grounding satelite and antenna on roof

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  #1  
Old 01-26-07, 05:10 PM
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grounding satelite and antenna on roof

I have a satelite dish on my roof as well as an attenna. Both of them are not grounded. They have blocks by the each enterance but no ground, approx 15ft apart. They are both however on the opposite side of the house from the electrical panel. I was gonna run a ground and just install a new ground rod but looking online and researching it says even if I do that I still have to run a ground wire from the new ground rod to the electrical panel ground rod What I was wondering can I run the one ground from the satelite grounding block to the attenna grounding block and then from the antenna grounding block run it either under the siding or about a few inches under the ground around the house to the grounding rod? or do I have to run one wire approx 50ft from the satelite ground block directly to the electrical grounding rod and then another whole wire from the antenna ground block to the electrical grounding rod. Also is it safe to run that long of a path under ground? any advise is appreciated
 
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Old 01-26-07, 06:27 PM
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http://www.dslreports.com/faq/2626
 
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Old 01-26-07, 07:43 PM
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A ground rod for equipment such as this is known as a "supplementary electrode", as opposed to a "supplemental electrode" required in the NEC. This type of electrode does not have to be bonded to the electrical service or system.

http://enews.prismb2b.com/enews/electricalzone/codewatch/2006_12_26_december_26_2006/display
 
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Old 01-27-07, 04:59 AM
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Ok but assuming I dont ground it, I would then assume that I have the risk of damaging my equipment in the event of a surge or lighting strike? I am gonna go ahead and ground it. I looked at the link and it says if I run another ground rod I still need to connect that to the original grounding rod. If I do that can I just run the wire under the ground or under the siding to the other grounding rod. It would have to run along the back of the house and wrap around to the side?
 
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Old 01-27-07, 06:42 AM
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Pete,
Look at 810-21.

Brian,
You need at least a no. 10 wire. The code also says that it must be protected from physical damage.

If you use a metal raceway, both of ends of the raceway need to be bonded to the ground wire with a listed device. (they make a special ground clamp for this)

IMHO if the wire is strapped just below the siding it would not need protection from physical harm, but I am not the inspector in your area.

Quote from the 2005 NEC:
================================

810.21 Grounding Conductors Receiving Stations. Grounding conductors shall comply with 810.21(A) through 810.21(K).

(A) Material. The grounding conductor shall be of copper, aluminum, copper-clad steel, bronze, or similar corrosion-resistant material. Aluminum or copper-clad aluminum grounding conductors shall not be used where in direct contact with masonry or the earth or where subject to corrosive conditions. Where used outside, aluminum or copper-clad aluminum shall not be installed within 450 mm (18 in.) of the earth.

(B) Insulation. Insulation on grounding conductors shall not be required.

(C) Supports. The grounding conductors shall be securely fastened in place and shall be permitted to be directly attached to the surface wired over without the use of insulating supports.

Exception: Where proper support cannot be provided, the size of the grounding conductors shall be increased proportionately.

(D) Mechanical Protection. The grounding conductor shall be protected where exposed to physical damage, or the size of the grounding conductors shall be increased proportionately to compensate for the lack of protection. Where the grounding conductor is run in a metal raceway, both ends of the raceway shall be bonded to the grounding conductor or to the same terminal or electrode to which the grounding conductor is connected.

(E) Run in Straight Line. The grounding conductor for an antenna mast or antenna discharge unit shall be run in as straight a line as practicable from the mast or discharge unit to the grounding electrode.

(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
(2) If the building or structure served has no grounding means, as described in 810.21(F)(1), to any one of the individual electrodes described in 250.52; or
(3) If the building or structure served has no grounding means, as described in 810.21(F)(1) or (F)(2), to an effectively grounded metal structure or to any of the individual electrodes described in 250.52

(G) Inside or Outside Building. The grounding conductor shall be permitted to be run either inside or outside the building.

(H) Size. The grounding conductor shall not be smaller than 10 AWG copper, 8 AWG aluminum, or 17 AWG copper-clad steel or bronze.

(I) Common Ground. A single grounding conductor shall be permitted for both protective and operating purposes.

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

(K) Electrode Connection. Connections to grounding electrodes shall comply with 250.70.
=====================================
 
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Old 01-27-07, 07:00 AM
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Thumbs up

I never knew that requirement existed for reception devices.
This is usually done by the Sat guys so I do not go to that section of code much.
Besides, there is not must Satellite done around here anymore.

Thanks for the heads up Jeff!
 
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Old 01-27-07, 07:09 AM
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Good info. This is for ALL dishes/(I understood antennas).

I thought the dish guys would grab that. Now that I look around I don't see too many grounds on those dishes.

Could be a nice opertunity here.
 
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Old 01-27-07, 08:36 AM
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Thanks for the great info back.
I read that I can's put it in the ground, what about running it inside the house directly to the circuit breaker box and connecting it to the ground there?
 
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Old 01-27-07, 08:38 AM
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I've read that unless all the grounds are bonded together there's a risk of receiver damage from lightening strike. A strike could occur at one end of the house or the other. The distance between the antenna ground and the main house ground causes an electrical potential that makes current flow through the antenna coax. If all the grounds are bonded together then the bonding wire carries the current instead of the coax cable.

The risk would seem higher when the dish or antenna is located on a pole or post separate from the house. Apparently the further apart the antenna and the house are, the more likely a ground strike will create different current values at the two locations. The article I read said if the grounds cannot be bonded, it's better to not ground the antenna at all. This reduces the chance a ground strike will create current flow through the ground, to the antenna, the coax, then the receiver. Made sense to me so, on my previous Dish receiver, I removed the ground wire from the post where the dish is mounted away from the house. It would appear though that, if you have a high antenna mast, it may be more likely to draw a direct strike instead of the ground. In that case I would ground it, bonded or not.

FYI, my latest dish upgrade to HD is a lease deal with DishNetwork, I don't own the equipment, and it was installed by a company/contract installer. I left the antenna ground just as they put it, even thought it's not bonded to the house ground. If a ground strike zaps the receiver, they can't blame me for the failure.

I would be interested in some other opinions on this configuration.
 
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Old 01-27-07, 09:13 AM
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two questions...One, what does it mean by bonded? and two what is a metal raceway? I read about having it grounded but if it is not bonded then it is useless. Isnt grounding it the same as bonding it?
 
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Old 01-27-07, 09:17 AM
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Grounded means connected to earth, somewhere. It can mean very different things actually. Connecting to a ground rod is a vastly different thing than connecting to the ground bar in the main panel.

Bonded means creating electrical and mechanical continuity. So by connecting two ground rods together with a #6cu wire you are bonding the rods.

Metallic raceway is any form of metal conduit. Such as pipe, Wiremold, etc.
Nonmetallic would be plastic or PVC.
 
  #12  
Old 01-27-07, 11:38 AM
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This is what I plan on doing tell me if this sounds ok, I am gonna run the ground from the antenna dish down to the grounding block for the direct tv which is the furthest away. Then I am gonna run the ground from the antenna mast directly down to the ground block for the antenna. I am then gonna a ground wire from the direct tv grounding block (the furthest away) to the antenna grounding block. Then I will run a wire from the antenna block inside the house running it along the floor joist directly to the water pipes enterance and ground it there. Does this sound ok?
 
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