventually, you will start seeing bizarre behavior. The dish system also needs to be grounded in accordance with code.

Showtime HD has a pulsating picture (brightness change). I have seen this for months and wonder why they don't fix it.
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boylehome said:
I'm no expert but the 622 needs the three prong ground and it need to be plugged into a properly grounded A/C outlet.
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No problem there. My unit is plugged into a 3 pronged outlet.

My question is not about the box, but about the dish itself. My tech tells me that they no longer GROUND the DISH in houses like mine (with 3 pronged outlets) because the 3 pronged outlet takes care of grounding the Dish. This makes absolutely no sense to me whatseover. He tells me they changed their SOP regarding DishNet installations a while ago. He went on to say that DirectTV still requires the grounding block, but that Dish changed their hardware so that a grounding block was not required. This smells very fishy to me. I'm afraid I'm going to wake up to a bunch of very expensive electronic toast during the next big thunderstorm.

Showtime HD has a pulsating picture. I have seen this for months and wonder why they don't fix it.
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Interesting. The problem must be with Dish, since I just switched from Charter and ShowHD was rock solid with no pulsating. Has anyone told Dish about this?
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boylehome
gremmy said:
No problem there. My unit is plugged into a 3 pronged outlet.

My question is not about the box, but about the dish itself. My tech tells me that they no longer GROUND the DISH in houses like mine (with 3 pronged outlets) because the 3 pronged outlet takes care of grounding the Dish. This makes absolutely no sense to me whatseover.

Interesting. The problem must be with Dish, since I just switched from Charter and ShowHD was rock solid with no pulsating. Has anyone told Dish about this?
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Gremmy, BTW welcome to the forum. I think that your assumptions about the 60hz hum are good. From my exposure to this and other forums and reading grounding procedures, as listed in the user guide, I don't have a clue as to why your installer would not ground the dish before where the cable enters the structure. Maybe they changed some laws? I doubt it though.
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boylehome said:
Gremmy, BTW welcome to the forum. I think that your assumptions about the 60hz hum is good. From my exposure to this and other forums and reading grounding procedures, as listed in the user guide, I don't have a clue as to why your installer would not ground the dish before where the cable enters the structure. Maybe they changed some laws? I doubt it though.
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Since the Dish isn't grounded, I'm guessing that the hum is a defective component or some other sort of interference. I was hoping someone could let me know if any other 622 users have experienced video hum unrelated to a ground loop.

As far as the dish not needing to be grounded, I too am confused by what the installer told me.
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C
My installer told me the Dish had to be grounded. No hummmm here.
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D
I'been through this explanation too many times so pardon if I do it one more time in summary- no details...

There are 3 types of grounds we deal here. Static grounds, powerline grounds, and electronic circuit grounds. The first two are regulated by code. Any professional installation that violates local codes as well as national electrical codes is not only illegal but also at risk of severe liability. The mounting of your antennas of which a DISH is in this category MUST be properly grounded according to the code. No details here as I said "in summary" In addition, the coax must also be properly grounded as defined in the code as it enters the building according to the code. Reason- static grounding for reduction of static electricity buildup to reduce the liklihood of lightning strike as well as small static discharge that can destroy tiny electrical components in your electronics.

Power line grounding. Must follow the code. Your 120VAC outlet with ground must be properly polarized. You can check this out with a simple 3 neon light tester costing less than a couple bucks at Home Depot. If the hot and neutral is reversed, hazardous shock can occur in some devices. If the ground is not connected, the ground path in most electronics will trace back through the neutral (white wire) but this can result in unstable operation, a.k.a. hum!

Electrical circuit grounds. These are internal and most of us need not worry about them. They can be at power ground potential or not, depends on the circuit. IT is wrong to bond a circuit ground to power ground as it may destroy the component.

Back to power grounds- Power grounds- Green wire, is bonded to the neutral wire White, at the breaker box. Additional bonding downstream of the breaker box is not generally hazardous but may, in some cases cause a ground loop float to occur which also can cause audio hum in some amps. In a stereo system, all grounding for the power should be done at one point for a given circuit.

