Grounding....

kb7sei · 02-14-2007, 09:41 AM

I know it's been talked about on here before, but the search doesn't seem to pull it up for me.

I have some dish mounts I want to put on the roof that allow the cables to run through the roof in a watertight manner. They work like the drain vents the plumbers install on the roof. I like this idea as I won't have cables running around my nice new home.

The problem I'm seeing here is for ground connections. Obviously, there isn't a suitable ground point on the roof. However, I could run a wire up from the basement when I pull the RG6 and use that for grounding. It would be connected to the electrical box to get a ground point. I was thinking 12AWG or maybe that aluminum grounding wire they have at Home Depot should do it. I would ground the dish itself and use ground blocks in the mount or attic to ground the coax.

Also, is there a place I can get direction and such for the various DTV sats? I know where the main one is, I'm interested in the new HD sats. I want to make sure I position the mount with a nice clear view while hopefully hiding the dish in the back of the house for WAF.

I was going to pull 5 RG6 and a ground up there. 4 for DTV and 1 for OTA HD locals. Is that enough for the new HD dishes?

John T Smith · 02-14-2007, 10:09 AM

Dish pointer page
http://www.directv.com/DTVAPP/customer/dishPointer.jsp

goony · 02-14-2007, 11:14 AM

Better forum for satellite install/setup issues: http://www.dbstalk.com

IIRC, #12 copper may be too small for satellite grounding.

Do a title-only search for grounding in the above forum for a wealth of topics.

kb7sei · 02-14-2007, 02:06 PM

Quote:

Originally Posted by John T Smith

Dish pointer page
http://www.directv.com/DTVAPP/customer/dishPointer.jsp

Thanks, but that one only covers single-sat dishes. I want to know how to point an AT9.

kb7sei · 02-14-2007, 02:50 PM

Quote:

Originally Posted by goony

Better forum for satellite install/setup issues: http://www.dbstalk.com

IIRC, #12 copper may be too small for satellite grounding.

Do a title-only search for grounding in the above forum for a wealth of topics.

Thanks for the pointer, a lot of reading material there. Looks like there is no one size fits all sort of answer. I did see that experiments show a #8 can withstand at least some lightning, interesting. I guess I'm considering an "odd" install as I haven't seen anyone discuss this option. I'll keep searching I guess.

samo · 02-14-2007, 03:20 PM

What you need is a dual RG-6 with messenger wire. You will have 6 lines (always nice to have a spare) and will only need to pull 3 cables. Messenger wire is sufficient for Dish grounding. Note, YOU DON'T WANT your ground wire to be large gage to withstand "some lightning". If your Dish gets hit by lightning you WANT your ground wire to melt as quick as possible to prevent your house from catching fire. Ground wire on satellite dish has one purpose only - to remove build up of static electricity. Most convenient way of running ground wire is to use dual (or single) RG-6 with messenger.

rminsk · 02-14-2007, 04:58 PM

Quote:

Originally Posted by samo

Note, YOU DON'T WANT your ground wire to be large gage to withstand "some lightning". If your Dish gets hit by lightning you WANT your ground wire to melt as quick as possible to prevent your house from catching fire. Ground wire on satellite dish has one purpose only - to remove build up of static electricity. Most convenient way of running ground wire is to use dual (or single) RG-6 with messenger.

This is for electrical code and it is for lighting protection and is not only static build up . You must use the proper gauge the local/national code specifies. The last time I checked the National Electrical Code you needed nothing smaller than 10 AWG copper, 8 AWG aluminum, or 17 AWG copperclad steel or bronze from the grounding block to the electrical ground.

See http://www.mikeholt.com/mojonewsarch...s~20020303.htm

IminMs · 02-14-2007, 05:37 PM

http://satcalculator.freehostia.com/

http://www.solidsignal.com/satellite...all_videos.asp

http://emantechnology.com/lookangle.asp

http://www.satelliteguys.us/showthread.php?t=65610

These should help with any sat. your looking for.

greywolf · 02-14-2007, 06:55 PM

Quote:

Originally Posted by rminsk

This is for electrical code and it is for lighting protection and is not only static build up . You must use the proper gauge the local/national code specifies. The last time I checked the National Electrical Code you needed nothing smaller than 10 AWG copper, 8 AWG aluminum, or 17 AWG copperclad steel or bronze from the grounding block to the electrical ground.

See http://www.mikeholt.com/mojonewsarch...s~20020303.htm

Bleeding off static buildup is the method used for lightning protection. A static discharge into the atmosphere can be a precursor to a lightning strike. Notice how 17ga steel/bronze seems the odd choice out of the group for conductivity. None of the group is expected to save the building if a dish is struck by lightning by conducting the energy to ground. They are just there to conduct small static charges to ground which just about any wire could do. The specification is about physical strength. A broken wire will allow static charge buildup to attract lightning.

rminsk · 02-14-2007, 07:20 PM

Quote:

Originally Posted by greywolf

Bleeding off static buildup is the method used for lightning protection. A static discharge into the atmosphere can be a precursor to a lightning strike. Notice how 17ga steel/bronze seems the odd choice out of the group for conductivity. None of the group is expected to save the building if a dish is struck by lightning by conducting the energy to ground. They are just there to conduct small static charges to ground which just about any wire could do. The specification is about physical strength. A broken wire will allow static charge buildup to attract lightning.

The grounding line is also used for other voltage transients and contact with higher voltage systems which are not static buildup. I agree you will get a differental before a lightning strike but a grounding systems are not only for static buildup. A lightning bolt by definition is a dischare of static electricity. The OP was stating it was not used for lightning protection which it definitely is. Nothing is going to withstand a direct lightning hit. Lightning protection systems are designed to blow in a controllable manner.

greywolf · 02-15-2007, 08:04 AM

I left off that grounding the dish effectively puts the charge state of that dish equal to the charge state under the surface of the ground. This makes the dish less attractive to lightning than surfaces around it. Protection from transients, nearby lightning strikes and physical damage is provided by single point (effective) grounding including grounding of the coax near where it enters the building, the dish, and the electrical panel to the same ground rod or, in some cases, underground copper water supply pipe. In cases of separate electrical ground rod and A/V equipment ground rod, it's vital to bond the two rods with 6ga copper to effectively retain single point grounding.