Antenna and Satellite Gound on Multi Unit building

[Rjrus]

We have an 8-plex multi res. building. There is the electrical breaker panel for each of the units in the upstair mechanical room. We want to provide for grounding of an outside satellite dish in that room. It is my understanding that grounding to the electrical breaker box enclosure in that room with bare 10 awg copper or 17 awg copper clad steel would be the proper way to ground the dish and bond the coax. It was suggested that the proper grounding must be hooked up to the ground wire where electrical enters the building. This is over 150 ft from the dish and would require transversing other units.

rjrus

 

[celtic]

[The Dish on Successful Satellite Installations]

[Article 810: Radio and Television Equipment]

(Both links from the current issue of EC&M ~ 2/1/2007)

 

[Rjrus]

No answer here

No answer here

Celtic, no concrete answers in these articles. Seems that no one wants to answer this. Do you have a professional NEC code opinion on the specifics of my question or not?

Sincerely

 

[tom baker]

As the submitter of a code change to Art 810 in the 2002 NEC regarding antenna grounding, section 810.21 has the requirements. In 810.21F is a laundry list of the acceptable bondwire grounding locations
(F) Electrode. The grounding conductor shall be connected as follows:
(1) To the nearest accessible location on the following:
a. The building or structure grounding electrode system as covered in 250.50
b. The grounded interior metal water piping systems, within 1.52 m (5 ft) from its point of entrance to the building, as covered in 250.52
c. The power service accessible means external to the building, as covered in 250.94
d. The metallic power service raceway
e. The service equipment enclosure, or
f. The grounding electrode conductor or the grounding electrode conductor metal enclosures; or
When you run coax, the rules for coax are in Art 820 and contain similar grounding requirements

Its very important to create for the antenna and coax a single point ground, by running a bond wire to the electrical grounding system, at one point.

If you bond to the electrical breaker room, in a lighting strike, there will be a difference of potential between the antenna, coax, and electrical ground, resulting in current flow, resulting in damage to electronic equipment.

For your distance you may need to increase the size of the bonding jumper.
I bond my antennas with 2 AWG just for physical protection.

 

[Rjrus]

Still no clear answer here

Still no clear answer here

With electrical service hitting the building at one end there is no way of bonding the satellite cable in the middle unit with out exceeding the 20 ft. lenght. It is not feasible to run the coax and ground all with way were the service hits the building and back to the unit. Are the electrician required to drive a ground rod and bond to water in each of the units. If so that would be the only good ground electrode available within the unit, but I am not sure they are required to bond to the water in each of the units and many of these units are using plastic water piping. The 20 ft rule is for single and two family dwellings. What exceptions are there in this bonding delima for a multi-dwelling building such as the 8 plex.

 

[Rjrus]

Still no clear answer here

Still no clear answer here

With electrical service hitting the building at one end there is no way of bonding the satellite cable in the middle unit with out exceeding the 20 ft. lenght. It is not feasible to run the coax and ground all with way were the service hits the building and back to the unit. Are the electrician required to drive a ground rod and bond to water in each of the units. If so that would be the only good ground electrode available within the unit, but I am not sure they are required to bond to the water in each of the units and many of these units are using plastic water piping. The 20 ft rule is for single and two family dwellings. What exceptions are there in this bonding delima for a multi-dwelling building such as the 8 plex.

 

[tom baker]

There are no exceptions.
To quote Mike Holt
"Code is Code
We don't like the rules we don't agree with if they cost us time and money"
I would suggest you read over the rules in Art 810 and 820 to see how you can install to meet the requirements of the NEC.

 

[Rjrus]

Tom,

With all due respect (I'm just a junior blogger), I am not looking for an exception. I am trying to make sense of it. There is not a satellite in the country grounded properly on row housing were the electrical service hits the building at one point for all units unless the satelite installer runs the cable(s) with ground accross the neighboring units to service ground and then back to the unit. Am I seeing this right? or does the code make provisions else where for this type of construction? Does the code require the electrial service to bonded to water lines in each of the units or not?

 

[tom baker]

What the code allows is what I posted. I know thats not what you want to hear.
Did reading the rules in Art 810 and 820 help?

 

[don_resqcapt19]

Am I seeing this right? or does the code make provisions else where for this type of construction?

There are no other provisions in the NEC.

Does the code require the electrial service to bonded to water lines in each of the units or not?

Yes, metal interior water pipe sytems are required to be bonded to the electrical grounding electrode system by 250.104(A), however that is not of any help because your connection to the water pipe must be within 5' of where the water pipe enters the building.
Don

 

[Rjrus]

Does the 20ft max. distance between coax discharge unit and grounding electrode in section 810 apply to Antenna and Satellite systems coax discharge unit as well. Is this wire's minimum size 10 awg copper as stated in 820 or 14 awg as stated in 810.

 

[hbiss]

Article 810 is the applicable article for dishes and receiving antennas.

Quote from link provided by celtic:

This grounding/bonding conductor, for one- and two-family dwellings, cannot be longer than 20 feet, and should be as short as possible. Any bends should be gradual and kept to a minimum. If the distance is greater than 20 feet, drive a ground rod in close proximity. Attach the conductor to the ground rod with a ground rod clamp listed for direct burial, and drive the ground rod below grade. Using a second ground rod clamp, attach another conductor — this time 6 AWG bare or insulated, solid, or stranded copper — and tie into the building's ground electrode system.

There is no requirement in Article 810 that the grounding/bonding conductor cannot be longer than 20 feet. That paragraph is extremely good advice though and can actually help you. If you drive a ground rod below the dish location and connect it to the dish with a minimum #10 copper (that also picks up the ground block where the coax enters the building) you now have several options in getting the #6 bond wire back to the service ground. It can be direct buried, run on the foundation or inside the building. Remember that this can pick up other ground rods along the way that are for dishes on the other units.

In a nutshell this is a step-by-step on what you must do.

-Hal