If you have an issue with an installer who wants to violate the local codes on grounding, I'd report him to your local building inspector, and to the DBS company that hired him.

Now about the claim that video has hum- I guess this is a misnomer because by definition there is no sound of hum that would eminate from a picture device. But any audio hum may accompany a distortion artifact in the picture as black bars heavy or thin. If I saw this show up on a DVI cable or any video cable, I'd be hunting down a powerline open ground or, a hot / neutral reversal in a receptacle somewhere. get a detector and test all outlets for proper polarity.

"hum" bars on a CRT screen may also be caused by two monitors or any high frequency oscillator in close proximity which is actually a beat frequency artifact. Shielding of the oscillators and ferrite chokes in I/O lines may be indicated. Remember, computers are also oscillators.
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DonLandis said:
If you have an issue with an installer who wants to violate the local codes on grounding, I'd report him to your local building inspector, and to the DBS company that hired him.
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Would you agree that this guy is blowing smoke when he claims that the "static ground" is handled via the "power ground" on the DVR box?

Sounds to me like he's full of it.

EDIT: I double checked, and I only get the HUM if the DVR is plugged in. I was mistaken when I stated otherwise. Although the problem does go away when the HDMI cable is unhooked from the DVR, the problem exists only when the DVR has power, which makes sense. Disconnecting the COAX cables from the DVR has absolutely no impact whatsoever.

Also, when the DVR is plugged into a different outlet via an extension cord, the problem almost completely vanishes. This leads me back to thinking I've got a ground loop in the electrical system, but there are only two ground wires coming out of the one and only breaker box in my house. Per code, one of these goes to the main cold water inlet pipe and the other one goes to the main house ground stake outside.
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Would you agree that this guy is blowing smoke when he claims that the "static ground" is handled via the "power ground" on the DVR box?

Humorous answer- I don't know about the installer blowing smoke but in a good E-storm your DVR sure might if all you rely on is the power line ground for static electricity drain off your dish.
The installer is just lazy and probably ignorant of the technical aspects of his job.

Per your detective work- I would get one of those detectors and check the wiring polarity and the integrity of the gound. If you have a volt meter, check the voltage between the gound and the white side It should be close to zero volts. Then check the ohms between the two receptacles' grounds. It should be close to zero ohms. Somewhere you have a broken connection on the grounds or a poilarity switch. Not info yet to determine if you have a ground loop issue but you are doing good detective work so far.
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DonLandis said:
Would you agree that this guy is blowing smoke when he claims that the "static ground" is handled via the "power ground" on the DVR box?

Humorous answer- I don't know about the installer blowing smoke but in a good E-storm your DVR sure might if all you rely on is the power line ground for static electricity drain off your dish.
The installer is just lazy and probably ignorant of the technical aspects of his job.

Per your detective work- I would get one of those detectors and check the wiring polarity and the integrity of the gound. If you have a volt meter, check the voltage between the gound and the white side It should be close to zero volts. Then check the ohms between the two receptacles' grounds. It should be close to zero ohms. Somewhere you have a broken connection on the grounds or a poilarity switch. Not info yet to determine if you have a ground loop issue but you are doing good detective work so far.
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I'm going to install a grounding block post-haste. Is this something I can do myself or do I need to call Colonel Klink? Is there a Web Page out there that has instructions for how to install the grounding block?

And here's another problem I've got. I think that properly grounding the coax is going to be very difficult because the dish is mounted on my roof, about 100 feet away from the main grounding rod for the house. To properly ground the dish, I'd need to run an extra 100 feet of wire to get the block close to the main ground, and then another 100 feet of wire to get the coax back to the opposite side of my basement where the DVR is. In short, the technician wasn't really paying attention, and he mounted the dish in the worst possible location.

And if Just bond the wire from the grounding block to a random cold water pipe near the DVR, don't I run the risk of introducing a ground loop to the system?
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Just in case anyone is still bothering to read this thread, I thought I would ask whether anyone thought I would be okay if I ground the incoming coax to a cold water pipe on the far end of the house from the main cold water supply?

