Grounding of a satellite dish mast

[todd humphrey]

Hello,

This topic could go in the low voltage section, but since it is about grounding, I will put it here.
My name is Todd Humphrey, I have been installing satellite systems for 22 years. Currently I own and operate DBS Install, a support business for satellite dealers and technicians. I am also a retail council member with the Satellite Broadcasting and Communication Association (SBCA) which manages the satellite TV industries installer certification program.

There are many of us in the satellite business which are questioning the need to ground a satellite dish mast. The coax grounding requirement is not in question, that we understand 100%. The question is about the mast as defined in 810.
I can fully understand the mast grounding requirement of a 10' TV antenna mast on the roof of a house, but it seems that applying the same rule to a small piece of metal attached to the side of the house is somewhat unnecessary.

Section 810 says that 17 awg copper coated steel is a suitable ground conductor for a mast ground. The confusion sets in when the coax shield has less resistance 17ohms per thou vs 9 ohms per thou.
Are we wrong is in thinking that if the coax were bonded to the mast and the coax grounded to specs at POE, then both the mast and coax would be grounded?

What reasons can the NFPA have for requiring a mast installed 6 feet above the ground on the side of your house to be grounded, when the coax is already grounded, and in many cases electrically bonded to the mast or could be with a bonding strap between the mast and the LNBF (thing the cable connects to)?

What do we do when we come to a house that has been pre-wired with the satellite cables routed to a point on the roof or eave, and there is no ground wire? Are we to say "Sorry, I can only install the system if you allow me to install a ground wire down the side of your house, but since that would exceed the 20 foot limit (820.40(4))I cannot install your satellite system."
Even if a ground wire was installed along with the coax cables, it usually is over the 20 foot length before it even comes close to a point where you could drive a rod. There are no allowances for using a larger AWG wire to offset for a longer ground conductor.

What about apartments? There is no way we can ground 99% of the apartment/condo systems we do to NEC code and yet how many dishes do you see in apartments. As the installer we are on the hook should something go wrong.

There are a whole slew of things that the satellite industry needs clarification on when it comes to grounding. It seems that the code is outdated for the reality of what we do.

I read that the NEC is taking suggestions at this time about the code. Can someone point me in the right direction on who to bring these issues up with.

Thanks

Todd Humphrey

www.dbsinstall.com
www.dbsinstallsupport.com
www.basicinstall.com

[ September 17, 2003, 03:42 AM: Message edited by: todd humphrey ]

 

[don_resqcapt19]

Re: Grounding of a satellite dish mast

Todd,
I don't think that the rule in 810.21(E) requiring the grounding conductor to be installed "in as straight a line as practicable from the mast or discharge unit to the grounding electrode" would be met if you used the coax shield to ground the mast.
Article 820 does not apply to a dish that serves a single unit. I don't find lenght requirement in Article 810.
As far as driving a rod for the dish mast, I don't see that as being permitted by 810.21(F). If you are installing a dish, the building must have electrical power. If it has electrical power, one or more of the items listed in 810.21(F)(1) must be present at the building. You can use a rod only if none of the items listed in 810.21(F)(1) exist. Note that some do not agree with my reading of this section and the very existance of 810.21(J) seems to support the idea that you are permitted to install a ground rod for the dish.
I think that you are correct that the code has not kept up with the dish industry. Your association and its members should become an active part of the NEC code making process. It is too late to propose any changes for the 2005 code. Proposals for the 2008 code will be due in November of 2005.
Don

 

[todd humphrey]

Re: Grounding of a satellite dish mast

The whole straight line issue is ignored in your industry.

Here is a typical installation that is accepted as being done properly.

The installation of a coax with an attached 17 awg copper coated steel ground wire. At the dish, the ground wire is attached to the mast. The cable and attached ground wire are routed to the contours of the house (no straight path here, unless it is a sloppy install and the cable is left drooping, that's irony)
The cable and ground are attached to a ground block which is mounted near POE. From the ground block a single #10 copper ground wire is routed to system ground.

I can only find one problem with this type of installation. My interpretation of the NEC is that there needs to be two separate ground conductors to ground and not a combining of the two (at ground block) onto the single #10. This, perhaps, is not a big deal.
A smaller issue is the fact that the ground wire is not all that straight when routed attached to the coax. Consumers would simply freak (an remove a ground)if we had to run a line drooping from the mast to ground.


