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The section 250 code passages, excerpted and furnished by Todd Humphrey, become easier to read and interpret if one inserts spaces between subsections, and adds interlinear analysis:

250.53 Grounding Electrode System Installation...
(D) Metal Underground Water Pipe.
Where used as a grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(l) and (D)(2)...
.
(2) Supplemental Electrode Required. A metal under-ground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(7). Where the supplemental electrode is a rod, pipe, or plate type, it shall comply with 250.56. The supplemental electrode shall be permitted to be bonded to the grounding electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure.
Exception: The supplemental electrode shall be permitted to be bonded to the interior metal water piping at any convenient point as covered in 250.52(A)(1), Exception.

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(Note: the exception alluded to here is that a Supplemental Electrode can be connected to the water pipe further than five feet from where it enters the building, provided the building is commercial, is professionally maintained, most of the water pipe is exposed, etc., etc.)

Continuing...

250.53 Grounding Electrode System Installation...(contination)...

(G) Rod and Pipe Electrodes.
The electrode shall be installed such that at least 2.44 m (8 ft) of length is in contact with the soil....

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So section 250.53 appears, to me, to govern the installation of something called the Grounding Electrode System, which I believe to be the safety ground responsible for the bonding of the entire Class A electrical system to earth, and satisfying the conductivity resistance and reliability requirements of that section can involve using Supplemental Grounding Electrodes, such as a rod that is at least eight feet long. But the grounding requirements for "equipment", surely including low voltage communications electronics devices, begins here:

250.54 Supplementary Grounding Electrodes.
Supplementary grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.11 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as the sole equipment grounding conductor....

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Notice, first, that 250.54 is defining Supplementary Grounding Electrodes, whereas 250.53 defines Supplemental Electrodes. Supplemental Ground Electrodes complete the development of the Ground Electrode System, whereas Supplementary Ground electrodes facilitate the grounding of attached equipment.

Supplementary Grounding Electrodes do not have to meet the more robust current capacity sufficiency standards of Sections 250.50 and 250.53(C) that Supplemental Grounding Electrodes must meet, and, in the Communications electronics sections, it specifies that their bonding requirement can be met by #6 copper wire. They also do not have to meet the resistance requirement of Section 256. There is no minimum rod length given for such Supplementary Grounding Electrodes mandated in 254.54, and so the five foot rod that has been referenced in cited posts by electricians Jim Parker and Larry Fine is not inconsistent with anything I read in the limited excerpts of NEC 250 that have been posted in this thread. Now, whether this five-foot rod length referenced in Section 800 is applicable to satellite or terrestrial antenna mast grounding, antenna downlead grounding, or cable TV entrance wiring would depend on the actual wording of and interpretation of the current language of sections 810 and 820.

You make a couple critical errors.

Section 800 does not apply to TV antennas or satellite dishes as you state. It does not apply to any form of antenna distribution system. Any part of 800 cannot be used to argue that 5 foot ground rods are allowed for satellite, cable, or MATV.

Article 800 applies to Telephone, telegraph (except radio), outside wiring for Fire Alarm and burglar alarm, and similar central station systems: telephone systems not connected to central station systems but using similar types of equipment. methods of installation and maintenance.

Like I said before NO ONE should trust what is said in these forums. You have fallen victim to that very thing.

There is a revision to the 2002 NEC, 800.40A4 (communication cable) and 820.40A4 (Community Antenna TV), that states that the ground wire for communication circuits entering 1 and 2 family dwellings be less than 20 feet. If the building grounding system is more than 20' away, a ground rod shall be driven, and that rod shall also be bonded to the building ground with a #6 wire. The rod must be at least 5'x1/2".

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That text in red does NOT appear in the 2002 NEC. As stated Article 800 does not apply to satellite or cable TV, so any part of that is meaningless. Article 820.40(A)(4) says this.

(4) Length.
The grounding conductor shall be as short as practicable. In one- and two-family dwellings, the grounding conductor shall be as short as practicable, not to exceed 6.0 in (20 ft) in length.

Exception: In one- and two-family dwellings where it is not practicable to achieve an overall maximum grounding conductor length of 6.0 m (20 ft), a separate ground as specified in 250.52(A)(5), (6), or (7) shall be used, the grounding conductor shall be grounded to the separate ground in accordance with 250. 70, and the separate ground bonded to the power grounding electrode system in accordance with 820.40(D).

(D) Bonding of Electrodes. A bonding jumper not smaller than 6 AWG copper or equivalent shall be connected between the community antenna television system' s grounding electrode and the power grounding electrode system at the building or structure served where separate electrodes are used.