Per code, my breaker box has two ground wires. One goes to the main entry for cold water supply, one goes outside to the main house grounding stake. An electrician I spoke to said that it's possible that the main pipe supplying water to my house (the pipe buried under the earth) could be made of PVC (despite the fact that the line coming into the house is copper), and therefore I might not get an adequate ground by bonding to the cold water pipe.

Is it likely that my 9 year old home would have passed the electrical inspection if one of its required ground lines was connected to a copper supply water pipe that was in turn attached to PVC on the outside of the house?

And my other question -- am I going to end up with a ground loop if I bond the coax to the cold water pipe and not the stake outside?

The reason I'm asking these questions is that bonding the coax to the actual grounding rod outside the house is going to be a royal PITA beause of the location of the dish and the DVR. Because of the insane cable lengths required, I'll probably have to move the dish, which means I'll probably have to repair my roof. So if I can just bond to the cold water pipe, that would be much, much easier.
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Amherst
The basic answer is yes, you may bond to the cold water pipe but you must carefully inspect the pipe back to the panel ground connection making sure you have a solid copper run.
You may also opt to run a solid bare ground wire (buried is better) back to the outside ground rod install a second grounding acorn to connect to rod. This instead of changing RG-6 runs.
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gremmy- You will not generate ground loops with static ground installation unless your house wiring is faulty! If you do, you seriously need to inspect and correct your house wiring.
I would recommend you install a separate 8' to 10' ground rod driven into the ground close to the point where your Dish / antenna coax enters the house. Radio Shack or Home Depot has these and often can recommend the right length for your geographical area. Use the appropriate coax ground block and run a solid wire from this block to the ground rod. Do not worry about tapping into the same ground point as your house panel box uses. In addition, you should have the dish mount structure connected to a ground rod, same or separate as the coax ground. You can use a heavier guage wire for this purpose. I use 12 Ga solid wire for the dishes and OTA antenna mounts and 16 ga solid for the coax entry point using as short a path as practical.

A note about grounding to a water pipe: I have an older house that had galvanized water pipe throughout the house and out to the city main. The house wiring was done by a licensed electrician who properly used the water pipe according to code for the panel box ground. Years later the home owners had the water supply pipe replaced with plastic! Well there went the ground. But the plumber, not being an electrician did not concern himself with this. OK, so I move in and discover this and all sorts of other wiring deficiencies in the house. The only ground point I had for the house was the service primary at the meter box outside. I had about 15 VAC floating on the ground in the house wiring. I drove an 8' ground rod into the ground below the panel box and ran a 12 Ga solid wire to this rod from the panel box. 15 volts floating was gone!

One more thing- In the interest of accuracy for the physicists and electrical engineers- Earlier, I stated there were 3 types of grounds for this discussion. Actually there is a fourth but in this discussion it plays a very very minor role if at all. That would be an RF ground. At the frequencies TV operates at, it is essentially a non-concern but at short wave and AM transmission frequencies, RF ground integrity is directly related to signal efficiency. Ham radio and Broadcast stations need be concerned here but DBS and OTA TV reception, no. Reason: At these frequencies, the static grounds are quite adequate for RF grounding purposes. :)
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Amherst
DonLandis said:
gremmy- You will not generate ground loops with static ground installation unless your house wiring is faulty! If you do, you seriously need to inspect and correct your house wiring.
I would recommend you install a separate 8' to 10' ground rod driven into the ground close to the point where your Dish / antenna coax enters the house. Radio Shack or Home Depot has these and often can recommend the right length for your geographical area. Use the appropriate coax ground block and run a solid wire from this block to the ground rod. Do not worry about tapping into the same ground point as your house panel box uses. In addition, you should have the dish mount structure connected to a ground rod, same or separate as the coax ground. You can use a heavier guage wire for this purpose. I use 12 Ga solid wire for the dishes and OTA antenna mounts and 16 ga solid for the coax entry point using as short a path as practical.