As far as 820 not applying to a single family home, that is news to me. 810 which does apply to single family homes says in 810.3 that coax cables shall comply with 820. If 820 can be put a side for us, I would like to know that for sure.

The problem is so many homes are pre-wired (a lot by electricians) with the coax POE at the OPPOSITE end of the home from the ground. There is no way to meet the code and yet if we do not install, they will find someone who will and you will stop receiving work orders because you "Can't get it done"

By the book, virtually every apartment installation is not to code and yet no says anything. Until someone gets killed and then it will be the installers fault.

[ September 17, 2003, 11:09 AM: Message edited by: todd humphrey ]

 

[don_resqcapt19]

Re: Grounding of a satellite dish mast

Todd,
You're correct, I forgot about 810.3, but if 820.40 applies how can you use the #17 ground wire?. The minimum permitted size in 820.40 is #14 copper.
Running the grounding conductor in a "straight line" is only required by the Chapter 8 articles in the NEC. I don't understand the comment about the "straight line issue being ignored in your industry".
It appears that if you want to do code compliant work, you will have get the AHJs to enforce these code sections so that you and your competitors are playing by the same rules.
Don

 

[todd humphrey]

Re: Grounding of a satellite dish mast

# 17 awg is allowed for the MAST ground, not the coax ground. They are two separate ground systems.

When I say the industry is ignoring the straight line sections, I mean how can a ground wire be run in a straight line as possible when it is attached to a coax which is supposed to be installed nice and neat? You cannot.
Do you ever see homes with a ground wire routed in a straight path from mast to ground? No.

The dish is often mounted on a roof, if there is a ground wire, it is always routed next to the coax. Nice and neat. The whole straight line issue is subjective. As straight as possible to what standard? Since the customers will not accepted a straight drop to ground, we install it neatly, that is as straight as we can get. I know the customers do not make the rules, but without support from manufacturers, inspectors (they have not clue about what we do, in general) and even the industry lobby group (SBCA) we installers are left to install as best we can and take our chances that nothing goes wrong and we get blamed.

I am trying to teach young and older installers the correct way to install to reduce the chance or a law suit later. It is often hard to justify the fact that you must follow the NEC because that is the law we have, when the NEC is so out of date. Besides, I have not found ONE person who can show me a incident where property or person was damaged due to NO mast ground. Remember, we are not disputing the coax ground, only the mast ground.

To try to be the voice of correctness to an entire industry is impossible when there is no logical reason for some sections of the NEC. I can make the arguments, but I need some logical explanations for why we need to ground a 2 foot mast, when the stove pipe right next to the mast extends 10 feet into the air and is not grounded.

A few questions:

Does wind blowing across a dish build up static and there for needs to be drained to ground to avoid increased chance of lightning? I do not think so, but that is a very common thought.

If you put a metal item on your roof and then ground that item, is that not called a lightning rod? I am not sure it that is true or not and I have done a lot of research on the issue. I can find facts to support both sides of the argument However, almost every installer in our business does think it is true.

There are a lot of us who want to not only do it right, we want to improve our industry so others do it right. Currently I estimate that 90% of all satellite dish installations are not installed to code. Out of that 1/2 of the installers think they are doing in it right, but are not and the other half know they are not doing it right and do not care. Who is going know?

I have written the only nationally available installation standard for DBS installations. If you are interested.

www.basicinstall.com/dni/

Todd Humphrey

[ September 17, 2003, 12:11 PM: Message edited by: todd humphrey ]

 

[todd humphrey]

Re: Grounding of a satellite dish mast

So full of questions.

If a coax is routed through a crawl space vent, travels in the open crawl space and then travels up in to the building, is the POE the point where the coax goes through the vent or up into the wall or through the floor?

All the POE pictures I see, show the cables going through the wall. What about traveling in the crawl or attic space when the cable is not in direct contact with the framing.

Cable attachment can be an issue, I understand. Any thoughts.

 

[don_resqcapt19]

Re: Grounding of a satellite dish mast

Todd,

# 17 awg is allowed for the MAST ground, not the coax ground. They are two separate ground systems.

So you intent is to use the #17 from the mast to the coax protector and then apply the rules in 820? I think that would meet the code rules.

As straight as possible to what standard?

Maybe the rules should be more like in NFPA 780 where a minimum bending radius is specified to help prevent the lighting current from jumping off the conductor at a sharp bend.