Added to the 2005 code
FPN: Similar grounding conductor length limitations applied at apartment buildings and commercial buildings will help to reduce voltages that may be developed between the building's power and communications systems during lightning events.


Your whole part on supplemental grounding does not apply to satellite, cable or MATV. The NEC says when a metal water pipe is used as a grounding electrode it shall be supplemented with ground rod. NEC 2002 Article 250.53(D)
This article has no bearing on satellite.

The NEC is very simple to understand. The problem starts when people do not actually READ the NEC and trust what others say. Another problem is the attempt to apply parts of the NEC that do not apply.

If you read nothing else please read the next section. It will make you think, I promise.

Here are the basic truths about satellite and antenna grounding.
To meet the NEC requirements, you must ground your mast and coax in accordance to 810. The coax must also comply with 820 (810.3), but that does not remove the requirements to meet 810, it only adds additional codes, not provide in 810.

This is were most people miss the boat. 820 is used for the installation methods and types of coax cable ie.. fire rating. The grounding section of 820 (820 section 3) is almost word for word the same as 810. The only major difference is the size of the grounding conductor. 820 says 14 awg, whereas 810 says 10 awg copper, 8 awg aluminum or 17 awg CCS. This is were things get a little interesting.
If you ground the mast using 17 awg CCS, you can ground the coax using 14 awg copper. Or can you? As long as you can argue that 14 awg copper has lower resistance than 17 awg CCS, you should have no problem. Remember, you must meet both 810 and 820. 810 does not mentioned the use 14 awg. It only mentions 10 awg copper, 8 awg aluminum, and 17 awg CCS. Since 17 awg CSS has more resistance than 14 awg, you cannot use that for the coax since it fails to meet the 820 requriement of 14 awg. Since 810 does not say you can use 14 awg, that only leaves 10 awg. However, if your local authoriteis agree that 14 awg copper exceeds the properties of 17 awg CCS (who would not agree) , you can use 14 awg copper, and meet NEC. You may not meet other requirements, but you will meet NEC

So why then do we use 10 awg???

Because every installer has been trained to connect the mast ground to the ground block and then use 10 awg to ground the ground block. This practice is not technically allowed under the NEC. The mast ground and the coax ground are required to be grounded to the same proper grounding points. When you ground the mast to the ground block, you are not grounding to an ground point allowed for under the NEC. You are in effet piggy-backing two grounding wires to one

I have no idea who first started grounding the mast to the ground block, but it has caught on. The concept is simple. A 10 awg copper can handle the grounding requirements of both the 17 awg CCS and the 14 awg coax ground. The ground block combines the two grounds into one. This is a logical adaption of the NEC. While not to the letter of the code, it does meet the spirit of the code. This is why I so strongly believe that installers MUST understand the code. When they are faced with a situation where you cannot meet the codes requirements, only with an understanding of the code can you hope to find an alternative means, that still provides a safe installation.

I would like to thank AntAltMike for a pleasant conversation. To me this is what forums do best. Provide a means for professionals to discuss issues.

One thing I left out. I stated that you could use 14 awg to ground the coax, so long as you grounded the mast separately using 17 awg CCS. That is ONLY true if your local authorities agree. Please check.

There is another problem. It is very hard to get 17 awg wire to bond to a 6 awg or larger ground conductor. You should also use separate split bolts (or whatever you use) to bond the mast and coax ground. Those damn things are not cheap. It actually becomes cheaper in most cases to ground the mast to the ground block and use 10 awg.

To really mess you all up, I will leave you with this thought. How many coax cables can be grounded with a single ground wire? The code does not address issue. I have been told that EVERY coax providing service TO a building must be grounded. Not every coax entering a building, just those providing service to the building. CATV only has one coax servicing the building, but satellite can have four or more coax cables providing service to the building. I am not suggesting that you must install a 10 awg for each coax from the dish.

But ask yourself this. Why do four coax cable ground blocks have four lugs to install a ground wire? Why do three coax cable ground blocks have three lugs. You only need one lug for the mast ground and one for the ground wire.

Could it be that to be UL approved, the manufacture must provide one ground wire attachment point for every coax providing service, because according to UL you really need to separately ground EVERY coax from a dish? That would be the most strict interpretation of the NEC.

Think about it. Logic dictates that at some point as you increase the number of cables servicing a structure, a single 14 awg ground wire would fail to provide aduquent protection. At some point you need to provide separate grounding means. Could it be that it has already been determined to be ONE servicing coax per ground conductor? How else can you explain that for every coax grounded via a ground block, there is a separate ground lug on that block?