A note about grounding to a water pipe: I have an older house that had galvanized water pipe throughout the house and out to the city main. The house wiring was done by a licensed electrician who properly used the water pipe according to code for the panel box ground. Years later the home owners had the water supply pipe replaced with plastic! Well there went the ground. But the plumber, not being an electrician did not concern himself with this. OK, so I move in and discover this and all sorts of other wiring deficiencies in the house. The only ground point I had for the house was the service primary at the meter box outside. I had about 15 VAC floating on the ground in the house wiring. I drove an 8' ground rod into the ground below the panel box and ran a 12 Ga solid wire to this rod from the panel box. 15 volts floating was gone :)
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Don the use of 12ga. and 16ga grounding wire is strictly prohibited by NEC rules, for mechanical and electrical reasons both. Do not use smaller than 8 ga. solid for any grounding. The only exception is branch circuit grounding with overcurrent protection on the circuit. A smaller wire risks being burned off under fault. It is also easily broken and therefore against the NEC rules.
Aside from that, your diagnosis of the electrical system sounds dead on.
In my many years experience in commercial and industrial electrical installation I have found it best to not cheap out and create separate grounding systems that do not tie into the original system it can in many instances be unreliable due to the soil. Whether a ground rod is driven at the location or not it's best to tie into the original system. A buried bare copper ground conductor is best for this.
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gremmy said:
Just in case anyone is still bothering to read this thread, I thought I would ask whether anyone thought I would be okay if I ground the incoming coax to a cold water pipe on the far end of the house from the main cold water supply?

Per code, my breaker box has two ground wires. One goes to the main entry for cold water supply, one goes outside to the main house grounding stake. An electrician I spoke to said that it's possible that the main pipe supplying water to my house (the pipe buried under the earth) could be made of PVC (despite the fact that the line coming into the house is copper), and therefore I might not get an adequate ground by bonding to the cold water pipe.

Is it likely that my 9 year old home would have passed the electrical inspection if one of its required ground lines was connected to a copper supply water pipe that was in turn attached to PVC on the outside of the house?

And my other question -- am I going to end up with a ground loop if I bond the coax to the cold water pipe and not the stake outside?

The reason I'm asking these questions is that bonding the coax to the actual grounding rod outside the house is going to be a royal PITA beause of the location of the dish and the DVR. Because of the insane cable lengths required, I'll probably have to move the dish, which means I'll probably have to repair my roof. So if I can just bond to the cold water pipe, that would be much, much easier.
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I would like to explain my understanding of the current grounding requirements. The ground rod driven into the ground is the primary ground. The plumbing system is bonded to this primary ground as a safety precaution. If the plumbing were to become energized somehow you wouldn't end up with a plumbing pipe with a line voltage on it. In other words the plumbing ground is not intended to be a secondary ground, therefore it doesn't matter if the main water feed is PVC or not. It has to be this way because the electrical inspector generally has no say in how the plumbing is done.(unless the plumber tries to run a pipe through an electrical supply box :) )
Hope this helps and I'm sure others can correct my understanding or expand on it.