If a coax is routed through a crawl space vent, travels in the open crawl space and then travels up in to the building, is the POE the point where the coax goes through the vent or up into the wall or through the floor?

If we apply the rules in 230.6, the coax in the crawl space is inside the building.

To try to be the voice of correctness to an entire industry is impossible when there is no logical reason for some sections of the NEC.

These are the types of issues you need to bring up in your code proposals for the 2008 NEC.
Don

 

[bennie]

Re: Grounding of a satellite dish mast

Static charges remain on above ground objects long after the source that created them has gone.
A ground electrode is not for the lightning strike, it is for clean up after the event.

The above ground objects can be both conductive and non-conductive to retain an electrostatic charge.

The feed line will attain the potential of the antenna enclosure and mast. The TV set is not grounded, therefore the electrostatic charge will appear on the chassis of the TV set. By touching components the resultant discharge can destroy the solid state devices.

An electrostatic ground conductor to an electrode, and an electrostatic antenna discharge device should be installed on a receiving dish antenna system.

This is according to the ARRL (American Radio Relay League) Antenna Manual.

[ September 17, 2003, 02:14 PM: Message edited by: bennie ]

 

[rp9ball]

Re: Grounding of a satellite dish mast

Just a note to this subject. An installer in our area recently became hung up on a 30' foot tower. The installer is alive but will be unable to work for about a year.

could this happen if the tower was properly grounded?

 

[dereckbc]

Re: Grounding of a satellite dish mast

Originally posted by rp9ball:
became hung up on a 30' foot tower.
could this happen if the tower was properly grounded?

Define "hung up" please.

 

[Guest]

Re: Grounding of a satellite dish mast

Yes and no.

 

[jay80424]

Re: Grounding of a satellite dish mast

Hi Todd, I just joined DBS install. Thanks.
I'm a custom installer in Colorado, and I have some grounding questions for all of you. I've read ALOT of posts, and it seems there is no one answer. I'm really confused. I understand the general concept, it's the application I don't get.

Here's the deal. I just wired a 6,000 squate foor, $2M house, and stuck on the grounding. I have a total of 11 lines going from a low volt box in the wall in the basement to the roof.

I can run a ground wire from the dish location, back inside the attic, through what will be finished walls, and outside to the cold water pipe to ground the dish no problem.

Q1. Is it OK that the ground line is "inside the house" ie, in the walls.

Q2. If I have multiple dishes, can they all be daisy chained onto the same ground line, or does each one need it's own line (I hope not)

Now to ground the cable.

Q3. shoud the grounding block be up by the dish, and attached to the same ground line described above, -or-

Q4. be inside the low volt pannel in the basement, with another ground wire going from the low volt pannel to another cold water pipe in the basement (there is one there that has a big ground wire going to the main 400 amp electrical service outside the house)

I hope I made myself clear, I'm quite confused.

 

[jay80424]

Re: Grounding of a satellite dish mast

One more thing, according to the Pegasus (Direct TV) website, they imply it is OK to use the coax line to ground teeh dish, but everything I seem to read says this is a violation of the NEC.
HELP!

 

[pierre]

Re: Grounding of a satellite dish mast

Hello Todd

I can see the frustration in your posts, but I can also see that you are very concerned about the proper installation as well as safety. It is quite obvious that you are very involved in your industry, and that is wonderful to see. So I say to you be a little more patient and we here will do our best to really try and help.
I think you have learned one of the first real hard lessions of the NEC, that is there is not always an easy answer. You have some very legitimate questions and it is not an area of the NEC that we all spend a whole lot of time in. If you are patient and work with us, I believe both you and the ones following this thread will both gain some valuable information.
I am going to read you posts again and try to formulate some answers, and I am sure there are others already doing the same.

Pierre

 

[pierre]

Re: Grounding of a satellite dish mast

Todd and Jay

POE - is where the cable enters the building, an exterior wall, or where it comes through the floor if from underground.
In your example of the crawl space or attic, both of those locations are 'inside' the building, so they are past the point of entrance.

Grounding of the dish is to follow 810.21.

There is no length restriction for the dish/mast grounding conductor.

This grounding conductor can be bare or insulated (my understanding of the subject would say that a bare conductor is better suited for this purpose), and run inside or outside the building (I also think keeping it outside the building would be more prudent).