Todd Humphrey said:

One thing I left out. I stated that you could use 14 awg to ground the coax, so long as you grounded the mast separately using 17 awg CCS. That is ONLY true if your local authorities agree. Please check.

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More precisely, we were never explicitly prohibited from using 14 gauge wire, but the 1999 revision said that whatever was used also had to be approximately equal in current carrying capacity to the outer conductor of the coax, and all electrical inspectors I have talked to are of the opinion that at the high frequencies of a lightning strike, where the electrons travel on the outside of the conductor, that its current carrying capacity is determined almost entirely by its outer diameter, and they would not allow 14 gauge to be used in that application. The cable companies in New Hampshire and Massachusetts used 12 gauge solid insulated to ground the coax outer conductors, but one inspector required me to use 6 gauge. He said that even though 6 gauge was probably not equal in current carrying capability, he could not justify requiring anything larger because the code allowed the ground rod bonding jumper to be 6 gauge, so no purpose would be served by using something larger when the 6 gauge bonding jumper would still be the weakest link in the ground path.

There is another problem. It is very hard to get 17 awg wire to bond to a 6 awg or larger ground conductor.

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I take small, strong needle-nose pliers and bend tiny zig-zags into the 17 gauge wire before I even attempt to join it to a larger wire in a clamp.

You should also use separate split bolts (or whatever you use) to bond the mast and coax ground. Those damn things are not cheap. It actually becomes cheaper in most cases to ground the mast to the ground block and use 10 awg.

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Two installations parts whose prices defy reason: One is split bolts. The other is the 1/8" and 3/16" guy wire clamp U-bolts. If you go into the wrong hardware store, the tiny U-bolt clamps cost over $3 each, but I can buy them in bulk for $.22 each.

If they now allow stranded ground wire for the outer coax conductor, which your 2002 and 2005 section 820 abstraction suggests, then at least it is now possible to buy conforming ground wire in a home supply/hardware store. They always stock 10 gauge stranded insulated, both green and black, but they never stock 10 gauge solid insulated. I always have to buy that from an electrical wholesaler, at a price that is anything but wholesale.

To really mess you all up, I will leave you with this thought. How many coax cables can be grounded with a single ground wire? The code does not address issue. I have been told that EVERY coax providing service TO a building must be grounded. Not every coax entering a building, just providing service to the building. CATV only has one coax servicing the building, but satellite can have four or more coax cables providing service to the building. I am not suggesting that you must install a 10 awg for each coax from the dish.

But ask yourself this. Why do four coax cable ground blocks have four lugs to install a ground wire? Why do three coax cable ground blocks have three lugs. You only need one lug for the mast ground and one for the ground wire.

Could it be that to be UL approved, the manufacture must provide one ground wire attachment point for every coax providing service, because according to UL you really need to ground EVERY coax from a dish? That would be the most strict interpretation of the NEC.

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I've never seen a three or four coax ground block. Do we even call them Siamese blocks, or has perhaps some contemporary science fiction character been honored?

Until DBS came along, the hole in most single coax ground blocks wasn't even big enough to accommodate 6 gauge wire. They had to be reamed out, which meant that we were voiding the UL listing by making them more suitable.

One electrician claimed that if RG-6 coaxes have the approximate current carrying capacity of 6 gauge solid copper, then four of them in parallel have the current carrying capacity of 2 gauge copper.

I think that the four lugs are provided, not for a one-coax/one ground wire relationship, but because, realistically, no installer is going to carry any ground wire larger than he thinks is adequate for the grounding of a single coax. It is plausible that the UL will only approve a ground block that has the capacity to reliably connect enough ground wire cross-section as the likely coax outer conductors will need to be grounded in conformity with NEC 820. But even then, if you used RG-11 quad...

I think that the four lugs are provided, not for a one-coax/one ground wire relationship, but because, realistically, no installer is going to carry any ground wire larger than he thinks is adequate for the grounding of a single coax.

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The key part to your comment is ".....carry any ground wire larger than he thinks is adequate... "

The installer should not have to think, just follow the code. Nice thought in an ideal world. However, if the NEC requires one 10 awg ground wire per coax, they do not come out and say it, but then you have that whole equal in currant carrying capacity comment. But since COAX is not rated on its currant carrying ability, there is no cut and dry decision that anyone can make. I will admit that this part of the NEC is not clear. Or maybe it is, and coax cable manufacturers are not doing their job by providing the specs we need?