Jump to content


Welcome to DBSTalk


Sign In 

Create Account
Welcome to DBSTalk, like most online communities you must register to view or post in our community, but don't worry this is a simple free process that requires minimal information for you to signup. Be a part of DBSTalk by signing in or creating an account.
  • Start new topics and reply to others
  • Subscribe to topics and forums to get email updates
  • Get your own profile page and make new friends
  • Send personal messages to other members.
 
Guest Message by DevFuse

Photo
- - - - -

Dish far from house ground


  • Please log in to reply
68 replies to this topic

#61 OFFLINE   P Smith

P Smith

    Mr. FixAnything

  • Registered
  • 19,330 posts
  • LocationBay Area
Joined: Jul 25, 2002

Posted 26 October 2012 - 11:41 AM

New install ? Everything will be installed by a tech. If you will think he did grounding wrong, do not sign his work order.

...Ads Help To Support This SIte...

#62 OFFLINE   westom

westom

    Mentor

  • Registered
  • 44 posts
Joined: Aug 08, 2009

Posted 26 October 2012 - 09:34 PM

a. the 1 gauge wire from the dish to ground is not a ground source, it is intended to bleed off static discharge built up in the antenna (LNB). ...

Point of ingress of the lightning to the satellite system, a ethernet port from the internet provider to our monitoring system, his system was grounded as well.

If a ground is for static discharge, then a 36 gauge (hair thin) wire would be sufficient. Why is that a 1 gauge wire? Nobody installs a more than quarter inch thick (maybe 80 amp) wire to discharge static. Protection already inside each LNB makes static discharges irrelevant. That 1 gauge wire is for even earthing a direct lightning strike.

If an ethernet port was damaged, then that is most likely an outgoing path; not the incoming path. Damage on that outgoing path means some other incoming path must exist. If a coax between two buldings was not properly earthed at both buildings, then a lightning strike to one building was a direct strike, incoming on the coax, and outgoing (destructively) to earth via ethernet. Damage is on the outgoing path; not incoming path.

If an interconnection is not earthed at both buildings, then a lightning strike to one building can be a direct strike incoming to electronics inside the other building. Which electronics are damaged? Which electronics have an outgoing path to earth?

Earthing appliances does not provide transistor protection. Protection is about earthing a surge current. Not about earthing appliances. Earthing the appliance may simply make that appliance a better and destructive connection to earth.

Many electricians understand ground as only defined by code. Grounding for surges involves requirements not defined by code. Code addresses human safety. Code does not define transistor safety. Transistor safety requires earthing that exceeds what is required by code. To earth before a surge current gets anywhere near to appliances.

Apparently coax was not earthed; violated those earthing requirements. Worse, lightning currents were apparently permitted inside that other building. Therefore earthing was also defective over there.

#63 OFFLINE   Neurorad

Neurorad

    Cool Member

  • Topic Starter
  • Registered
  • 21 posts
Joined: Nov 22, 2009

Posted 06 November 2012 - 02:36 PM

Just some followup, and closure...

Installer had no issue using the 8 awg bare copper that I installed from the ODU location to the cold water bond, in the MBa below.

Dish is mounted on the back of the house, not visible from the street; success.

Install took about 3 hours total, no real problems. In preparation, I ran RG6 from the attic/ODU location to the wiring closet, and added the 8 AWG bare copper.
Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense. -Buddha

#64 OFFLINE   AntAltMike

AntAltMike

    Hall Of Fame

  • Registered
  • 2,632 posts
  • LocationCollege Park MD (just outside Wash, DC)
Joined: Nov 20, 2004

Posted 06 November 2012 - 08:27 PM

Lightning impacted(direct strike) adjacent building (140 ft away)

Spent 3 days reinstalling our system, all electronics dead, most of coax scorched on center conductor, roughly 60 DTV set top boxes would not power up.

Point of ingress of the lightning to the satellite system, a ethernet port from the internet provider to our monitoring system, his system was grounded as well.