FWIW when I built my house in 1988 the water supply was required to enter the house via at least 5 feet of metal pipe. This requirement was for mechanical stability. In my case after that 5 feet I ran 200 feet of PVC to my well. On the well end I didn't run a 5' metal pipe from the well to the PVC. As a result the settling of the soil pulled the pipe down and cracked it at the well after about 3 years time.
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Amherst
Incorrect. NEC requires two grounds, in your case a second ground rod should have been driven and a separate conductor to the panel. The metal water pipes must always be grounded and the pvc outside disallows the water main as one of the two service grounds. Should also, by newer codes, have a jumper between the hot and cold pipes at the water heater. The electrical inspector is required to know the outside piping situation, and probably knew about the pvc from plans, not much of an inspector if he missed these basics.
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Amherst said:
Don the use of 12ga. and 16ga grounding wire is strictly prohibited by NEC rules, for mechanical and electrical reasons both. Do not use smaller than 8 ga. solid for any grounding. The only exception is branch circuit grounding with overcurrent protection on the circuit. A smaller wire risks being burned off under fault. It is also easily broken and therefore against the NEC rules.
Aside from that, your diagnosis of the electrical system sounds dead on.
In my many years experience in commercial and industrial electrical installation I have found it best to not cheap out and create separate grounding systems that do not tie into the original system it can in many instances be unreliable due to the soil. Whether a ground rod is driven at the location or not it's best to tie into the original system. A buried bare copper ground conductor is best for this.
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You are indeed correct on the 8 Ga. , but the use of 8 Ga on a coax block ??? I'd have to check you on that. It won't even fit through the hole! :) 14 Ga is what I believe will fit but as I had 9 coax blocks in a row, and located just above the ground rod by less than 10 inches of wire length. 16 ga was used. On my masts, and dish mounts I'm using standard aluminum Ground wire and I do believe it was 8 Ga. But you are correct on the main panel box ground, I should replace the new 12 Ga ground rod wire with 8 Ga for the inspector. Now that I recall when I did the kitchen he saw that and never flagged me for it. BTW- the original 1978 wiring done by a licensed electrician was 16 Ga. to the water pipe. I have since replaced nearly all the old 12 -2 w G that was older 16Ga Ground with present day standard wiring.
Also, pse note we are in N. Florida here with ground water of high Iron conductivity at 8 Ft. Makes for excellent static grounds but red staining sprinkling. All people have to do is use it and lighting damage becomes nil in a T-Storm.
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Amherst
Don if you upgrade the ground conductor to your service panel, #8 ga. is the minimum for any service and grounding conductor. Correctly sizing the grounding conductor is based according to the size of the service entrance conductors (Feeds).The NEC has tables for this if you need to look at the table pm me. Please be extremely careful when working on energized service grounds, as many precautions need be taken for personnel and attached equip/appliances, you may cause a floating neutral and burn things up. Best if you can shut her down to work on.
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DonLandis said:
Electrical circuit grounds. These are
If you have an issue with an installer who wants to violate the local codes on grounding, I'd report him to your local building inspector, and to the DBS company that hired him.
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I had the guy come back out and ground the coax to a cold water pipe. He said that his install-company is telling all of their installers *not* to ground the coax from these dishes because "DishNet changed their hardware and this is no longer required." He said, "You wouldn't believe how many 100s of these dishes I've installed with no coax ground."

Seems to me like they are playing with fire -- perhaps literally.

I'd be hunting down a powerline open ground or, a hot / neutral reversal in a receptacle somewhere. get a detector and test all outlets for proper polarity.
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Ugh, this is driving me crazy. Here are the tests I've done so far.

1) Bought an 8-dollar outlet tester at Home Depot
2) Plugged it into all of my new outlets. They all indicated "two yellow lights," which means that there are no reversals and everything is wired correctly.
3) I found an "open hot" on an outlet in the kitchen. But if I bump the tester a bit, the "two yellow lights" come on. This outlet has a tendency not to work. This outlet is nowhere near where I'm seeing the problem, but is it possible that this open hot is causing the problem I'm seeing?
4) I swapped one 622 DVR out for the identical non-DVR version of the box in the other room. Same problem.
5) I noticed that while watching an HD DVD, if I unplug the 622, all sorts of whacky electonic flickering interference scatters across the screen. This does not happen when I unplug any other component -- just the DVR.
6) I also notice that my 60hz hum does *not* show up while watching DVDs via HDMI -- only HD DVDs, perhaps because I'm using analog cables for HD DVD? I really have no idea. It's totally bizarre.
7) I've tested the cables. It's not the cables as far as I can tell.
8) I also had the Satellite guy move the incoming coax away from a high voltage line, which he had previously had it mounted within an inch of. That did *not* fix this particular problem.

Now what? Back to HD for a voltage meter?
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gintzj
Any dish on your roof needs to be grounded : for hum and most for Lightining if it hits the dish the system is grounded
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