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#85168 - 06/02/03 07:12 PM grounding a dish
installer ken Offline
Junior Member
Registered: 06/02/03
Posts: 1
Loc: leavenworth ks USA
The NEC requires a lighting rod be grounded by a grounded with a grounding rod not bonded to house system.
Dish network requires there metal dish(lighting rod)be grouded as well. the problem is there want it grounded to the house system. I know this is wrong but can not get them to read the NEC code book correctly. The dish its are and mast are all metal the LNB is incased in plastic and is connected to the dish by a five inch plastic Y bracket. I have told them this gives the separation so that the proper NEC codes can be followed. My biggest problem is that they want the dish grounded but want us to use the messager wire attached to are cable. Now this wire is only about 20 gage so there proper ground is far from proper. So how can I get dish who wants a proper ground follow NEC codes
_________________________
Kenneth A Hlastead
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#85169 - 06/02/03 07:22 PM Re: grounding a dish
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
Ken,
The lightning protection grounding electrode system is required to be bonded to the electrical system grounding electrde. 810.21 requires that the dish be connected to the electrical grounding system. The minimum size of the bonding conductor from the dish to the electrical system ground is #10. If you install a ground rode for the dish, then 810.21(J) will require that you install a #6 from the dish ground rod to the electrical grounding electrode system.
Don
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Don(resqcapt19)
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#85170 - 06/07/03 07:37 AM Re: grounding a dish
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Ken,
Save yourself some grief and drive a seperate stake for the Dish grounding system.
You can also get in-line surge arrestors for coaxial cable,the only trick is fitting the required connectors to the cable, these will help if your LNB is struck.
But it's best to keep all Lightning currents outside of the house, out there, they will not cause too much damage!.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#85171 - 06/07/03 07:47 AM Re: grounding a dish
George Corron Offline
Member
Registered: 05/16/01
Posts: 717
Loc: Lorton, Va USA
Ken,
As a young mechanic (that was NOT last year ) I used to help my brother in law who owns his own radio business when things were slow. That oughta be a hint, when's the last time things were slow, and back then, people would shut down jobs in a rough winter cause production would drop so bad....... but I digress.

One of his customers had him install a dish. This customer lived on an old strip job, a place where they knocked down a mountain for the coal, and what used to be straight up is now a 40 acre flat level surface, frankly a beautiful place, but prone to lightning.

Like all radio installers, he ignored/did not understand the ground system. He had been struck by lightning 3 times when I got there.

All was grounded like normal, two rods at the house, simple coax and control to dish... I said normal, not legal.

Using his equipment (ya don't buy a 40 acre flat mountain top in coal country bagging groceries for a living) I trenched in a ground ring around the house, pulled in a #6 from the dish, drove a rod at the dish, and put suppressors on service, well pump, and dish. Viola, no more problems.

This is an extreme example, he was the tallest thing for 3 counties, but he never had problems with lightning damage again.

Hee hee, also taught some people some things about cad welds, LONG before they were code legal. BTW, of course, Don has the code correct, so I need not bother requoting.
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#85172 - 06/07/03 08:45 AM Re: grounding a dish
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Trumpy,

Quote:
Save yourself some grief and drive a seperate stake for the Dish grounding system.


This would be in addition to the connection to the buildings grounding electrode system required by 810.21(J) right?
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#85173 - 06/21/03 06:24 AM Re: grounding a dish
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Bob,
You know that I come from New Zealand.
If it was my house, I'd go for both!.
I was talking to a friend of mine that is in Holland, recently, and his nieghbour had a Dish that had a direct Strike.
It knocked out the supply(mains) to the building, all of the telecoms circuits for a week, and everyone in the building that had a computer with a Modem, had the darned things cooked!.
Nasty things them lightning strikes!.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#85174 - 06/21/03 05:34 PM Re: grounding a dish
Ron Offline
Member
Registered: 03/13/02
Posts: 582
Loc: White Plains, NY
Even if a separate rod was driven, it is required that it be connected to the remainder of the building's grounding electrode system.
_________________________
Ron
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#85175 - 06/22/03 12:20 AM Re: grounding a dish
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Ron,
That law seems a wee bit strange, for the currents that lightning strikes have, wouldn't it be best to keep the two systems segregated?.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#85176 - 06/22/03 04:39 AM Re: grounding a dish
RickG Offline
Member
Registered: 07/04/01
Posts: 37
Loc: South County, R.I. USA
Trumpy
Here in the states the NEC requires that all grounding electrode systems be bonded together. If they were seperate, it would be like having 2 nails in a grapefruit (or a kiwi (are kiwis citric?) ), there could be a voltage (potential) across the 2 nails (electrodes). In the event of a lightning strike or power line surge, all systems that are bonded together (electrode systems, pipes, ducts, etc ) will rise & fall together, so there is little or no difference in potential between systems. The latest issue of NEC Digest had a short article on bonding & why we size bond conductors relative to the service entrance conductor size. I need to reread the story, so I will take it on my vacation/ cruise next week!
Rick
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#85177 - 06/22/03 01:29 PM Re: grounding a dish
dougwells Offline


Member
Registered: 05/03/03
Posts: 1137
Loc: kamloops BC Canada
Comscope RG6 5731 has a 17awg copper clad steel grounding conductor this is not the messenger type cable this cable says on it that this is a ground conductor and it also says on it that it is nec compliant this has troubled me fog sometime and have called comscope and they emailed me back saying this cable can be used as commucation cable for satellite installations i use a 6awg ground block and bond the 17awg and 6awg with the supplied bolt on the grond block and then bond the 6awg to the service equipment ground.the purpose of this is for electrical faults and static discharge . for lightning I suggest a surge protector with insurance because you will need to replace the connected equipment when lighting strikes your dish
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