As far as in run in a straight a line as practicable, that can difficult. One note to remember about the NEC 'rules', they are not written to satisfy the 'customer' but for safety reasons. They also do not say how to do it, very convienent for those who do not have to do the installation.

From the dish/mast you will run the grounding conductor to any of the locations provided in 810.21(F).

I myself have always used 10 AWG, but you are permitted to run 8 AWG Al or 17AWG copper-clad steel or bronze. I have never seen this conductor, I would not know how available it is.

810.20 Requires an Antenna Discharge Unit, a grounding block.

This grounding block should be as close to the POE as possible, and can be immediately inside the building. Again I would keep this outside if at all possible.

The lead in cables are attached to this grounding block, with the cable sheath bonded to the grounding block.
An insulated grounding conductor sized minimum 14 AWG shall be run to any location as per 820.40(B)(1)(1) - (7).
If the length of this grounding conductor is longer than 20 ft, than you will be required to connect it a ground electrode as specified in 250.52(A)(5)- (7). For all intents and purposes, a ground rod. This ground rod has to be bonded to the 'power system' electrode system with a minimum size 6 AWG conductor.

It sounds like a lot of work, and is. Once you start installing it this way, it will become a habit. I know most do not install it this way, but that is how to separate the CRAP from the GOOD. The selling point to the customer is always safety and fire, that usually sells them, and keeps you from court.
I hope this helps. Good Luck.

Pierre

 

[jay80424]

Re: Grounding of a satellite dish mast

Thanks Pierre,
So if I understand this correctly, I can run a single # 10 insulated wire from the dish, to a cold water pipe, to act as the dish/mast ground, and the coax grounding block ground, as long as it does not exceed 20 ft. I can also send this wire to the metal conduit connecting the service disconnect to the breaker pannel, or teleco box.

Can I bundle multiple dishes together on this same ground wire?

Inside the 400 amp service pannel, there is a ground wire that goes into the ground, and I believe goes down into the basement to bond the cold water pipe in there. Is it safe to connect to that?

I have heard something to the effect that you don't want to ground the satellite system to certian parts of the electrical system because it can send the current through the equipment and 400 amps is not something I want to mess around with.

 

[jay80424]

Re: Grounding of a satellite dish mast

Todd, my understanding of this,

" If you put a metal item on your roof and then ground that item, is that not called a lightning rod?"

and I am absolutely no expert of any kind,

is that it is a sort of lightning rod, however, lightning rods are designed to repel lightning, not attract it. Since they are connected to earth ground, they reduce the ground potential,and so the lightning would rather strike something else that has a higher diffrence in potential (from static electricity???).

Someone please correct me if I am wrong, or elaborate if right, I would like to understand this as well.

 

[pierre]

Re: Grounding of a satellite dish mast

Hello Jay

Yes you can run to the cold waterpipe as long as it is within 5 feet of where it enters the building.

Without enough experience, I would stay out of the electric panel, if you can get to the panel, you will see the grounding electrode conductor heading to the cold water, tap into that with a split bolt.

Connecting the dish/mast to ground/earth is not a lightning rod. But the purpose is to direct the lightning strike to the earth.

Remember lightning does not necessarily want to go to ground/earth. What happens to a plane when hit by lightning? Lightning is a static discharge that travels from one charge to an opposite charge. That is why you see cloud to cloud or cloud to tree or cloud to the roof of say a house type lightning strikes.

Pierre

 

[jay80424]

Re: Grounding of a satellite dish mast

Hi Pierre,
But dosent grounding the dish reduce the ability of the static to build up, and thus reduce the diffrence in potential? Reducing the chance of a lightning strike.

How is it that a million volts of electricity, with enough energy to arc miles through the air, isn't just going to instantly melt a 10 gauge copper wire into oblivion?

Just wondering

On the other note, There is a small solid bare copper wire comming out of the service disconnect, I can put a split bolt on that and use it as my ground. If I have 2 dishes up there, I can connect them together as well and that will suffice. The 5 foot rule on the cold water pipe is in either direction? (inside the POE)

 

[Guest]

Re: Grounding of a satellite dish mast

Originally posted by jay80424:
<snip>The 5 foot rule on the cold water pipe is in either direction? (inside the POE)

The water pipe clamp needs to be accessible. The fine points of the water pipe ground are in 250.52(A)(1)

[ September 22, 2003, 01:36 AM: Message edited by: awwt ]