Satellite Company Insurance claim of 37000
Property insurance claim of 250000+


Moral of the tale, No matter the intention of the installer, mother nature will find a weak point and exploit it.


I was part of the crew that installed five 4.5 meter Patriot Dishes and 9 Blonder Tongue cut to channel antennas on National Captioning Institutes roof in 1994. We grounded the hell out of everything, but some other contractor installed a small, Ku dish and its lnb polarity switching cable was the path for the lightning damage, and as far as I know, the NEC no longer requires rotor lines to be grounded. Grounding the rotor cables used to be required, back when they were flat and it required BOTH outer conductors to be grounded.

#65 OFFLINE   AntAltMike

AntAltMike

    Hall Of Fame

  • Registered
  • 2,632 posts
  • LocationCollege Park MD (just outside Wash, DC)
Joined: Nov 20, 2004

Posted 06 November 2012 - 08:34 PM

If a ground is for static discharge, then a 36 gauge (hair thin) wire would be sufficient.


I've long assumed that the reason that mast grounding mandated 8 gauge aluminum, 10 gauge copper or 17 gauge copper clad steel was based on physical ruggedness to best assure that the wire would withstand physical stress over the years.

Why is that a 1 gauge wire?


most likely, Dan succumbed to finger fatigue.

#66 OFFLINE   n3ntj

n3ntj

    Hall Of Fame

  • Registered
  • 5,678 posts
Joined: Dec 18, 2006

Posted 07 November 2012 - 08:45 AM

I've spent a lot of time reading about 'proper' satellite dish grounding. The NEC seems to be pretty specific, but not specific enough.

I'm planning a new install, replacing Comcast cable. I've spent a lot of time running cables in my house, for LAN and distributed audio, and I've done my best to stay 'within code'.

I could do this install myself, but I don't have the time. I really want to get it done.

It seems most subcontracted DirecTV installers try to ground 'properly,' but aren't aware of the NEC rules - it's not part of the training, and it's not clear in the installation guides.

Where I want the dish placed is far from the service entrance, and whole-house ground, at the house back corner. The installer will want to place the dish at the front of the house, near the service entrance, because that is the easiest place - and near the service entrance.

I've researched grounding fairly extensively. This graphic gem from Mike Holt helps (link fixed):

www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/GroundingSatelliteDishandLead-InCables~20020303.htm

Bottom line - what wire/cable can I run from the dish to the service entrance for grounding?

Looks like a 17 AWG copper clad steel messenger wire would suffice, for both mast and coax, according to the NEC guidelines and Mike Holt. Can people confirm? I've read of the need for a 10 AWG copper wire, for coax grounding.

(Water main is buried outside and behind drywall inside, not an option.)

Thanks so much.


If the dish is on the opposite side of the home from your electrical service grounding system, then a separate ground rod in the proximity of the dish (within 6 meters) would be required by the NEC. Then, both ground rods (dish and electrical service) are required to be bonded to each other using at least #6 copper to prevent a possible voltage difference between the two.

The grounding terminal clamp can not be used for another conductor.. each conductor gets its own grounding terminal clamp, although new construction also requires a shared grounding system with phone, cable, satellite, etc. The terminal strip where the coax from the dish is connected (somewhere near the dish) must also be bonded to the dish's ground rod as well. In my travels I find that most satellite dishes are NOT properly grounded or bonded per NEC requirements and most D* installers I talk to have no idea what grounding, bonding, or NEC even mean.
HD Snob - "Friends Don't Let Friends Watch Cable".
Electrical/RF Engineer & Inspector
DirecTV Equipment: HR24-200, HR24-100, 5LNB Slimline, AM21, SWiM 8 installed (MRV)
HR-2x Configuration: Native OFF. Units OFF when not in use.
TVs: 2 Panasonic Plasma TV's each using HDMI (one 1080p/one 720p)
DirecTV customer since 1998. Plus HD DVR package w/ NHL Center Ice & MLB Extra Innings.
OTA Antenna: Homebrew UHF & VHF antennas w/ 30dB amplifier fed w/ RG-6 Quad-shield coax.

#67 OFFLINE   Neurorad

Neurorad

    Cool Member

  • Topic Starter
  • Registered
  • 21 posts
Joined: Nov 22, 2009

Posted 08 November 2012 - 07:59 AM

If the dish is on the opposite side of the home from your electrical service grounding system, then a separate ground rod in the proximity of the dish (within 6 meters) would be required by the NEC. Then, both ground rods (dish and electrical service) are required to be bonded to each other using at least #6 copper to prevent a possible voltage difference between the two.

Agreed. This is true for ALL cables entering a house (phone, cable, mains, pet fence, landscape lighting), to diminish damage from nearby surges. As the small, wall mount dish does not convey surges from nearby strikes, I'm not too concerned about 'proper' grounding of it. The dish and mast SHOULD be grounded in some form, to reduce static discharge buildup - though it's usually an issue for larger dishes.

The grounding terminal clamp can not be used for another conductor.. each conductor gets its own grounding terminal clamp, although new construction also requires a shared grounding system with phone, cable, satellite, etc. The terminal strip where the coax from the dish is connected (somewhere near the dish) must also be bonded to the dish's ground rod as well. In my travels I find that most satellite dishes are NOT properly grounded or bonded per NEC requirements and most D* installers I talk to have no idea what grounding, bonding, or NEC even mean.

Agreed. 2008 NEC guidelines for new construction mandate the use of an Intersystem Bonding Termination (IBT), a 'common' ground block, for communications systems, grounding conductors, and bonding conductors.

"The IBT provides a single, easily identifiable, physical termination device to which bonding (grounding) conductors of all other systems are to be connected. No struggle to locate an acceptable bonding location. No need for additional listed hardware to facilitate the connection. The installer simply connects the protection device's bonding (grounding) conductor to the IBT terminal and … DONE!"

http://www.ashirepor...er-Systems/1953

It will make satellite dish installations easier.

If I wanted my dish installation to meet code, in my preferred location, at the rear of the house, it would have required a series of grounding rods, I believe 20 feet apart, strung together with 6 AWG copper, connecting the ODU/ADU to the service entrance ground. I think it would have to be buried 24 inches below grade, but not certain.
Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense. -Buddha

#68 OFFLINE   n3ntj

n3ntj

    Hall Of Fame

  • Registered
  • 5,678 posts
Joined: Dec 18, 2006

Posted 08 November 2012 - 02:26 PM

Yes to the above, except that a satellite dish MUST also to shed static charge that can accumulate simply from wind blowing across it. That is why the dish itself also needs to be properly grounded (as noted in NEC chapters 810 and 820).
HD Snob - "Friends Don't Let Friends Watch Cable".
Electrical/RF Engineer & Inspector
DirecTV Equipment: HR24-200, HR24-100, 5LNB Slimline, AM21, SWiM 8 installed (MRV)
HR-2x Configuration: Native OFF. Units OFF when not in use.
TVs: 2 Panasonic Plasma TV's each using HDMI (one 1080p/one 720p)
DirecTV customer since 1998. Plus HD DVR package w/ NHL Center Ice & MLB Extra Innings.
OTA Antenna: Homebrew UHF & VHF antennas w/ 30dB amplifier fed w/ RG-6 Quad-shield coax.

#69 OFFLINE   Neurorad

Neurorad

    Cool Member

  • Topic Starter
  • Registered
  • 21 posts
Joined: Nov 22, 2009

Posted 09 November 2012 - 09:38 AM

The dish and mast SHOULD be grounded in some form, to reduce static discharge buildup - though it's usually an issue for larger dishes.


Yes to the above, except that a satellite dish MUST also to shed static charge that can accumulate simply from wind blowing across it. That is why the dish itself also needs to be properly grounded (as noted in NEC chapters 810 and 820).


Yes, I did mention that. ;)
Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense. -Buddha




spam firewall